Trilobites from the Upper Ordovician of Bou Nemrou ...

BATALLERIA

16

2011

16 - 36

(Barcelona, gener 2011)

ISSN 0214-7831

Trilobites from the Upper Ordovician of Bou Nemrou El Kaid Errami (Morocco) Trilobites del Ordovícico Superior de Bou Nemrou - El Kaid Errami (Marruecos) Joan Corbacho Museo Geológico del Seminario de Barcelona Diputación 231 - 08007 Barcelona. Spain [email protected]

ABSTRACT – Trilobites from the Izegguirene Formation (First Bani Group, Lower Caradoc, Upper Ordovician) of Bou Nemrou (El Kaid Errami, East of Anti-Atlas, Morocco) are described. These comprise the following taxa: Basilicus calzadai sp. nov., Placoparia sp., Eoharpes sp., Zeliszkella (Zeliszkella) velai sp. nov., Degamella sendinoae sp. nov., Uralichas hispanicus tardus (Vela & Corbacho, 2009) and Selenopeltis longispinus (Vela & Corbacho, 2009).

KEY WORDS – Trilobites, Izegguirene Formation, Upper Ordovician, Bou Nemrou, Anti-Atlas, El Kaid Errami, Morocco.

RESUMEN – Se describen y citan todos los trilobites aparecidos en Bou Nemrou (El Kaid Errami, Anti-Atlas oriental, Marruecos) de la formación Izegguirene perteneciente al First Bani Group, Caradoc inferior (Ordovícico Superior), concretamente Basilicus calzadai sp. nov. Placoparia sp., Eoharpes sp., Zeliszkella (Zeliszkella) velai sp. nov., Degamella sendinoae sp. nov., Uralichas hispanicus tardus (Vela & Corbacho, 2009) y Selenopeltis longispinus (Vela & Corbacho, 2009).

Introduction This work describes Moroccan Ordovician trilobites, some species of which have been cited previously: Corbacho (2008), Corbacho & Vela (2010), Vela (2007) and Vela & Corbacho (2007 and 2009). In the present paper I consider all of the trilobites from the Bou Nemrou site and also mention the associated fauna. Later publications will describe other Moroccan Ordovician sites. Trilobites from the Ordovician of the Anti-Atlas (Morocco) have been reported since the beginning of the 20th century. The first authors to study this fauna were Bigot & Dubois (1931 and 1933) followed by Choubert (1942). However, the paper of Destombes (1960) formed the basis of what is known today. (Corbacho & Vela 2010). The specimens studied in this paper are mostly kept at the Geological Museum of the Seminary of Barcelona (abbreviated MGSB), and in Joan Corbacho’s (JC) and Carles Coll’s (CC) private collections.

Geographical location

The studied site (Figs1-6) is located on the summit of the mountain Bou Nemrou. This belongs to the Jbel Tijarfaïouine Massif, in the region of El Kaid Errami (East of Anti-Atlas), Morocco, about 366 kms southeast of Rabat and 25 kms west of Rissani, in the Er Rachidia administrative region. Figs 2-4 show the outcrop. Three excavations were started in 2002 (E1) according to Hda Zamo, the owner son of the land. The coordinates of these excavations are as follows: 1) E1, N 31º 19.509 ‘ - W 004º 31.485 ‘ - Altitude 1045 m. Specimens shown in Figs 3, 5 and 6 come from this site. 2) E2, N 31º 19.518 ‘ - W 004º 31.483 ‘ - Altitude 1049 m. (Fig.4).

3) E3, N 31º 19.546 ‘ - W 004º 31.561 ‘ - Altitude

TRILOBITES FROM THE UPPER ORDOVICIAN OF BOU NEMROU - EL KAID ERRAMI 17 1060 m. This site is still being exploited for fossils. (Fig.4).

The studied site exposes an alternation of sandstones and shales that are included in the First Bani Group, specifically the Izegguirene Fm., because of the presence of Ascocystites sp. (Hunter et al., 2009). Therefore, its age can be considered as Lower Caradoc (Aurelucian).

about 10 cm in thickness, almost parallel to the channels they infill. These layers are massive with the exception of the stage V that is formed by a single sandstone layer of 30 cm thickness. The upper part of each unit consists of shale, which is massive in the lower units (I-III) but shows parallel planar lamination in units IV and V. The lower contacts of the shale layers with the sandstones are abrupt, but parallel bedded apart from unit III where the top of the sandstone comprises rather symmetrical current ripples. The colour of the shales, as already noted, is reddish grey, but it is possible to see some grey stains because of discoloration in units III and IV. Trilobites occur in the sandstones from units IV and I. These are more abundant and more diverse in the lower unit (I). The trilobites are mostly complete, which indicates a lack of post-mortem disintegration.

We have studied in detail an outcrop located in a quarry. This has a wall of 2 metres high with a base (I) (Figure 5) consisting of greenish grey greywacke sandstones with mica, fining upwards ans culminating in reddish grey shales. Above these basal beds are at least four sedimentary units sands with erosive bases (II-V). They have the following thickness visible: I: 40 cm; II: 39 cm; III: 45 cm; IV: 31 cm; and V: 55 cm. As the base of units II to V is clearly erosional, they cut out the shale or sandstone levels from the previous units. Erosion is more intensive in the lower part of the section (Figure 5). The sandstones form more or less continuous layers

It can be concluded that these beds were deposited in a transitional marine environment swept by currents with sufficient energy to erode previously formed units. Once the channels were partially filled by the sandstones, the shales were deposited in lower energies. Significan periods of emersion appear not to have occurred and the reddish colouration can be attributed to processes that happened in the source area of the sediment forming the shale. Through the sequence there is a progressive loss of the erosive power of the currents withtime, with the best preservation in the shale at the base and a smaller incision by the more confined channel.

(This data was recorded recently by me on October 2010 using a GARMIN GPS Model Foretrex 401).

The Outcrop

Figure 1. Site location. A. General map of Morocco. B. Geological sketchmap of the Anti-Atlas (after Destombes et al. 1985; modified). C. Geographical location of the studied section (black star) (after Nardin,2007).

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Figure 2. Bou Nemrou (El Kaid Errami). Excavations indicated by arrows (E1, E2 y E3).

Figure 3. General view of excavation E1, at the Bou Nemrou site, and panoramic view of Jbel Tijarfaïouine.

TRILOBITES FROM THE UPPER ORDOVICIAN OF BOU NEMROU - EL KAID ERRAMI 19

Figure 4. General view of the E2 and E3 excavations at the Bou Nemrou (El Kaid Errami) site. Scale bar 10 cm (E3).

Figure 5. Stratigraphical column of excavation E1 (Izegguirene Fm., First Bani Group) located in Bou Nemrou (El Kaid Errami), Lower Caradoc (Upper Ordovician). Scale bar 25 cm.

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J. CORBACHO in front of glabella. Cephalon surrounded by convex rim; glabella long; preglabellar field narrow; eyes rather large, situated slightly behind transverse mid-line of cranidium; genal angles with spines. Lateral margin of the hypostoma broadly rounded, posterior margin deeply notched. Pygidium with well-defined concave border; inner part of the pygidial pleural fields with strong, rounded ribs; pygidial doublure moderately broad, as in Asaphus”. Assigned species: Basilicus peltastes Salter, 1866. Middle Ordovician of Wales. Basilicus lawrowi Schmidt, 1904. Middle Ordovician of Russia. Basilicus lutsi Öpik, 1937. Middle Ordovician of Estonia.

Figure 6. Geological interpretation of the E1 excavation in Bou Nemrou (El Kaid Errami), exposing the Izegguirene Fm. (First Bani Group) located. In white, sandstones; in grey, shales; grey contours, current rockslides. Scale bar 25 cm.

Systematic palaeontology It is necessary to highlight the palaeontological studies on trilobites from the Moroccan Ordovician published by Bigot & Dubois (1931), Richter & Richter (1943 and 1959), Choubert (1952a, 1952b and 1952c), Choubert et al. (1955), Destombes (1963, 1967a, 1967b and 1972), Destombes et al. (1969), Alberti (1980), Elaouad-Debbaj (1986), El Hassani et al. (1988), Henry (1989), Rábano (1990), Vidal & Henry (1996), Vidal (1996 and 1998), Vela (2007), Vela & Corbacho (2007), Corbacho (2008), Corbacho & Vela (2010), Vela & Corbacho (2009) and Fortey (2009 and 2010). Order ASAPHIDA Salter, 1864 emend. Fortey & Chatterton, 1988 Suborder ASAPHINA Salter, 1864 Superfamily ASAPHOIDEA Burmeister, 1843 Family ASAPHIDAE Burmeister, 1843 Subfamily ASAPHINAE Burmeister, 1843 Genus Basilicus Salter, 1849 Type species: Asaphus tyrannus Murchison, 1839. Llandeilo (Middle Ordovician) of Wales (by original designation). See Fortey (1980) about characteristics of type-species and related species (Sheldon, 1987). Diagnosis – (After Jaanusson, 1959) “Only known genus of Asaphinae with marginal position of facial suture

Basilicus mckeei Ross, 1970. Antelope Valley, Middle Ordovician of Nevada and possibly also Goldwyer Formation, Middle Ordovician of the Canning Basin, Australia (Legg, 1976). Basilicus indet. sp. Vidal, 1998. Lower Ordovician of Morocco. Basilicus? sp. nov. Sá, Rábano & Gutiérrez-Marco, 2006. Middle Ordovician of Portugal. Basilicus vidali Corbacho & Vela, 2010. Lower Ordovician of Morocco. The species name is after the Catalan surname Vidal but no to a specific person, which is the reason why it is vidali and non vidalae. Kobayashi (1934) has also quoted in the Lower Llandeilo from Asia: Basilicus yokusensis, Basilicus deltacaudatus, Basilicus deltacaudus var. tyrannoides, Basilicus sp., Basilicus (?) endoi. Therefore the genus Basilicus includes some species from the Baltic Shield, Laurentia and Gondwana as well as the North Plate of China.

Basilicus calzadai sp. nov. Plate I: Figs 1-3

2006 Basilicus sp. Van Roy, p.23, fig.1.14 b. Taxonomic data - The holotype (Plate I: Figs1a-b) is a complete, well-preserved exoskeleton, kept at the Geological Museum of the Seminary of Barcelona with the registration number MGSB 77680. The paratypes (Plate I: Figs 2-3) are also complete and well preserved, registration numbers JC8 and JC14 in Joan Corbacho’s private collection. This type series comes from excavation E.1 in the Izegguirene Fm. (First Bani Group, Upper Ordovician) of Bou Nemrou (El Kaid Errami).

TRILOBITES FROM THE UPPER ORDOVICIAN OF BOU NEMROU - EL KAID ERRAMI 21 genae are large, prolonged into wide genal tips that are extended until the eighth thoracic segment.

Etymology – This species is named for Dr Sebastián Calzada, Director of the Geological Museum of the Seminary of Barcelona (Spain).

Thorax normal for an asaphid. Its length (sag.) is a third total exoskeletal length, its eight segments parallel andvery similar in shape. The rachis is well defined by dorsal furrows, and measures a quarter of total width (tr). The pleurae contain long and deep furrows that do not rea-

Material and measurements (mm) – There are three specimens, the holotype and two paratypes, in general quite well preserved. Although the holotype has a rebuilt right genal spine and the glabella not well preserved, this

Table 1

CEPHALON - THORAX (mm)

SAMPLE

A

E

F

G

H

PYGIDIUM (mm)

B

C

D

I

J

K

L

M N O

MGSB 77680 42 25

8

85 78 20 15 25 46 75 20 72 20 48 57

JC8

55 36 10 110 86 26 18 30 55 99 26 100 23 65 70

JC14

40 27

8

74 52 16 12 18 35 64 12 64 14 40 45

A = length of cephalon; B = length of glabella; C = length of eyes; D = maximum cephalon width; E = cranidium width at the posterior margin; F = basal width of the glabella; G = glabella width at the frontal lobe; H = genal length of the spine; I = thorax length; J = thorax width; K = rachis width; L = maximum pygidial width; M = anterior width at the pygidial rachis; N = length of the pygidial rachis; and O = length of the pygidium.

is not an impediment for classification nor does it prevent the chose of the specimen as the best in this series. The paratypes are also well preserved. The holotype has a length of 145 mm and the paratypes are 180 mm (JC8) and 120 mm (JC14) long. See Table 1 for measurements. Diagnosis - Species of Basilicus characterized by long and wide genal spines, very long or great preglabellar area, anterior and lateral cephalon borders are placed lower the general plane of trilobite and the thoracic axic is strongly marked. Description - The cephalon outline is ogival. Its length (sag.) is about the same as half of its width (tr.), a little less than a third of total exoskeleton length and smaller than the pygidium. In lateral view, the convexity is moderate. The glabella is smooth and massive, thumbtack-shaped with a frontal lobe slightly rounded and somewhat narrowed at the level of the posterior end of the eyes. The glabella is not well preserved in the holotype. It has a slightly differentiated occipital furrow. The preglabellar area is very great; the anterior and lateral margins of the preglabellar area are lower than the plane of the cephalon (Plate I, fig.1b). The eyes are medium-sized, semicircular and lie just in the posterior half of the cephalon. Eye length (exsag.) represents 20% of cephalon length. The post-ocular segments of the facial suture are strongly sigmoidal and define the narrow fixigenae. The anterior branches of the facial sutures diverge at an angle of 40 degrees, while the divergence is somewhat larger behind the eyes, about 55 - 65 degrees. They form a uniform curve reaching the posterior margin very close to the librigenae at an angle of 45º. Type gonatoparic. The libri-

ch the pleural spines. Pleural spines are curved backwards. The pygidium (macropygidium) is longer than wide with a parabolic outline, its extremity rounded to some extent. It is larger than the cephalon and the thorax. The rachis is well defined, double in width in its anterior part. In the middle and at the end of the rachis there are a series of terrace ridges, scale-like, V-shaped and resembling those of N. nobilis. It has eight rings and a faintly segmented border, with six smooth ribs separated by deep pleural furrows that end abruptly not reaching the peripygidial furrow. There is no pygidial border. Comparison with other species - Differs from the type species in the thoracic axis which in Basilicus calzadai sp. nov. is strongly marked and about half the width of the pleurae. The genal spines of Basilicus calzadai are longer and wider than in the type species and the preglabellar area is wider and positioned lower. Basilicus calzadai sp. nov. lacks a pygidial border. The main difference with Basilicus? sp. nov. (Sá, Rábano & Gutiérrez-Marco, 2006: p. 85) from the Middle Ordovician of Portugal is that the glabella of Basilicus calzadai sp. nov. is narrower than in Basilicus?. In addition, the eyes in Basilicus? are larger than those of Basilicus calzadai sp. nov. The main difference with Basilicus (Basilicus) vidali Corbacho & Vela, 2010 from the Arenig of Morocco is the size, the new species being much smaller. Compared with Basilicus (B.) vidali, the shape of Basilicus calzadai sp. nov. is more elongate, the preglabellar is wider, and the genal spines longer (Corbacho & Vela, 2010).

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Plate I Plate I. Basilicus calzadai sp. nov. from the Izegguirene Fm. (First Bani Group) of Bou Nemrou (El Kaid Errami) (surrounding matrix digitally removed). Scale bar 10 mm. Figs 1a-b, Holotype, MGSB 77680. Fig. 2. Paratype, JC8. Fig. 3. Paratype, JC14.

TRILOBITES FROM THE UPPER ORDOVICIAN OF BOU NEMROU - EL KAID ERRAMI 23 Basilicus calzadai sp. nov. differs from Basilicus sp. Vidal, 1998, from the Arenig of Marruecos, in the lack of a very deep occipital furrow laterally that is subdued in its middle part, the anterior outline of the cephalon has a more triangular shape, and the preglabellar area is wider than in Basilicus sp. Basilicus calzadai sp. nov. differs mainly from species from the Lower Llandeilo of Asia (Kobayashi, 1934) in the curved outline of the cephalon, having a preglabellar area that is wider and lower, and wider genal spines. It is differentiated from Basilicus peltastes Salter, 1866 from the Llandeilo of Wales in having smaller eyes, a wider preglabellar area, longer and wider genal spines, a more broadly rounded pygidium, lacks a pygidial border and less obvious pygidial furrows. Finally Basilicus calzadai sp. nov. differs from Basilicus lutsi Öpik, 1937 from the Ordovician of Estonia mainly in the preglabellar area being not so low and the pygidial outline less rounded. Superfamily CYCLOPYGOIDEA Raymond,1925 Family CYCLOPYGIDAE Raymond,1925 Subfamily CYCLOPYGINAE Raymond,1925 Genus Degamella Marek, 1961 Type species: Aeglina princeps Barrande, 1872. Dobrotivá Formation (Middle Ordovician) of Czech Republic (by original designation). Diagnosis – (After Snajdr, 1990) “Exoskeleton heteropygous, elongated, suboval in ovarall outline; average length 25-55 mm. Cephalon prolonged sagitally, longer than pygidium, strongly vaulted in longitudinal and transversal sections. Glabella extremely large but indistinctly delimited; dorsal furrows shallow, deepest beside the eyes. No occipital furrow, occipital ring fused with glabella. Lateral glabellar muscle scars indicated by colour only (dark markings) or as extremely shallow impresions on the inner exoskeletal side. Occipital impresions: S1 and S2 large and oblique, resembling elongated drops with their broader ends oriented abaxially; S3 rudimentary. Oblong median glabellar node lies between both L2. Fixigena steeply slopes downwards. Eyes relatively small, their exsagittal length is about two fifths of the length of the glabella. Visual surface flat, vertical, longitudinal; anterior and posterior margins rounded. Rostrolibrigenal exoskeletal part large, ventral and partly vertical. Rostral suture strongly arched forwards, forming a half-circle. Hypostoma sagitally short, elongated transversally; wings pointed. Thorax of six segments. Rhachis wide, strongly convex, becomes narrower toward the back. Pleurae furrowed, transversally elongated towards the sixth segment. Pleural tips truncated. Pygidium semicircular in dorsal view, convex, with slightly demarca-

ted conical rhachis. Dorsal furrows very shallow, nearly indistinct. Rhachis reaches two thirds of the pygidium length. Four to five rings are developed: interrig furrows inconspicuous. Lateral pleural lobes almost smooth but one pair of pleurae is sometimes faintly visible. Pygidial border and border furrow narrow; border furrow dies out towards postrhachial area. Pygidial doublure broad, covered by subparallel terrace lines. Sculptation: exoskeleton smooth except for the anterior part of the cephalon with dorsal and ventral sides bearing fine, sparsely distributed waved wrinkles parallel to the cephalic margin.” Assigned species: Degamella gigantea (Barrande, 1872). Ashgill (Upper Ordovician) of Czech Republic. Degamella princeps princeps (Barrande, 1872). Llandeilo (Middle Ordovician) of Czech Republic. Degamella bergeroni (Klouček, 1916). Llarvirn (Middle Ordovician) of Czech Republic. Degamella princeps praecedens (Klouček, 1916). Llarvirn (Middle Ordovician) of Czech Republic. Degamella nuda (Whittard, 1961). Llanvirn (Middle Ordovician) of England. Degamella wattisoni (Hughes, 1979). Llandeilo (Middle Ordovician) of Wales. Degamella evansi Fortey & Owens, 1987. Arenig (Lower Ordovician) of Wales. Degamella famatinensis Esteban, 1996. Tremadoc (Lower Ordovician) of Argentina. Therefore, the genus Degamella has species in both Laurentia and Gondwana.

Degamella sendinoae sp. nov. Plate II: Figs 1-3 Taxonomic data – The holotype and one of the paratypes, both of them cranidia, are housed at the Geological Museum of the Seminary of Barcelona (Plate II, Figs 2-3) with registration numbers MGSB77681 and MGSB77684 respectively. The other paratype (Plate II: Figs1a-c), with a complete exoskeleton, is very well preserved and is number JC46 in Joan Corbacho’s private collection . All of come from excavation E.1 in the Izegguirene Fm. (First Bani Group, Upper Ordovician) of Bou Nemrou (El Kaid Errami). Etymology – This species is devoted to Dr Consuelo Sendino of the Natural History Museum, London (UK). Material and meassurements (mm) – There are three specimens, the holotype and two paratypes. The holotype and one of the paratypes preserve the cranidium and the other paratype almost the entire exoskeleton; all are quite well preserved. Parts of the eyes are present in paratype JC46, which measures 43 mm in length. The other specimens have lengths of 28 mm (MGSB77681) and 25 mm (MGSB77684). See Table 2 for measurements.

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Table 2 SAMPLE JC46 MGSB 77681 MGSB 77684

CEPHALON - THORAX (mm) A B C D E F G 13 13 7 22 14 22 18 X 28 X X X X 24 X 26 X X X X 22

H 8 15 14

PYGIDIUM (mm) I J K 12 22 10 X X X X X X

L 10 X X

A = length of cephalon; B = length of glabella; C = length of eyes; D = maximum cephalic width; E= maximum thoracic length; F = maximum thoracic width; G = basal width of the glabella; H = glabella width at the anterior area; I = maximum rachis width; J = maximum pygidial width; K = anterior width at pygidial rachis; and L = length of pygidium.

Diagnosis – Species of Degamella of half usual size characterized by large eyes and a slightly rectangular cephalon to some extent narrowing frontally. Very rounded and flat pygidium. Description – Exoskeleton elongated lengthwise, approximately twice longer than wide. The cephalon is slightly larger than one-third of exoskeletal length, while the thorax is a little larger than the cephalon and than the pygidium. The cephalon is wider (sag.) than long in its posterior part. Glabella noticeably rounded in the front part and filling most of cephalon. It is narrow at the front and somewhat wider at the back, narrowing abruptly at level of the eyes. Longitudinal and traversely convex, with greater convexity in anterior part. Large eyes extended from the posterior part of the cephalon to more than half of its length, occupying the entire dorsal libriginal surface, convex, the greatest part arranged horizontally. Thorax with six segments. Wide rachis, especially in its anterior part where it is more than half of the total width of the thorax. Almost rectangular, although slightly narrower in its rear part. Axial furrows deep, quite obvious. Pleurae slightly bent backwards, with some wide and very clear articular facets, finishing at tip. Pleura length about half rachis width. Rounded pygidium (subisopygous), two times wider than long. The pygidial rachis is hardly noticeable; it does not have rings. Wide border furrow, not very deep, only defined at the pygidial antero-lateral margins.

pygidial rachis while the type species has a rachis with three very evident segments. Degamella gigantea (Barrande, 1872) from the Ashgill of Czech Republic is a larger trilobite with small eyes relative to the cephalon, while Degamella sendinoae sp. nov. is medium sized and has relatively large eyes compared to cephalon length. Regarding Degamella princeps praecedens (Klouček, 1916) (Marek, 1961: plate IV: figs 8-9) of from the Llanvirn of Czech Republic, the description is very poor since it is based only on the cephalon which is partially preserved. Fortey & Owens (1987) have already questioned the status of the subspecies D. princeps praecedens after the discovery of an almost complete exoskeleton that shows differences with the subspecies D. princeps princeps (Barrande, 1872). Degamella bergeroni (Klouček, 1916) from the Llanvirn of Czech Republic differs from Degamella sendinoae sp. nov. in the cephalon length; in the first species this is longer, and the eyes are very convex. Degamella evansi Fortey & Owens, 1987 from the Arenig of Wales differs from Degamella sendinoae sp. nov. in the cranidium length and the rachis. The first species has a longer cranidium and a very distinct pygicial rachis.

Discussion – Following Fortey & Owens (1987) criteria in regarding Degamella as a genus instead of a subgenus as Marek (1961) established it, this species is assigned to the genus Degamella.

Degamella sendinoae sp. nov. differs from Degamella famatinensis Esteban, 1996 from the Tremadoc of Argentina in the pygidial rachis where it is hard to see any pygidial features, whereas in the Argentinian species this is very well defined. Another difference with Degamella famatinensis is size that is larger in Degamella sendinoae sp. nov. However, the anterior and posterior thoracic rachis is larger in Degamella famatinensis.

Comparison with other species – The new species mainly differs from the type species Degamella princeps (Barrande, 1872) (after Marek, 1961) from the Llandeilo of Czech Republic in having s shorter and more rectangular cephalon outline. As well as this species lacks of

Degamella nuda (Whittard, 1961) from the Llanvirn of England and Degamella wattisoni (Hughes, 1979) from the Llandeilo of Wales, mainly differ in the much more rounded and short cephalon. The thoracic rachis outline is also more triangular than in our species.


Plate II

Plate II. Degamella sendinoae sp. nov. and Zeliszkella (Z.) velai sp. nov. from the Izegguirene Fm. (First Bani Group) of Bou Nemrou (El Kaid Errami) (surrounding matrix digitally removed). Scale bar 10 mm. Figs 1a-1c, Paratype, JC46. Fig. 2, Holotype, MGSB77681. Fig. 3, Paratype, MGSB77684. Fig. 4, Zeliszkella (Z.) velai sp. nov. holotype, MGSB77682.

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Order LICHIDA Moore, 1959 Superfamily LICHOIDEA sensu Fortey (Fortey in Kaesler 1997) Family LICHIDAE Hawle & Corda, 1847 Subfamily LICHINAE Hawle & Corda, 1847 Genus Uralichas Delgado, 1892 (= Platopolichas Gürich, 1901) Type species: There are two opinions on this type species. On the one hand, Rábano (1989: p. 25) cites Lichas hispanica Verneuil & Barrande, 1856 as type species from the Llandeilo of Corral of Calatrava (Spain). On the other hand, Tripp (1957: p. 104) designates Lichas (Uralichas ribeiroi Delgado, 1892 as the type species. This last opinion is also corroborated by Moore (1959: p. O496) on the Treatise on Invertebrates and by other authors like Thomas & Halloway (1988: p.198). As I am not able to study the referred specimens, I cant give an opinion as to which is the correct type species, but I am of the opinion that Rábano (1989) who prepared and studied moulds of the original specimens of Lichas hispanicus and Uralichas ribeiroi is the correct one.

Uralichas hispanicus tardus Vela & Corbacho, 2009 Plate III: Figs 1-2 2009 Uralichas hispanicus tardus Vela & Corbacho, p.100, pl. I: figs 1-3, pl. II: figs 4-6, pl. III: 7-9 Material and measurements (mm) – Two topotypes, JC17 (Plate III: Fig. 1) and CC3 (Plate III: Fig.2). These complete specimens are well preserved and belong to a juvenile and an adult individual. They come from the excavation E1 from the Izegguirene Fm. (First Bani Group, Upper Ordovician) of Bou Nemrou (El Kaid Errami). Housed in the private collections of Joan Corbacho and Carles Coll, they have lengths of 200 mm and 210 mm, respectively. Discussion – In this work I correct the stratigraphical data given by Vela & Corbacho (2009). This subspecies comes from the Izegguirene Fm. (First Bani Group, Upper Ordovician) of the west of Rissani (Errachidia, East of Anti-Atlas). Observations – This species is currently to a great extent forged due to the lack of the big and complete specimens. The adults can reach 400 mm long. They are normally faked by assembling pieces from different indi-

viduals (see Corbacho et al. 2007 and Corbacho & Vela, 2009).

Superfamily ODONTOPLEUROIDEA Sepkoski, 1998 Family ODONTOPLEURIDAE Burmeister, 1843 Subfamily SELENOPELTINAE Hawle & Corda, 1847 Genus Selenopeltis Hawle & Corda, 1847 Type species: Odontopleura Buchii Barrande, 1846 from the Caradoc of Bohemia (by original designation).

Selenopeltis longispinus Vela & Corbacho, 2009 Plate III: Figs 3-4 2009 Selenopeltis longispinus Vela & Corbacho: p. 99, pl. IV: figs 10-12. Material and measurements (mm) – Two complete and very well preserved specimens with a total exoskeleton length of 120 mm for JC19 (Plate III: Fig.3) and 40 mm for JC41 (Plate III: Fig.4). They come from the excavation E1 from the Izegguirene Fm. (First Bani Group, Upper Ordovician) of Bou Nemrou (El Kaid Errami). Discussion – In this work I also rectify the stratigraphical data cited in Vela & Corbacho (2009). This species come from the Izegguirene Fm. (First Bani Group, Upper Ordovician) of the west of Rissani (Errachidia, East of Anti-Atlas).

Order PHACOPIDA Salter, 1864 Suborder CHEIRURINA Harrington & Leanza, 1957 Family PLIOMERIDAE Raymond, 1913 Subfamily PLACOPARIINAE Hupé, 1953 Genus Placoparia Hawle & Corda, 1847 Type species: Trilobites zippei Boeck, 1828. Llandeilo (Middle Ordovician) of Czech Republic (by original designation). Diagnosis – (After Hammann, 1971) Enlarged frontal glabella (tr.). The cheeks form an arc of 45 degrees. Prominent ocular ridges totally or not separated from the cheeks by deep furrows. Lack of eyes. Protoparian facial suture. Small and falciform librigenae that are only for-


Plate III

Plate III. Uralichas hispanicus tardus Vela & Corbacho, 2009 and Selenopeltis longispinus Vela & Corbacho, 2009 from the Izegguirene Fm. (First Bani Group) of Bou Nemrou (El Kaid Errami) (surrounding matrix digitally removed). Scale bar 10 mm. Fig.1, Uralichas hispanicus tardus Vela & Corbacho, 2009, topotype, JC17. Fig. 2, Uralichas hispanicus tardus Vela & Corbacho, 2009, topotype, CC3. Fig. 3, Selenopeltis longispinus Vela & Corbacho, 2009, topotype, JC19. Fig. 4, Selenopeltis longispinus Vela & Corbacho, 2009, topotype, JC41.

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med by the furrow and the lateral border. Frontal furrow from very marked to absent. Lateral margins of the librigenae with pits. Rostrum is small and triangular. Thorax composed of 11-12 segments. Ends of the thoracic segments are pointed and curved downwards forming a right angle with regard to the dorsal plane. Small pygidium; rachis with three or four rings more a small, subtriangular terminal piece. Borders with four convex pleural lobes. Assigned species: Placoparia (Placoparia) cambriensis Hicks, 1875. Upper Arenig and lower Llarvirn of Wales; Llarvirn of Iberian Peninsula (Spain and Portugal), France and Czech Republic. Placoparia (Placoparia) cf. cambriensis Hicks, 1875. Arenig (Lower Ordovician) of Morocco (El-Hassani et al., 1988). Placoparia (Placoparia) zippei (Boeck, 1828). Dobrotivian (Llandeilo, Middle Ordovician) of Czech Republic. Placoparia (Placoparia) cf. zippei (Boeck, 1828). Llandeilo (Middle Ordovician) of Morocco (Destombes, 1971 and Destombres et al., 1985). Placoparia (Placoparia) aff. zippei (Boeck, 1828). Llarvirn of Germany (Hammann, 1971). Placoparia (Coplacoparia) tournemini (Rouault, 1847). Dobrotivian (Llandeilo, Middle Ordovician) of Iberian Peninsula (Spain and Portugal) and France. Placoparia (Coplacoparia) borni Hammann, 1971. Dobrotivian (Llandeilo, Middle Ordovician) of Iberian Peninsula (Spain and Portugal), France and Czech Republic. Therefore the genus Placoparia has been mainly spread through Gondwana, Avalonia and Laurentia.

Placoparia sp. Plate IV: Figs 1-3

Material and measurements (mm) – There are 12 specimens, but only two will be described due to their better preservation. These two specimens have medium size, JC20 (Plate IV: Fig.2) and JC38 (Plate IV: Fig.3) of the Joan Corbacho’s collection. They keep a very well preserved thorax, incomplete pygidium and badly preserved cephalon. The exoskeleton length is of 55 mm for JC20 and 58 mm for JC38. They appeared in the excavations E1, E2 and E3 from the Izegguirene Fm. (First Bani Group, Upper Ordovician) of Bou Nemrou (El Kaid Errami). Description – Specimen JC38 (Plate IV: Figs 3a-c) with rectangular cephalon. In case of the specimen JC20, the cephalon has subtriangular appeareance due to the pressure supported during the fossilization (Plate IV: Fig.1) and whose length is about half of its width or a

fourth part of the total length of the exoskeleton. The glabella is slightly wider in the front part. This one presents three glabellar lobes well differentiated going forward in their most part distal. Narrow preglabellar area. The thorax of the specimen JC20 presents 12 segments, with a well differentiated rachis, the thoracic lateral pleurae end up in tips directed downwards. Rounded pygidium (micropygidium), of smaller size than the cephalon, convex axis with articulating three or four axial rings that can reach the posterior margin of pygidium. This pygidium presents three or four pleural furrows that finish in pygidial tips also directed downwards as the thoracic pleurae. The ventral surface is not preserved and the hypostome badly preserved (Plate IV: Fig.3a). Discussion – It is not possible to assign any of the 12 specimens to a species as they do not keep a cephalon with a complete cephalic front border to count the coaptative devices (vincular furrows). Suborder PHACOPINA Struve, 1959 Superfamily DALMANITOIDEA Vogdes, 1890 Family DALMANITIDAE Vogdes, 1890 Subfamily ZELISZKELLINAE Delo, 1935 Genus Zeliszkella Delo, 1935 Subgenus Zeliszkella s.str. Delo, 1935 Type species: Phacops deshayesi Barrande, 1846. Caradoc (Upper Ordovician) of Czech Republic (by original designation). Diagnosis – (After Struve, 1959) “Cephalon with rather narrow front area, anterior sections of facial sutures close to frontal lobe anteriorly; eyes large, reaching far backward. Posterior thoracic pleurae curving progressively backward, their pointed ends longer than those of anterior pleurae. Pygidium elongate subtriangular with about 10 rings; pleural fields with 3 or 4 ribs”. Assigned species: Zeliszkella deshayesi (Barrande, 1846). Caradoc (Upper Ordovician) of Czech Republic. Zeliszkella (Zeliszkella) hawlei hawlei (Barrande, 1846). Caradoc (Upper Ordovician) of Czech Republic. Zeliszkella (Zeliszkella) torrubiae (Verneuil & Barrande, 1856). Llandeilo (Middle Ordovician) of France and Iberian Peninsula (Spain and Portugal). Zeliszkella (Zeliszkella) lapeyrei Bureau, 1889. Llandeilo (Middle Ordovician) of France and Iberian Peninsula (Spain and Portugal). Zeliszkella (Zeliszkella) toledana (Hammann, 1971). Llandeilo (Middle Ordovician) of Iberian Peninsula (Spain).


Plate IV

Plate IV. Placoparia sp. and Eoharpes sp. from the Izegguirene Fm. (First Bani Group) of Bou Nemrou (El Kaid Errami) (surrounding matrix digitally removed). Scale bar 10 mm. Fig.1, Placoparia sp., complete specimen, JC20. Fig.2, Eoharpes sp., juvenile specimen, JC51. Figs 3a-c. Placoparia sp., specimen JC38 (Fig. 3a hypostome).

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Zeliszkella (Zeliszkella) renaudae Henry, 1980. Llandeilo (Middle Ordovician) of France. Zeliszkella (Zeliszkella) hawlei pandora Snajdr, 1987. Caradoc (Upper Ordovician) of Czech Republic. Consequently the subgenus Zeliszkella (Zeliszkella) has a Gondwanic distribution (France, Spain, Portugal, Czech Republic and Morocco). Observations – Destombes (1972) described Zeliszkella (Zeliszkella) neltneri from the Llandeilo and Zeliszkella (Zeliszkella) zguidensis from the Llarvirn, both of Morocco. After Henry (1980) they belong to the genus Phacopidina Bancroft and to the genus Morgatia Hammann. After Rábano (1989, p. 992 and 994) Zeliszkella lapeyrei (Bureau, 1889, sensu Henry, 1980) must be regarded as a synonym of Zeliszkella (Zeliszkella)torrubiae from the Llandeilo of France and Iberian Peninsula, due to some identical characters.

Zeliszkella (Zeliszkella) velai sp. nov. Plate II: Fig. 4; Plate V: Fig. 1-2 Taxonomic data – The only specimens are the holotype (MGSB77682, Plate V: Fig. 2) and one paratype (JC50, Plate V: Fig. 1). Both of them are whole exoskeleton very well preserved. They are from the excavation E1 from the Izegguirene Fm. (First Bani Group, Upper Ordovician) of Bou Nemrou (El Kaid Errami). Etymology – This species is dedicated to the specialist on Trilobita Dr Antoni Vela, Deapartament de Genètica. Facultat de Biología. Universitat de Barcelona (Spain). Material and meassurements (mm) – The only specimens are those of the type series. The holotype (MGSB77682) has a total length of 36 mm and the paratype (JC50) of 40 mm. The holotype is rolled up (defense), while the paratype is preserved extended. See Table 3 for measurements.

Diagnosis – Species of the subgenus Zeliszkella (Zeliszkella) that is characterized by eyes of relatively medium size and a pit at the centre on the frontal glabellar lobe, just at the distal vertex of the third lateral glabellar furrow (S3). Description – The exoskeleton is almost double long than wide. The cephalon length (sag.) is ¾ of its width (tr.) and represents a little more than the third part of the total exoskeleton longitude, twice (sag.) as much as the pygidium. Cephalon is narrowed towards its distal part, with a subtriangular shape, preglabellar area of médium size. Smooth glabella, slightly enlarged (tr.) at the frontal lobe and faintly convex in lateral view. Big and semicircular eyes, located in the center of the glabella. They do not reach S1 and their posterior ends placed far from the glabella. The cephalon has a circular pit at the centre of the glabellar frontal lobe, just at level of the distal vertex of the third lateral glabellar furrow (S3). Proparian facial sutures. There are an occipital and some glabellar furrows, all of them well defined; S1 faintly descending and tapered in a short perpendicular plane; S2 upwards and S3 again downwards, lengthned and with a gently double inflection towards half way. Small libriginae and they lack of genal tips. Thorax with eleven segments and rachis well defined by dorsal furrows. Pleurae have some long and deep furrows, finishing from behind of some wide articular facets. These ones give a rounded appeareance to the pleural extremes. The thoracic pleura tips are curved back surrounding the pygidium. Subtriangular pygidium (subisopygous), wider (tr.) than longer (sag.); rounded triangular outline; well defined rachis formed by nine rings with three and an half ribs laterally curved back. The pygidial length (sag.) is half of the cephalon length and ¼ smaller than the total exoskeleton lentgh. Almost indistinct pygidial border. Comparison with other species – Differs from the type species [Zeliszkella deshayesi (Barrande, 1846)] because its preglabellar area is more triangular, smaller eyes and the presence of a glabellar pit.

Table 3

CEPHALON - THORAX (mm) SAMPLE A B C D E F G H MGSB 77682 12 10 5 20 20 5 11 17 JC50 14 12 5 20 20 6 12 18

I 18 19

PYGIDIUM (mm) J K L M 6 11 3 6 6 12 4 7

A = length of the cephalon; B = length of the glabella; C = length of eyes; D = maximum cephalic width; E = cranidium width at the posterior margin; F = basal width of the glabella; G = glabella width at the frontal lobe; H = maximum thoracic length; I = maximum thoracic width; J = maximum rachis width; K = maximum pygidial width; L = anterior width at the pygidial rachis; and M = length of the pygidium.

TRILOBITES FROM THE UPPER ORDOVICIAN OF BOU NEMROU - EL KAID ERRAMI 31 Zeliszkella (Zeliszkella) hawlei hawlei (Barrande, 1846) from the Caradoc of Czech Republic differs mainly in that its eyes are bigger; lacks glabellar pit; pygidial outline is much more triangular; and the pygidial margin is also much bigger than in our species. Zeliszkella (Zeliszkella) lapeyrei Bureau, 1889 from the Llandeilo of France and Iberian Peninsula is differenciate in its more triangular cephalon outline; wider glabella at the frontal lobe; presence of two long glabellar pits; bigger eyes, more curved and they are so much far from the glabella in the posterior area; more triangular pygidial outline with a well distinct pydial margin, while Zeliszkella (Z.) velai sp. nov. lacks this margin. Zeliszkella (Zeliszkella) torrubiae (Verneuil & Barrande, 1856) from the Llandeilo of France and Iberian Peninsula differs from our species in bigger eyes; lack of glabellar pit; glabella gets wider strongly; bigger preglabellar area; three and an half ribs at the pygidial rachis, while Zeliszkella (Z.) velai sp. nov. has much less width in the glabella and has four and an half ribs at the pygidial rachis. As well the distance between the terminal rachis tip and the pygidial tip is bigger in Zeliszkella (Z.) torrubiae (Verneuil & Barrande, 1856). Zeliszkella (Zeliszkella) toledana (Hammann, 1971) from the Llandeilo of Spain differs in the exoskeleton is not so elongated; the eyes are much bigger since they reach the level of the occipital furrow; more curved form; and lack of grabellar pit. Zeliszkella (Zeliszkella) renaudae Henry, 1980 from the Llandeilo of France differs mainly in more triangular cephalon outline; wider glabella at the frontal lobe; glabella with two elongated glabellar pits; bigger and more curved eyes; more triangular pygidial tip; existence of pygidial margin, while in our species this margin is almost imperceptible. Zeliszkella (Zeliszkella) hawlei pandora Snajdr, 1987 from the Caradoc of Czech Republic differs principally in bigger eyes; lack of glabellar pit; more triangular pygidial tip; existence of pygidial margin, while our species has an hardly noticeable margin as in the previous species.

(Middle Ordovician) of Osek (Czech Republic). By subsequent designation of Bassler (1915, p. 487). Diagnosis – (After Romano & Henry, 1982). “Cephalon subcircular in outline, convex. Glabella gently convex, highest point at midline of occipital ring, anteriorly depressed below the cheek lobes; basal glabellar lobes small. Eye tubercles small, eye ridges may or may not be present. Alae sub-semicircular, flattened, weakly defined, and depressed below level of cheek lobes. Girder extending to tips of prolongations. External and internal surface of glabella and cheek lobe may show ornament. Cheek-roll prolongation broad, almost parallel sides, with bluntly rounded tip. Brim flat, laterally sloping gently downwards, anteriorly raised dorsally in a low fold. Pits of medium size, irregularly spaced. Hypostoma pear-shaped in outline, with broad anterior and posterior border. Middle body oval in outline, without middle furrow. Thorax with twelve to fifteen segments, width rapidly reduced in the posterior half. Rachis moderatily convex. Pleurae of characteristic harpid from, the outer parts bent vertically down. Pygidium small, outline transverse, three segments only clearly indicated”. Assigned species: Eoharpes primus (Barrande, 1856). Llanvirn (Middle Ordovician) of Czech Republic. Eoharpes benignensis (Barrande, 1872). Llandeilo (Middle Ordovician) of Czech Republic. Eoharpes guichenensis Henry & Philippot, 1968. Llandeilo (Middle Ordovician) of France. Eoharpes cristatus Romano, 1975. Llandeilo (Middle Ordovician) of Portugal. Eoharpes macaoensis Romano & Henry, 1982. Caradoc of Portugal. Eoharpes primus herscheidensis Koch & Lemke 1995. Lower Llanvirn (Middle Ordovician) of Germany. Consequently the genus Eoharpes has mainly been distributed in Gondwana.

Discussion – It is possible to see the basal glabellar lobe of the holotype in detail on Plate V, Fig 2c. This difference with the paratype is because the holotype has its lobe broken. This can lead to confusion and we could be misled into thinking it is a new species.

Eoharpes sp. Plate IV: Fig. 2

Order HARPETIDA Ebach & McNamara, 2002 Suborder HARPINA Whittington, 1959 Family HARPETIDAE Hawle & Corda, 1847 Genus Eoharpes Raymond, 1905 Type species: Harpes primus Barrande, 1856. Llanvirn

Material and meassurements (mm) – There is an only specimen that is rolled up. Therefore it is only possible to see the thoracic dorsal side and ventral side of the librigenae. The exoskeleton is 11 mm long and 10 mm wide. It is from the excavation E1 from the Izegguirene Fm. (First Bani Group, Upper Ordovician) of Bou Nemrou (El Kaid Errami). Currently it is kept in the Joan Corbacho’s private collection with the register number JC51.

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Plate V

Plate V. Zeliszkella (Zeliszkella) velai sp. nov. from the Izegguirene Fm. (First Bani Group) of Bou Nemrou (El Kaid Errami) (surrounding matrix digitally removed). Scale bar 5 mm. Fig. 1, Paratype, specimen JC50. Fig. 2a-b, Holotype, MGSB77682 (Fig. 2b pygidium of the rolled up specimen). Fig.2c The basal glabellar lobe of the holotype (MGSB77682) in detail.

TRILOBITES FROM THE UPPER ORDOVICIAN OF BOU NEMROU - EL KAID ERRAMI 33 Discussion – Henry (1965: p. 207) cites Eoharpes sp. from Armorican Massif, and Henry & Philippot (1968: pp.2187-2189, pl. 1: figs 1-3) described it as Eoharpes guichenensis. Although these two species lived very close to one another, it is not possible to compare with each other because the specimens are not appropriately preserved. The former is kept ventrally rolled up; and the latter lacks of thorax and pygidium.

Conclusions The stratigraphy indicates that the specimens collected in Bou Nemrou (El Kaid Errami, west Anti-Atlas), from the Izegguirene Fm. (First Bani Group, Upper Ordovician), were from not very deep waters, but near the coast. As they are well preserved, it is deduced they has a sudden death and were buried quickly (Corbacho & Vela, 2010). I can tell, from a general point of view, most of of the species of trilobites cited in this paper only appear in Morocco in Bou Nemrou, such as Uralichas hispanicus tardus, Selenopeltis longispinus, Degamella sendinoae sp. nov., Basilicus calzadai sp. nov. and Zeliszkella (Z.) velai sp. nov. It is observed a relationship between the fauna from the Caradoc (Upper Ordovician) of Bou Nemrou ou (El Kaid Errami) and that one from the Llanvirn (Middle Ordovician) of the other Gondwana margin, above all with Bohemia, France and Iberian Peninsula.

Acknowledgements

I am extremely grateful to Dr Richard Fortey (Natural History Museum, London) who has kindly helped me with advice and offered invaluable criticism, with which the work has improved considerably. Thanks also to Claire Mellish and Consuelo Sendino (both from the Natural History Museum, London) for editing the manuscript and helping me with the plates. My most sincere thanks to my colleagues of the Geological Museum of the Seminary of Barcelona who kindly helped me. I also want to thank Brahim and Mhamed Tahiri (Musée Paléontologique Tahirii d’Arfoud, Morocco) and Hda Zamo for their help in the fieldwork; Dr Antoni Vela (Departament de Genètica. Facultat de Biología. Universitat de Barcelona Spain) and Carles Coll for lending specimens.

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Recibido en Junio de 2010 Aceptado en Enero de 2011