(echinodermata) faunule from the early cretaceous (barremian)

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ABSTRACT—An asteroid (Echinodermata) faunule of four taxa representing three surviving families and a probable fourth is described from the Barremian ...
Journal of Paleontology, 85(6), 2011, p. 1021–1034 Copyright ’ 2011, The Paleontological Society 0022-3360/11/0085-1021$03.00

A NEW ASTEROID (ECHINODERMATA) FAUNULE FROM THE EARLY CRETACEOUS (BARREMIAN) OF MOROCCO DANIEL B. BLAKE1

AND

ROLAND REBOUL2

Department of Geology, University of Illinois, Urbana, IL 61801, USA, ,[email protected].; and 2 12, rue de la Colline, F-34360 Saint Chinian, France, ,[email protected].

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ABSTRACT—An asteroid (Echinodermata) faunule of four taxa representing three surviving families and a probable fourth is described from the Barremian (Early Cretaceous) of Morocco, northwest Africa. The four together suggest limited morphologic evolution since the Cretaceous but biogeographic and depth patterns have changed. Marocaster coronatus n. gen. n. sp. (Valvatida, Goniasteridae) combines apparent derived features of the dorsal disk and superomarginal shape with more stemward expressions of the abactinal ossicles. Betelgeusia orientalis n. sp. is a fourth Mesozoic occurrence of the Radiasteridae (Paxillosida), the new species similar to earlier occurrences from the Middle Jurassic of India, the Early Cretaceous of Texas, and the Late Cretaceous of Europe. Reported modern occurrences of the family are few, widely scattered, and limited to deeper water; the extinct species together testify to a once-broader familial distribution. Dipsacaster africanus n. sp., a member of the Astropectinidae (Paxillosida), is remarkably similar to extant congeners. Dipsacaster today is widely distributed in the Pacific Ocean but occurrences in the Atlantic are few. Because of preservation, a single small specimen of the Zoroasteridae? (Forcipulatida) cannot be identified with certainty. Extant zoroasterids are deep-water in distribution, although shallow-water Eocene representatives are known.

INTRODUCTION

are almost invariably rare, although they F are an important faunal component today in many marine settings. The history of the crown-group, which appeared and OSSIL ASTEROIDS

diversified during the early Mesozoic, is only slowly emerging with ongoing discoveries and reevaluation of existing specimens. The Triassic fossil record of asteroids is scanty, but Jurassic and Cretaceous occurrences indicate progressive emergence of the modern fauna without major change at the Cretaceous–Paleogene transition. Mesozoic asteroids are known from many parts of the world, although European representatives are the best documented. Important taxonomic treatments include the classic British studies of Wright (1863, 1866, 1880); Sladen (1891, 1893), and Spencer (1905, 1907, 1908); later papers include those of Gale (1986, 1987a, 2011). Hess (1972, 1975), augmented by shorter papers, has treated Jurassic faunas of Switzerland, and Breton (1992) focused on the Mesozoic Goniasteridae. Schulz and Weitschat (1971, 1975, 1981) treated Cretaceous asteroids of Germany, and Bru¨nnich Nielsen (1943), Rasmussen (1950), and Jagt (2000) studied Cretaceous and Cretaceous–Paleogene asterozoans from Denmark, the Netherlands, and Belgium. Beyond Europe, Blake and Reid (1998) treated middle Cretaceous asteroids from Texas, and Hess and Blake (1995), Villier et al. (2007), and the present study treat Cretaceous occurrences from north Africa. Fossils discussed here are of robust construction. More delicate asteroid species are important today in many settings but they are taphonomically vulnerable. Overall significance of fragile constructional modes through geologic time remains problematic, although some occurrences are known (e.g., Villier et al., 2004). STRATIGRAPHIC SETTING AND MATERIAL

Geologic setting.—The paleontology and geology of Morocco, North Africa, are subjects of an ongoing research program made up largely of French geologists and their Moroccan colleagues. As a part of this program, V. and R. Reboul with D. Vizcaı¨no between 2007 and 2009 collected

fossil asteroids at a site previously identified by Moroccan workers. The senior author became involved during a field trip to the Paleozoic of the Montagne Noire led by B. Lefe`bvre. The asteroid-bearing horizon is located at the western end of the High Atlas in the Tawrirt Oukanakay Region, a part of the basin of Agadir-Essaouira. During the Cretaceous, the basin formed a bay near the continental margin opening to the west toward the Atlantic Ocean. The fossil asteroids were derived from a single Barremian (Early Cretaceous) horizon and locality in the Taboulouart Formation (Witman, 1998). The locality is approximately 35 km north of the city of Agadir and 2.1 km northeast (28u) of the village of Taba. GPS coordinates of the locality have been reposited with the specimens at the Natural History Museum of Toulouse, France. The regional setting is arid and rocks are well exposed both on natural hill slopes and in numerous road cuts. The stratigraphic sequence with the asteroids consists of richly fossiliferous alternating marls and limestone beds that are not interrupted by major discontinuities. A precise biostratigraphy is based on ammonites and calpionellids (i.e., probable protozoans of uncertain affinities) as described by Ambroggi (1963), Taj-Eddine et al. (1990), Taj-Eddine (1992), Ettachfini (1991), Witman (1998), Masrour et al. (2004), and Company et al. (2008). The asteroid-rich horizon is a thin interval of buffcolored argillaceous limestone in a sequence of gray marls with many irregular echinoids. The strata vary locally in thickness; however, the asteroids were found approximately 8 m above a horizon bearing the ammonite Nicklesia pulchella d’Orbigny, 1841. The ammonite horizon in turn is about 6 m above a discontinuity at the upper surface of an oyster coquina; the Hauterivian–Barremian contact is placed at this discontinuity. The Barremian regional facies is interpreted as passing from an ammonite-rich open marine setting into a shallower-water setting. The asteroid-bearing horizon is thought to have been deposited in shallower water (not over 30 m) based on overall lithology of marls and marly limestones, oyster coquinas, and yellow calcareous sands (Moussa Masrour, Universite´ Ibn Zohr, Morocco; personal commun., 2011).

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Material.—Twenty-three more or less complete asteroids and numerous specimen fragments and scattered ossicles are available. The fossils are on bedding surfaces of nowseparated slabs of varying sizes. Some slabs bear specimens exposing both dorsal and ventral surfaces; however, stratigraphic orientations of the slabs are not available. The lithology is a buff-colored terrigenous limestone, and the bedding surfaces are silty with finely comminuted skeletal debris including fragmentary asteroids and asteroid ossicles, small ophiuroids, and echinoid fragments and spines. The cut cross-section of the largest block (that bearing specimens of Betelgeusia orientalis n. sp.) shows a finely laminated texture and suggestions of rippling and current cutting. Although the interiors of blocks are heavily indurated, the silts of the surface bedding planes are not, and some specimen breakage appears to have taken place at the outcrop. Fossils also would have been susceptible to sloughing and dissolution associated with exposure; some primary and many accessory ossicles were lost. In spite of mixed orientations of the more complete specimens, most are largely intact suggesting only limited disturbance prior to final burial. Dissociated ossicles at the tip of one of the B. orientalis specimens are little displaced, and presence of small and delicate specimens and fragments all suggest quiet periods. However, the single block with most of the Dipsacaster Alcock, 1893, specimens indicate disruption at the time of their final burial because individuals are folded and variously broken, although some spines and granules remain. ASTEROID TERMINOLOGY

Terminological usage largely follows Spencer and Wright (1966) and Blake and Hagdorn (2003). Primary ossicles are the more or less enlarged foundation ossicles of the body wall; in contrast, accessory ossicles are the spines, spinelets, granules, and pedicellariae seated on primaries. A double marginal series (inferomarginals, IM, and superomarginals, SM) arise at the unpaired terminal at the tip of the arm and serve to separate abactinal ossicles of the dorsal surface from the actinal ossicles developed between the marginals and the adambulacrals. Fascioles are channelways or grooving separating the abradial portions of many marginals. A differentiated primary circlet of abactinals is developed near the dorsal center of the disk, and in many species, a differentiated carinal series extends along the dorsal arm midline. The ambulacral and adambulacral series also arise at the terminal and extend proximally to the mouth frame. The mouth angle ossicles (MAO) form a more or less bud-like ring exposed at the center of the ventral disk surface. Distally, each MAO pair is braced by a single odontophore, and circumorals are the first ossicles of the ambulacral series beyond the MAO. BETELGEUSIA, ASTEROID PRESERVATION, AND TAXONOMIC APPROACHES

While the present paper was under review, Gale (2011) became available. Gale (2011) argued that Betelgeusia Blake and Reid, 1998, should be transferred to the Astropectinidae; here, generic assignment to the Radiasteridae is reaffirmed and comments on taxonomic concerns and approaches are included. For a number of reasons, the taxonomy of crown-group asteroids is difficult. The skeleton of small, delicate, unfused elements is almost always quickly destroyed with death. Those few fossils that survive rarely if ever show all that is desired. Both dorsal and ventral surfaces are important to interpretation, as is both internal and external anatomy. Both accessory ossicles (e.g., spines, spinelets) and primary skeletal elements

(e.g., marginals and ambulacrals) are important, yet the former, if preserved, can obscure the latter. Finally, evolution of many taxa, including some close to those discussed here, has been slow (Breton et al., 1995; Villier et al., 2007), and similar morphologic expressions can either endure or reappear; comparisons spanning significant time intervals can be misleading. Here, the writers argue three approaches offer partial escape from difficulties: 1) emphasis on apomorphies; 2) rigorous comparison beginning with computer image processing; and 3) advances in molecular phylogenetic analysis. Expression of the actinal ossicles and the actinal interbrachia provide a character complex of apomorphies supporting a monophyletic Radiasteridae sensu Blake and Reid (1998). In brief, actinals are uniform, strongly overlapping, spinose, and closely aligned in narrow, regular rows (Blake, 1987, p. 506, character 1; Blake and Reid, 1998, fig. 7.2–7.6, fig. 8.17; Blake and Jagt, 2005, pl. 3; Fig. 4.4, 4.5). Morphology is further discussed below under Systematic Paleontology In contrast, Gale (2011, p. 57, 58) did not provide apomorphies in support of his proposed transfer, but instead in comparing Cretaceous Betelgeusia with the modern astropectinid Tethyaster Sladen, 1889, this author stressed his views on marginal and also ambulacral expression; in particular, the fascioles of the inferomarginal ossicles (Figs. 3, 4) were emphasized. Comparisons without apomorphies are openended. Fascioles, for example, are not found in all astropectinids, but they are found in some of members of other families, including non-paxillosidans (e.g., Odontasteridae; Ganeriidae). Extant Luidia Forbes, 1839, and Astropecten Gray, 1840, both arguably exhibit ranges of ossicular variation greater than that between Radiaster and Betelgeusia. Comparisons across time, a concern of Hennig (1966), can miss gradational change. For example, perhaps a now-smaller taxon suffered significant extinctions while a larger diversified; the hypothesis on evolutionary ecology of Blake and Reid (1998) and below suggests disappearance of the Radiasteridae from shallow water. Quantitative approaches can help delineate ranges of variation and ultimately provide guides for the recognition of apomorphies. Blake and Portell (2009) and Blake (2010) argued that taxonomy of isolated ossicles (or select ossicles of more complete specimens) can be tested and verified or rejected based on computer imaging and statistical analysis; such approaches have been employed elsewhere (e.g., Hageman, 1991, 1995). Landmark analysis could prove as productive with asteroids as it has with trilobites (Webster, 2011) because asteroid ossicles and trilobite segments both are complex, threedimensional objects. Cluster analysis could be used to develop blind tests for the assignment of isolated ossicles to single taxa; Lane and Rowe (2009) based phylogenetic interpretation of an asteroid genus on such techniques. Based on apomorphies, the phylogeny of Blake (1987) provided a more parsimonious positioning of Betelgeusia than does that of Gale (2011, fig. 20). A monogeneric Radiasteridae emerged as the basal branch of the Paxillosida in Blake (1987, fig. 11, p. 506, character 1) based on the ventral apomorphy complex while at the same time allowing (but not requiring) fasciolate marginals to have been established in a basal paxillosidan ancestral to the Astropectinidae and the Luidiidae. Gale (2011) coded pointed tube feet in Radiaster, but the suckered disks of this genus were recognized in the original description (Perrier, 1881) and have been widely noted since (e.g., Sladen, 1889; Fisher, 1919; Mortensen, 1927; Blake, 1987, p. 506, character 2). Suckered tube feet in Radiaster are

BLAKE AND REBOUL—MOROCCAN CRETACEOUS ASTEROIDEA in accord with the phylogenetic hypothesis of Blake (1987) but discordant with conclusions of Gale (2011). Positioning of Betelgeusia and the Radiasteridae based on the above apomorphy complex not only is consistent with paxillosidan phylogeny, it also enables a hypothesis of evolutionary ecology (here and Blake and Reid, 1998) consistent with the known depth distribution of Betelgeusia. Earlier molecular results (Lafay et al., 1995; Wada et al., 1996) supported one of the key inferences of Gale (1987b, 2011), that the Paxillosida is basal among crown-group asteroids, but later, more broadly sampled and comprehensive studies embed the Paxillosida among more derived lineages (Knott and Wray, 2000; Matsubara et al., 2005; Janies et al., 2011; Mah and Foltz, 2011). There are inconsistencies, and interpretations will continue to evolve, but emerging results are broadly in accord with those of Blake (1987, 1990) and Blake and Hagdorn (2003). Molecular results are of increasing significance in many groups and can be expected to dominate morphological perspectives in the classification and interpretation of crown-group asteroids. Sequencing of the extant ultimately will help both with arrangement of extinct members of the crown-group and in the search for its Paleozoic roots. FAUNAL SIGNIFICANCE

The Goniasteridae, represented by Marocaster n. gen., and the Astropectinidae, represented by Dipsacaster africanus n. sp., are disproportionately abundant as fossils because of their relatively robust construction as well as their occurrences in the more commonly preserved shelf settings on unconsolidated substrates. Nevertheless, overall relative abundance of the two families in the fossil record seems likely to reflect ongoing importance extending back at least as far as the Middle Jurassic (e.g., Hess, 1972). The fossils described here document both similarities and differences between the Barremian and modern faunas. All four represent surviving families, and their appearances are similar to those of extant familial representatives. Significance of Marocaster coronatus n. gen. n. sp.—The Early Cretaceous occurrence of Marocaster (Goniasteridae) is well after the Jurassic earliest-known occurrences of more or less complete fossils, but paxilliform primary abactinal ossicles linked by small rods are found among extant stemward genera (Mah, 2005) such as Mediaster Stimpson, 1857. Perhaps also suggesting a stemward position, Marocaster and Mediaster lack the alveolate pedicellariae typical of many more derived goniasterids. In contrast, the robust, nearly equidimensional marginals and apparently at least weakly arched dorsal surface are more derived features (sensu Mah, 2005) that are found in such genera as Tosia Gray, 1840, and Glyphodiscus Fisher, 1917. The unusual expression of the dorsal disk ossicles provide generic apomorphies. Four arm tips of a single specimen, all seemingly in life arrangement, are all that remain of one specimen of M. coronatus. The tips are at the terminus of what appears to be a crawling groove on the bedding plane surface; if so, this is the only fossil in the suite disrupted by a scavenger. Significance of Betelgeusia orientalis n. sp.—Gale (2011) favored assignment of Betelgeusia to the Astropectinidae; assignment to the Radiasteridae is reaffirmed and discussed under ‘‘Betelgeusia, asteroid preservation, and taxonomic approaches.’’ The family Radiasteridae is represented in the modern fauna by the single genus Radiaster, including four species (Clark, 1993; Mah, 2009). Radiaster has been reported from globally widely scattered, deeper water settings, suggesting a relict status. In addition to B. orientalis, fossil

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radiasterids include B. reidi Blake and Reid, 1998, from the Early Cretaceous of Texas; B. exposita Blake and Jagt, 2005, from the Late Cretaceous of northwest Europe; and Indiaster krishna Rao, 1957, from the Middle Jurassic of India. Indiaster was assigned by Rao to the Goniasteridae but it is here transferred to the Radiasteridae. Also, see comments on Dipsacaster jadeti Breton et al. (1995) under Systematic Paleontology. The well-documented setting of B. exposita is considered to represent a high-energy, shallow-water, well-lit environment (Liebau, 1978), and the Mesozoic occurrences together favor a once-wider, shallower-water distribution for the family. With Indiaster, the Radiasteridae joins a number of other surviving families known from Jurassic rocks (see especially Hess, 1972), supporting an early differentiation of the modern fauna. The phylogeny of Blake (1987) assigned the Radiasteridae to a basal position within the Paxillosida, and the comparatively early (Jurassic) occurrence of Indiaster is consistent with a basal position as based on morphology. Molecular phylogenetic analysis would provide further data on radiasterid positioning. Ambulacral and adambulacral ossicles of Texas Cretaceous Betelgeusia reidi are very similar to those of extant Astropecten (Astropectinidae, Paxillosida), suggesting parallel life modes. Ambulacral column expression is incompletely known for the other fossil species, but overall similarities at least suggest ambulacral arrangement likely is similar among all occurrences. Although the functional significance of the distinctive articulation has not been evaluated for extant Astropecten, Blake (1981) posited that the arrangement might reflect arm flexibility, and similar expression in radiasterids might suggest that Astropecten-like flexibility was established quite early in the history of the crown group. Perhaps Astropecten (and similar genera) supplanted radiasterids in appropriate ecologic settings. Expression of the ambulacral column is as yet unavailable for the Astropecten-like Jurassic astropectinid Pentasteria Valette, 1929. MacBride (1921) argued that the unusual characteristics of Astropecten evolved as adaptations to unconsolidated substrates; fossil radiasterids and perhaps Pentasteria document the breadth of MacBride’s adaptive scenario. Significance of Dipsacaster africanus n. sp.—Dipsacaster is a morphologically complex asteroid, and although much is not preserved on the available specimens, the new species is almost entirely in accord with the extended generic diagnosis of Fisher (1911) (see below), although the attenuated arms and inferomarginal spines are distinctive in the new species. Most extant species are from deeper water, (200 m and beyond), although one Japanese occurrence is at 20 m, and others are around 100 m. A Late Cretaceous species, Dipsacaster jadeti, was described by Breton et al. (1995); see comments on this species under Systematic Paleontology. These authors noted similarities between Dipsacaster and other astropectinid genera, as well as the apparently slow rates of morphologic change in certain lineages over extended time intervals; they also noted the comparatively shallow water setting of D. jadeti. In a similar vein, Villier et al. (2007) noted the apparently slow evolution of the Astropectinidae in their description of the new genus Prothrissacanthias. Similarities among Cretaceous and younger taxa also were encountered in the evaluation of fragmentary specimens here (see below), and more broadly, are reflected in the debate over the familial affinities of Betelgeusia.

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Significance of unassigned specimens.—Many fragmentary specimens are scattered on the available blocks, these ranging from the nearly intact to isolated ossicles. Included here are many that might represent either Dipsacaster or Betelgeusia, or plausibly another paxillosidan not recorded by more complete material. Overall form of the marginals and paxillae allow assignment of the fragments at the ordinal level, but similarities of expression in Dipsacaster and Betelgeusia make more precise identification of fragments difficult. A single specimen of a possible zoroasterid is available. It is unfortunate that the specimen is small, and important morphology and taxonomic assessment is difficult. Hess (1974) assigned a new Jurassic fossil, Terminaster, to the Zoroasteridae; based on new material, Villier (2010) reviewed the genus and uncertainties about its morphology, concluding that Terminaster is a plesiomorphic forcipulatacean, but that it cannot be assigned beyond that level. Added discussion is provided by Gale (2011). The present small specimen, although superficially zoroasterid-like, also is of uncertain taxonomic affinities. Two ancient shallow-water occurrences of the family remain; both are Eocene, one from the Antarctic Peninsula (Blake and Zinsmeister, 1977) and the other from New Zealand (Eagle, 2006). SYSTEMATIC PALEONTOLOGY

All specimens are reposited in the collections of the Natural History Museum of Toulouse, France, under prefix MHNT. PAL.2010. Order VALVATIDA Perrier, 1884 Family GONIASTERIDAE FORBES, 1841 Marocaster n. gen. morphology is uniformly typical of the Goniasteridae. Included are overall form, robust, tabulate abactinal ossicles linked by simple basal rods (similar to those of e.g., extant Mediaster); robust, low, rectangular, closely abutted marginal ossicles; closely fitted, square adambulacrals, the ambulacral furrow further closed by a dense spine array; and presence of granules suggesting a surficial dermalgranular layer. Genus MAROCASTER new genus Type species.—Marocaster coronatus n. sp., by monotypy. Etymology.—The French for Morocco, source of known specimens. MAROCASTER CORONATUS new species Figures 1, 2 Diagnosis.—Dorsally arched, stellate goniasterid (Fig. 1.1– 1.3, interbrachia of holotype collapsed); abactinals paxillate, robust, linked at their bases by small rods (Fig. 1.5–1.7). Interbrachials of primary circlet enlarged, shieldlike (Fig. 1.4); first carinal small, second carinal enlarged and elongate, this carinal edged by a smaller abactinal on either side, it abutting the first carinal and an interbrachial (Fig. 1.6). Interbrachial disk ossicles small, uniform. Marginals large, few in number between interbrachial plane and terminal. Superomarginal outline of arm ossicles nearly trapezoidal, intermarginal plane inclined proximally (Fig. 1.1). Ossicular surfaces granulate (Fig. 1.5, 1.6), granules appearing uniform. Actinal fields small, actinal ossicles extending to third inferomarginal; actinals polygonal, varied in size, irregular in shape and arrangement (Fig. 2). Pedicellariae not recognized, spines beyond adambulacrals lacking. Discussion.—Among extant goniasterid genera, rod-like connecting ossicles between the tabulate abactinals are

limited to Rosaster Perrier, 1894, Mediaster, and Nectria Gray, 1840 (Mah, 2005). Marocaster differs from Rosaster and Nectria in overall shape and from Mediaster in marginal form and number. The arrangement of disk abactinals and the form of the superomarginals are unique to Marcroaster. Description.—Five-armed goniasterid; interbrachial arcs broadly rounded, disk large, dorsal surface arched (Fig. 1.1– 1.3); R (available specimens)510.0–11.0 mm, r (partially compacted) 5.0–5.5 mm. R:r approx. 4:1–5:1. Abactinal ossicles uniform, robust, sub-paxilliform, crowns weakly domed, basal facets small; rod-shaped ossicles link paxillae at their bases (Fig. 1.4–1.7). Accessories granulate, densely arranged, suggesting robust dermal-granular layer (Figs. 1.2, 1.3, 1.6, 2). Abactinals not reaching terminal (Fig. 1.1–1.3); carinal series arising at about 4th marginal from arm tip. Carinal series distinct but only slightly enlarged relative to lateral abactinal series (Fig. 1.1, 1.6). Primary circlet consisting of five enlarged, shield-shaped interbrachials and five more weakly enlarged first carinals (Fig. 1.4– 1.7). Enlarged near-proximal carinals aligned with smaller more proximal carinals and first abactinals of first lateral abactinal rows, which are situated between an enlarged proximal carinal and shield-shaped interbrachials. Ossicles within primary circlet ring numerous, smaller but of size similar to ossicles of primary circlet, these somewhat irregular in arrangement (Fig. 1.5–1.7). Two circles of smaller abactinals lie within primary circlet complex, the more outward cycle consisting of nearly 20 ossicles, the inner of about six or seven; a weakly enlarged centrale present. Primary circlet ossicles granulate. Madreporite (Fig. 1.4, 1.5, 1.7) appearing conventional for family; small, polygonal, surface with radiating ridges and grooves, abutting enlarged primary circlet ossicle adradially. Terminal (Fig. 1.1–1.3) proportionately large (possibly reflecting small size of known specimens). Terminal dorsal, elongate, extending to third superomarginal; proximal margin V-shaped; small ambulacral column spines exposed at distal tip below terminal. Marginals in two series, paired where exposed together near tip of arm. Nine marginals present between interbrachial plane and arm tip; size of more distal diminishing abruptly. Marginals robust, rectangular in outline, broader than long. Adradial marginal edges weakly convex; no indication of boundary depression visible along plane of contact between the two marginal series (but this area poorly exposed in available specimens). Dorsal surfaces of superomarginals (ventral surfaces of inferomarginals) flattened, curving more steeply at abradial margin; longitudinal profiles flattened. Contacts between successive proximal and medial superomarginals inclined proximally away from arm midline yielding approximately trapezoidal ossicular outlines; contact planes between other superomarginals and inferomarginals nearly radial (Figs. 1.1–1.3, 2.1, 2.2). Contact surfaces between successive marginals closely abutted, sharply V-shaped but not fasciolate. Outer face finely and uniformly pustulose; no enlarged bosses; remaining granules suggesting uniform dermal-granular layer similar to that of abactinals (Fig. 2.1, 2.2, 2.4). Actinal field small, reaching to third marginal. Actinal ossicles irregular in size, shape, arrangement, especially so near MAO; ossicular surfaces appearing similar to those of other ossicles (Fig. 2.2, 2.4). Adambulacrals small, approximately 25 in number between MAO and upturned arm tip; adambulacral outline

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FIGURE 1—Marocaster coronatus n. gen. n. sp., Taboulouart Formation, Morocco, Early Cretaceous (Barremian), Natural History Museum of Toulouse, France, holotype MHNT.PAL.2010.2.2: 1, specimen in dorsal aspect; 2, 3, inclined views showing body proportions, superomarginal and abactinal form; some granules remain (arrows); 4, inclined view, madreporite beneath an enlarged interbrachial primary circlet ossicle (arrow); 5, arrangement of primary circlet and ossicles within circlet, connecting rods between paxillae (lower arrow); dermal-granular layer at unexposed superomarginal (upper arrow); 6, superomarginal form and granular-dermal layer (left arrow); enlarged carinal paxilla partially enclosed by three proximal paxillae (right arrow); connecting rods visible between carinals, adjacent abactinal row; 7, primary circlet enclosing central ossicles; faceted paxillae with connecting rods (arrow). Scale53 mm for 1–3, 5; 2 mm for 4, 6, 7.

rectangular, weakly transversely elongate; adambulacrals closely fitted longitudinally, capable of closure over furrow. Stepped transverse profile demonstrates differentiation of furrow and subambulacral spinelets; remaining spines (about

four) small, simple, weakly flattened in transverse plane. MAO pair (Fig. 2.3) little enlarged from adambulacrals, ventral outline triangular, MAO pair together forming keellike surface.

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FIGURE 2—Marocaster coronatus n. gen. n. sp.: 1, 3, paratype MHNT.PAL.2010.2.5: 1, complete specimen, actinal interbrachial areas small, some dermal-granular material remains (arrow); 3, central portion of disk, arm to left is at the upward position of 1, mouth angle ossicle pairs (arrows), adambulacral series armor ambulacral furrow; 2, 4, paratype MHNT.PAL.2010.2.4A: 2, complete specimen, dermal-granular material (arrow); 4, central portion of disk and interbrachium, arm to left is at the upper right position of 2, inferomarginals (arrow) border small actinal area. All scales equal 3 mm.

Etymology.—Corona, L, crown, the crown-like form of the primary circlet and the central portion of the disk. Types.—Three essentially complete specimens, Toulouse Museum of Natural History holotype MHNT.PAL.2010.2.2, and paratypes 2010.2.4A and 2010.2.5, are available, along with four arm tips of a fourth, paratype 2010.2.1H, the central portion of the body apparently lost to a scavenger. The ventral surfaces of two of the more intact specimens are exposed, along with the dorsal of the third, which is designated as the holotype. Specimens are assigned to a single species based on uniform size (R,10 mm), outline, and similarity of expression of the two marginal series. Although not exposed together, abactinals and actinals appear compatible in a single goniasterid species. In holotype MHNT.PAL.2010.2.2, the ambulacral columns support the dorsal surface along the arm midlines but the abactinal surface beyond the ambulacra are collapsed into the disk, an event presumably associated with soft tissue decay. There is little or no displacement of primary skeletal elements, including the small rods connecting the abactinals, but abactinal spinelets and most of the granules of the inferred complete granular-dermal layer were lost. Paratypes 2010. 2.4A and 2010.2.5 are partially obscured by what appears to be a mixing of granules of the apparent dermal-granular layer and matrix material. Occurrence.—See Stratigraphic Section and Material.

Discussion.—Maximum size for the species is unknown. The species would be small for the Goniasteridae if available specimens were approaching full size and were not, for example, fortuitously preserved members of a single recruitment class. Order PAXILLOSIDA Perrier, 1884 Family RADIASTERIDAE Fisher, 1916 See comments in Clark (1989) on the correct name for the family. Betelgeusia and Radiaster share an apomorphic expression of the ventral surface: Actinal ossicles are small, flattened, strongly overlapping, tapering toward the tip, and spinose. In the interbrachial arcs, actinals are arranged in a large field of narrow, closely aligned series forming ridges and furrows extending from the marginals toward the ambulacral furrows. Indiaster appears very similar to B. orientalis, although illustrations are incomplete. The three genera also share similarities of overall shape and presence of small and therefore abundant, uniform paxillae, which are aligned in well-defined rows. The madreporite, where known, is nearcentral, unusual in a paxillosidan but perhaps suggestive of a position not too distant from the separation of the Valvatida. Genus BETELGEUSIA Blake and Reid, 1998 Type species.—Betelgeusia reidi Blake and Reid, 1998, by monotypy.

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FIGURE 3—Betelgeusia orientalis n. sp.: 1, holotype MHNT.PAL.2010.2.1A to right, paratypes MHNT.PAL.2010.2.1B–1G numbered progressively to left, 2010.2.1G to upper left; nearly complete block including all seven specimens; specimens 2010.2.1A, 2010.2.1C, and 2010.2.1F show the dorsal surfaces, the remainder the ventral; 2010.2.1D and 2010.2.1G are missing areas of ventral ossicles, other specimens are missing arm tips; 2–9, holotype MNHT.PAL.2010.2.1A: 2, disk area; marginals are robust, paxillae small and aligned in series; 3, central disk, four ambulacral series converge above the sediment-covered mouth frame; madreporite (right arrow), circumoral at head of ambulacral series (left arrow); 4, tip of arm with terminal, also inferomarginals, some with spines; aligned rows of abactinals; 5, 6, profile of superomarginals, rounded in B. orientalis unlike more triangular outline in B. reidi; 7, marginal series with large fascioles; paxillae largely obscured by accessories; 8, displaced abactinals, some with accessories; arrow identifies circumoral to upper right of 1; 9, marginal series, dorsal surface of inferomarginals and lateral IM spine fringe. Scale5100 mm for 1; 10 mm for 2; 3 mm for 3–7, 9; and 2 mm for 8.

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FIGURE 4—Betelgeusia orientalis n. sp.: 1, paratype 2010.2.1B, ventral of disk area; 2, paratype 2010.2.1E, single interbrachium, MAO to right, inferomarginals to left, external odontophore (arrow); 3–6, paratype 2010.2.1D: 3, mid-arm interval, denuded except for inferomarginal spines, actinal series pinching out to left; 4, 5, arrangement of denuded actinals in well-defined series (arrows), also inferomarginals, adambulacrals; skeleton largely lost

BLAKE AND REBOUL—MOROCCAN CRETACEOUS ASTEROIDEA BETELGEUSIA ORIENTALIS new species Figures 3, 4 Diagnosis.—Betelgeusiid with transverse profile of superomarginals rounded (Fig. 3.5, 3.6); actinal accessory spines comparatively small (Fig. 4.2, 4.7). Description.—Five-armed radiasterid; disk large, interbrachia broadly rounded, arms tapering gradually, tips attenuated (Fig. 3.1, 3.4). Abactinals paxillate (Fig. 3.2, 3.8): bases large, elliptical; columns tall, expanding gradually without strong constriction below tip. Dorsal tip of paxilla bearing densely arranged robust spinelets. Paxillae arranged in regular transverse and longitudinal series (Fig. 3.2, 3.4); paxillae series decreasing in number distally, two or three series reaching terminal (Fig. 3.4). Paxillae smaller toward arm tips and marginal frame; locally, paxillae can appear enlarged and aligned along arm midline, probably only because of arched ambulacrals (Fig. 3.4), but otherwise no indication of carinals nor of primary circlet or other abactinal differentiation. Madreporite (Fig. 3.3, right arrow) dorsal, quite large, subcircular, surface of ridges and grooves radiating from well-defined center; madreporite offset slightly from above mouth frame. Marginals of two series paired (Figs. 3.2, 3.9, 4.8), ossicles moderately enlarged; approx. 25 from tip to interbrachial plane in specimen R,56 mm. SMs wider than long interbrachially becoming approximately equidimensional near arm tip. SM dorsal outline tabular, transverse outline gradually sloped adradially, more steeply so near abradial edge; plane of contact between subsequent SMs directed somewhat distally (Fig. 3.4), distinctly fasciolate. Superomarginals finely and evenly granulate, without spines and spinelets; granules slightly spaced, ossicular surface finely pustulate (Figs. 3.9, 4.8). Inferomarginals similar in form to superomarginals; IM ventral surface (Fig. 4.2–4.6) spinose, spines varied in size, bearing distinct fringe of about four large, flattened spines; IM surface pustulate. Actinals (Fig. 4.2–4.7) numerous, tightly overlapping such that most of ossicular surface hidden in life. Ossicles broad, tapering toward slightly enlarged exposed tip; tip bearing spines, these elongate, slender, conical, tapering distally, forming dense pattern on actinal surface (Fig. 4.2, 4.7). Actinals aligned in well-defined narrow series, these separated by fasciolar grooves that are aligned with IM fascioles, two or in places one actinal series aligned with each IM, the second fasciolar groove terminating at IM (Fig. 4.4, 4.5). Actinal series terminating 10 to 15 marginals proximal to arm tip (Fig. 4.3). Adambulacral outer surfaces transversely elongate, perhaps becoming more nearly square distally (Fig. 4.3–4.7). Adambulacral longitudinal cross-section arced so that ossicle overlaps next-distal adambulacral, forming roof over continuation of fasciolar groove to podial basin. Proximal adambulacrals comparatively wide; proximal-most adambulacral strongly overlapping MAO. Adradial podial facet prominent, angular; furrow spines about six, these forming a tight, arced fan (Fig. 4.7); subambulacral series spines more delicate; subambulacral spines similar to those of actinals and smaller of inferomarginal spines; ossicular surface pustulate. About two adambulacrals present for each marginal on arm. Ambulacral adradial end (Fig. 3.3) rectangular in outline, ambulacral-ambulacral articular surfaces upright, not overlapping significantly distally. Dorsal cross-furrow muscle pit deep,

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rectangular. Mouth angle ossicles (Fig. 4.1, 4.2) robust, ventral surface narrow but keel-like; spines quite small, similar to adambulacral spines. Circumoral (Fig. 3.3, left arrow) length slightly greater than that of next distal ambulacral, apparent odontophore exposed on ventral surface between MAO pair (Fig. 4.2, arrow), approximately trapezoidal in outline. Etymology.—Orientalis, Gr., eastern; the type species of Betelgeusia is from Texas and it is the western species whereas B. orientalis is a second (with B. exposita) eastern species. Types.—Toulouse Museum of Natural History MHNT. PAL.2010.2.1A–1G. Seven specimens are available; one specimen is missing one arm and most of the disk and the remainder are missing smaller portions of the arm and disk. Three specimens expose the dorsal surface: R,65 mm, r,27 mm; R,56 mm, r,24 mm; R,45 mm, r,15 mm; and four the ventral: R,32 mm, r,11 mm; R,54 mm, r,25 mm; R,50 mm, r,23 mm; R,34 mm, r,18 mm. The specimens are flattened, the dorsal surfaces within the marginal frame collapsed onto the ventral surfaces and within the frame of the superomarginals. The specimens occur on a single rectangular block (Fig. 1a) of maximum length 58 cm, maximum breadth 20 cm, maximum thickness 3.75 cm. Occurrence.—See Stratigraphic Section and Material. Discussion.—Indiaster krishna Rao, 1957, is here transferred to the Radiasteridae from the Goniasteridae, the familial assignment of Rao. Illustrations in the original publication (see Spencer and Wright, 1966, fig. 56.2) are difficult to evaluate but overall shape, tabular marginals, adambulacral outline, and presence of many small and aligned actinals indicate it is a radiasterid close to Betelgeusia, although marginals appear to be more robust in Indiaster. Type specimens of Indiaster ‘‘are not traceable’’ and ‘‘probably misplaced’’ (Dinesh Srivastava, personal commun., 2009) and therefore detailed comparisons must await rediscovery of the type material or discovery of new material. Differences between the new species and extant Radiaster are shared with B. reidi, as described by Blake and Reid (1998). Ambulacrals and adambulacrals in the new species are not as well exposed; in Betelgeusia adambulacrals appear suggestive of those of Astropecten rather than like the more delicate ossicles of Radiaster, and the marginals of Betelgeusia species are robust as compared to those of Radiaster. In both fossil species, the superomarginals are enlarged relative to the inferomarginals. The distinctive superomarginals of the type species of Betelgeusia are approximately triangular in lateral profile (Blake and Reid, 1998, fig. 8.6) whereas the superomarginals are rounded in B. orientalis (no arm transverse section is available for this species but is best seen in Fig. 3.3, 3.4). In both species, the SM is narrower than the IM and inset from the abradial edges of the latter such that the inferomarginals have dorsally directed spine bosses; however, these bases appear more robust in B. reidi (Blake and Reid, 1998, fig. 8.8). Actinal spines are proportionately shorter in B. orientalis (Fig. 4.2, 4.5, 4.6). Only a portion of the ventral surface of a single specimen of B. exposita is available, and it is comparatively small and therefore potentially misleading in terms of species character expressions. Arms of B. exposita are comparatively short and triangular in outline; the MAO pair is comparatively robust.

r below, a few displaced paxillae remain on 5; 6, accessories of adambulacrals, actinals, inferomarginals; 7, paratype 2010.2.1E, adambulacral spines; inferomarginal accessories around terminus of actinal series; 8, holotype 2010.2.1A, dorsal expression of denuded interbrachial superomarginals and dorsal edge of inferomarginals with lateral spine fringe. Scale55 mm for 1; 3 mm for 2–8.

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FIGURE 5—Dipsacaster africanus n. sp.: 1, 3, holotype MHNT.PAL.2010.2.3A: 1, specimen is folded and partially obscured; paratype 2010.2.3B is to upper left; 3, holotype PAL.2010.2.3A, form and arrangement of paxillae; 2, paratype 2010.2.3B, the only relatively complete ventral surface; most accessories lost. Interbrachial area quite small, actinals robust, irregularly arranged; 4, 5, paratype 2010.2.3E, ventral of incomplete specimen showing

BLAKE AND REBOUL—MOROCCAN CRETACEOUS ASTEROIDEA Family ASTROPECTINIDAE Gray, 1840 Genus DIPSACASTER Alcock, 1893 Type species.—Dipsacaster sladeni Alcock, 1893. Discussion.—Although Cretaceous in age, Dipsacaster africanus is notably similar to living species of the genus. Emphasizing the morphological stability over a long span of geological time, the skeletal portion of the diagnosis of Fisher (1911, p. 85) is quoted below. Those available features of D. africanus n. sp. that are in accord with this diagnosis are in normal type whereas unavailable or incompletely exposed features are italicized. ‘‘Rays five. General form depressed with broad disk and well-developed actinal interradial areas; abactinal surface flat, not arched; marginal plates large, the inferomarginals always broader than superomarginals and typically extending laterally beyond them and forming a subserrate border to ray; fasciolar channels deep and conspicuous, the ridges being correspondingly highly developed; inferomarginals with a tuft of spines at outer end, or these may be exceptionally absent, the superomarginals sometimes with one to three small tubercles; covering of plates ranging from capillary spinelets to polygonal granules; paxilla highly characteristic, composed of a tall pedicel springing from a round or stellate base and crowned with a glomerular tuft of very many slender crowded spinelets; no internal independent ossicles connecting plates; actinal intermediate plates carinated and imbricated, bearing a paxilliform group of spinelets, there being fasciolar channels leading from inferomarginals to adambulacrals; adambulacrals not compressed, with a palmate or pectinate furrow series of cyliindrical or much compressed spines and a variable number of smaller spinelets on exposed surface of plate, the latter usually not regularly arranged; mouth plates prominent actinally, rather broad, with numerous spinules on exposed surface, and a marginal series resembling those of adambulacrals; madreporic body typically very large, hidden by many large paxillae springing from its surface… superambulacral plates always present….’’ In D. africanus, tubercles, if present, are tiny and near the dorsal edge, and the actinals are more pustulose than carinated, although this might reflect differing terminologic usage. Due to collapse and alteration of the single exposed ventral surface of D. africanus, fascioles are poorly exposed but edges of ossicles align with inferomarginals and appear similar to those of extant species. Both capillary spinelets and polygonal granules are present, and both round and stellate bases of the bases of pedicels are present. DIPSACASTER AFRICANUS new species Figure 5 Diagnosis.—A species of Dipsacaster in which the disk appears small as compared to the long, gradually tapering arms and attenuated arm tips (Fig. 5.4). Inferomarginals bearing robust fringe of about three flattened spinelets, ventral surface of ossicle bearing many pointed spinelets of varied length (Fig. 5.4–5.7). Ossicular surfaces pustulose. Abactinals, abactinal spinelets probably relatively robust. Description.—Five-armed asteroid, interbrachia narrowly rounded (Fig. 5.1, 5.2), arms elongate, tapering to pointed tips

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(Fig. 5.4). Abactinals paxilliform, bearing short, robust, conical spinelets (Fig. 5.1, 5.3). Madreporite unknown. Marginals of two series paired, separated by large, deep fascioles with well-developed lateral ridges (Fig. 5.1, 5.2, 5.9). Interbrachial superomarginal breath about 3 times length, ossicles becoming approximately square distally; transverse profile subcircular, longitudinal profile weakly convex to weakly concave, lateral outer face edges sharply rounded, abactinal edge more or less linear. Surface with uniform weakly spaced pustules, these bearing small granules; few SMs might bear very weakly enlarged granules near abactinal edge, but not preserved well enough for clear identification. Interbrachial inferomarginal breadth reaching about 2 times length, unpaired wedge-shape interbrachial IM can occur (Fig. 5.2); lateral edge of IMs extending distinctly beyond adjacent SM (Fig. 5.1, 5.7); dorsally directed portion of IM granulate, abradial edge bordered by fringe of several flattened spines (Fig. 5.6, 5.7). Ventral ossicular surface with many pointed spines of varied length (Fig. 5.4, 5.5). Actinals (Fig. 5.2) rather few, in about four rows, those nearer the MAO appearing distinctly larger, actinals extending to about 5th marginal in available specimen; surfaces pustulose, bearing short, robust spines. Adambulacrals approximately square in outline, bearing palmate furrow row differentiated from subambulacral spines (Fig. 5.5, arrows). Ambulacrals (Fig. 5.1, 5,3, forced through the dorsal midline of the arm) robust, dorsal cross-furrow muscle depression rectangular. Terminal (Fig. 5.8) robust, pustulose, spined; MAO broad, keel-like. Etymology.—Named for the continent of Africa. Types.—Toulouse Museum of Natural History MHNT.PAL. 2010.2.3A–3G. Unlike other specimens in the suite, most specimens of D. africanus are folded, broken, and somewhat overlapping on an area about 125 mm by 90 mm on a single block. Because of breakage, partial burial, and overlap, it is difficult to determine how many specimens are present, but form of exposure suggest four to six individuals. Individual numbers are assigned to seven illustrated specimen fragments representing an uncertain number of specimens; however, unnumbered fragments on the block are a part of the type suite. Occurrence.—See Stratigraphic Section and Material. Discussion.—Clark (1989) and Mah (2009) both listed 15 extant species of Dipsacaster, most occurring in the Pacific Ocean, including Japan, Hawaii, Philippines. The type species is from South Africa and two additional species were described from the Indian Ocean. Although illustrations for many species are limited and many comparisons provide only relative descriptors, Fisher (1919), Macan (1938), and Halpern (1968) provided useful information. The elongate, attenuated arms with a correlated large terminal and the spinose inferomarginals with a robust fringe of flattened lateral spines of D. africanus are distinctive. Proportions of superomarginals appear to differ among species, and the paxillae and paxillary spines of D. africanus appear relatively robust. Based on a single specimen consisting of the dorsal surface of three arms and the central portion of the disk, Breton et al. (1995) recognized a new species assigned to Dipsacaster, D. jadeti. This generic assignment is accepted here, although the small, aligned abactinal ossicles and the mid-dorsal placement

r inferomarginal spines, adambulacral series with furrow spinelets (5, arrows marking adambulacral row), attenuated arm tip; 6, paratype 2010.2.3D; 7, paratypes 2010.2.3C, both 6, 7 showing inferomarginal spine fringes, form of superomarginals, dorsal edges of inferomarginals, marginal granules; 8, paratype 2010.2.3F, arm tip, pustulate terminal with distal spines, eroded distal marginals; 9, paratype 2010.2.3G, abradial view of marginal series, fascioles are deep; a few granules remaining on SM dorsal surfaces. Scale55 mm for 1, 2, 4; 3 mm for 3, 5–9.

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FIGURE 6—1, 2, Order Paxillosida; overall form and ossicles of both specimens suggest D. africanus, although B. orientalis is possible; 1, hypotype MHNT.PAL.2010.2.4B; inferomarginals extend beyond superomarginals (lower arrow), three terminals remain (upper arrow at middle terminal); much disarticulated skeletal debris remains below; 2, hypotype MNHT.PAL.2010.2.8; early ontogenetic specimen with proximal edge of terminal appearing to extend approximately to position of arrow; adambulacrals lie to adradial and extend to mouth frame, no actinals yet visible; 3, Zoroasteridae?, hypotype MNHT.PAL.2.7; dorsal view, arms are weathered and principal arm ossicles appear to be the ambulacrals. Lower right, an isolated paxilla still bearing accessories, either D. africanus or B. orientalis; ossicular base has been lost. Scale52 mm for 1; 0.5 mm for 2; 1 mm for 3.

of the madreporite suggests Betelgeusia or a similar radiasterid. Lacking data on the ventral surface, transfer is not recommended. Placement of D. jadeti exemplifies difficulties encountered in the taxonomic assessment of characteristically incomplete fossil asteroids. Maastrichtian D. jadeti occurs within the known stratigraphic range of both Betelgeusia and Dipsacaster, hence assignment does not affect range of either taxon. Unlike D. africanus, arms of D. jadeti are short and triangular and the interbrachial angles are rounded rather than angular. Both marginals and abactinals appear proportionately smaller than in D. africanus, and the abactinals are aligned in well-defined series. Betelgeusia exposita and D. jadeti are known from the opposite surfaces of only fragmentary specimens; inferomarginal proportions were judged to serve to separate the two (Blake and Jagt, 2005). Order PAXILLOSIDA Figure 6.1, 6.2 In addition to larger specimens listed above, four smaller paxillosidan specimens as well as fragments and clusters of a small number of ossicles are present. Details are not clear enough to assign these fragments to either B. orientalis or D. africanus, nor even to be fully certain whether or not another paxillosidan might be present. Types.—Toulouse Museum of Natural History MHNT.PAL. 2010.2.4B, Fig. 6.1; 2010.2.8, Fig. 6.2; also MHNT.PAL. 2010.2.6, which is not illustrated. Occurrence described under Stratigraphic Section and Material. Order FORCIPULATIDA? Perrier, 1884 Family ZOROASTERIDAE? Sladen, 1889 Figure 6.3 Discussion.—The dorsal surface of a single incomplete very small specimen exhibits an outline, arching of arms and disk, enlarged carinals and marginal ossicles, and arrangement of dorsal disk ossicles strongly suggestive of the family Zoroasteridae. Unfortunately, preservation does not allow certain familial identification. Hypotype.—Toulouse Museum of Natural History MHNT. PAL.2010.2.7. The dorsal surface of disk, two arms, and the bases of the other arms remain. The surfaces appears partially dissolved, probably at the outcrop, exposing the ambulacral ossicles. Occurrence described under Stratigraphic Section and Material.

ACKNOWLEDGMENTS

We are indebted to M. Masrour and I. Z. d’Agadir for identifying the position of the Hauterivian–Barremian boundary. M. Masrour further very kindly clarified aspects of regional and local geology. D. Srivastava provided information on the type material of Indiaster. R. Reboul thanks V. Reboul for her many contributions. J. Jagt and C. Mah provided valuable reviews, and T. Guensburg and S. Hageman provided additional helpful comments. DBB is deeply indebted to the kindness and hospitality of V. and R. Reboul, D. Vizcaı¨no, and B. Lefe`bvre during his visit to France in 2009. REFERENCES

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