Zootaxa,Diversity within the Ponto-Caspian ...

Zootaxa 1632: 21–36 (2007) www.mapress.com / zootaxa/

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ZOOTAXA

Diversity within the Ponto-Caspian Paramysis baeri Czerniavsky sensu lato revisited: P. bakuensis G.O. Sars restored (Crustacea: Mysida: Mysidae) MIKHAIL E. DANELIYA, ASTA AUDZIJONYTE & RISTO VÄINÖLÄ Finnish Museum of Natural History, POB 17, FI-00014 University of Helsinki, Finland. E-mail: [email protected]; asta.audzijonyte@helsinki,fi; [email protected]

Abstract The Ponto-Caspian mysid crustacean Paramysis bakuensis G.O. Sars, 1895, which was previously synonymized with P. baeri Czerniavsky, 1882, is restored on the basis of new morphological and molecular characters. The Sea of Azov subspecies P. baeri bispinosa Martynov, 1924, in turn, is synonymised with P. bakuensis. The two species, P. baeri and P. bakuensis, are distinguished by the shapes of paradactylar setae of pereiopods, maxilla II exopod and antennal scale, and by the number of denticles in the telson cleft. They also are characterized by ca 7% divergence in mitochondrial COI gene sequences. P. bakuensis is shown to be a widespread species, distributed in estuaries and rivers of the Caspian, Azov and Black Sea basins and in the Caspian Sea itself. P. baeri is endemic to the Caspian Sea, where the two species overlap and are sometimes found together. Key words: Mysida, Caspian Sea, Black Sea, Sea of Azov, Paramysis, taxonomy, endemism

Introduction The Ponto-Caspian basin, which comprises the Black, Azov and Caspian seas and their rivers, is inhabited by a rich endemic brackish-water fauna. This diversity has been intensively explored since the middle of the 19th century, but might still remain underestimated, as few recent taxonomic revisions have been made. For example, recent studies of molecular phylogeography of Ponto-Caspian amphipod and mysid crustaceans revealed deep molecular divergence and cryptic species diversity (Cristescu et al. 2003; Cristescu & Hebert 2005; Audzijonyte et al. 2006). Thirty five species of mysid crustaceans are known from the Ponto-Caspian basin, of which 15 belong to the genus Paramysis Czerniavsky, 1882. The genus itself has a broader distribution that also includes the Mediterranean and low-boreal and subtropical East Atlantic, and in total comprises 23 currently recognized species. The genus Paramysis exhibits considerable morphological diversity which was initially attributed to several genera (Czerniavsky 1882; Sars 1895), later relegated to subgenera (Derzhavin 1939; B|cescu 1954). Accepted by J. Olesen: 21 Sept. 2007; published: 7 Nov. 2007

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The most recent review recognized eight subgenera in the Ponto-Caspian basin alone (Daneliya 2004). The subgenus Paramysis s. str. is morphologically most distinct from the others (Daneliya 2004), and includes three currently accepted species, all endemic to the Ponto-Caspian: P. (P.) baeri Czerniavsky, 1882, P. (P.) eurylepis G.O. Sars, 1907 and P. (P.) kessleri (Grimm in G.O. Sars, 1895) (Derzhavin 1939; Daneliya 2004). The Paramysis type species P. baeri Czerniavsky, 1882, itself encompasses populations with appreciable morphological variation, which has resulted in a confused taxonomic history. Initially, two species were described from the Caspian Sea: P. baeri Czerniavsky, 1882 and P. bakuensis G.O. Sars, 1895, distinguished by their overall habitus, shape of antennal scale, number of denticles in the telson cleft and size of pereiopod merus. Both species were soon also found in the Sea of Azov basin (Sowinsky 1898; Derzhavin 1925), and P. baeri was described there as a separate subspecies P. b. bispinosa Martynov, 1924. Derzhavin soon mentioned that P. b. bispinosa could be a synonym of P. bakuensis, because the major characters of Azovian subspecies (the armature of telson and the shape of antennal scale) are the same specific differences of P. bakuensis from P. baeri (Derzhavin 1926). Later Derzhavin (1939) synonymized P. bakuensis with P. baeri, noting that the original description by Sars (1895) was based on only two juvenile specimens. In fact, in the same study Derzhavin (1939) noted that characters distinguishing the Sea of Azov subspecies P. b. bispinosa from Caspian P. b. baeri were also present in the specimens from Volga river (Caspian basin), and attributed this phenotypic variation to an environmental effect of riverine conditions. Since then, a single species, P. baeri, has therefore been accepted to inhabit the Ponto-Caspian Basin. The Sea of Azov subspecies P. baeri bispinosa nevertheless remained commonly used in literature, and it was also reported from the NW Black Sea estuaries and rivers (e.g. Buchalowa 1929, B|cescu 1954, 1969; Komarova 1991). In a recent mitochondrial DNA analysis of Ponto-Caspian mysids a notably high intraspecific divergence was found within P. baeri sensu lato: two main lineages differed by 7.2% of the nucleotide sites in the CO1 gene (estimated 14% divergence using Kimura-2-parameter + gamma model correction; Audzijonyte et al. 2006). This is clearly higher than the < 3% uncorrected intraspecific differentiation commonly found in other invertebrates (Hebert et al. 2003), and similar to the upper level of intraspecific differences in a review of crustacean data (Lefébure et al. 2006). One of the P. baeri group mitochondrial lineages (”P. cf. baeri I”) was found in the Black Sea, the Sea of Azov basins and in the Caspian Sea basin (Volga river Delta). The other lineage (“P. baeri s. str.”) was found in the Central Caspian Sea only (Audzijonyte et al. 2006). Moreover, another P. baeri s. l. sequence from the Northern Caspian Sea, reported by Cristescu & Hebert (2005) (GenBank AY529030), constituted a third similarly diverged lineage (“P. cf. baeri II”), suggesting even further subdivision in the taxon (Audzijonyte et al. 2006). In this study we examine the morphological differences among samples attributed to P. baeri sensu lato, to evaluate the congruence between morphological and mtDNA differentiation and re-assess the previous suggestions of taxonomic subdivision. Based on these data we restore the species P. bakuensis, re-describe the type species of the Paramysis genus P. baeri and synonymize P.b.bispinosa with P.bakuensis. A morphological key to the four known species of the updated subgenus Paramysis is presented.

Material and methods We examined 69 samples (about 500 specimens) from different parts of the Ponto-Caspian region. Twenty three new samples (about 200 specimens) of P. baeri sensu lato were collected in 1998–2004 from the Sea of Azov, Black Sea and Caspian Sea basins; this material is deposited at the Finnish Museum of Natural History (MZH – Museum Zoologicum Helsinki) and the Zoological Museum of Rostov State University (ZMRSU). In addition, the collections of the Zoological Institute of the Russian Academy of Sciences, St. Petersburg

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(ZIN), the Natural History Museum of the University of Oslo (ZMO), Zoological Museum of the University of Copenhagen (ZMUC) and the Natural History Museum of Humboldt University, Berlin (ZMB) (altogether 45 samples and about 300 specimens) were studied; this material included type specimens of P. baeri and P. bakuensis. We also inspected two specimens from the material studied by Cristescu & Hebert (2005) from the Northern Caspian Sea. A stereomicroscope (Leica Heerbrugg MZ8, magnification 6.3–50x) was used for the initial morphological examination. One to three specimens from each part of the Ponto-Caspian Basin, Central Caspian Sea, Northern Caspian Sea, Volga Delta, the Sea of Azov and Danube Delta, were dissected and put on slides with glycerol-gelatin, and studied by light microscopy (Heerbrugg M11, 24-600x). Ocular micrometers were used to measure body length and ratios of separate body parts. Ratios of parts of thoracopods were measured from slides made for this study (N = 9) and obtained for loan (N = 8). For more efficient comparisons and drawings we also used a Digital FireWire Camera Leica DC 300 with the software Leica IM50 version 1.20. We used the mitochondrial DNA data from Audzijonyte et al. (2006), comprising 19 sequences and 14 haplotypes of a COI gene fragment (605 bp long) of P. baeri s. l., from seven different localities in the Caspian Sea, Volga River, Don River, the Sea of Azov, Kuban River and Danube River (GenBank DQ779856– DQ779869).

Results Several qualitative morphological characters were found to distinguish the two provisionally designated taxa P. baeri s. str. and P. cf. baeri I initially characterized by their mtDNA (Audzijonyte et al. 2006), and that corroborated their status as distinct species. The two taxa showed 7.2–9.0% COI sequence difference and were found in the Central Caspian Sea and the Danube Delta/Azov Sea Basin/Volga Delta, respectively. In most of the additional samples only examined for morphology, the two taxa were found separately. Still in several localities throughout the Caspian Sea they also were recorded together (Fig. 1), but were always easily differentiated from each other, with no intermediate states.

FIGURE 1. Distrubution of Paramysis baeri (white dots) and P. bakuensis (black dots) examined in this study. Grey dots indicate additional records of P. baeri sensu lato according to literature data (Sowinsky 1898; G.O. Sars 1907; Buchalowa 1929; Fadeev 1930; Ilyin 1930; Derzhavin 1926, 1939; B|cescu 1954; Kruglova 1959; Ioffe 1958; Komarova 1991).

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In contrast, no morphological differentiation was found between P. cf. baeri I and the Northern Caspian sample designated as P. cf. baeri II on the basis of its mtDNA, even though they were also distinguished by 7–8% COI divergence. With the lack of morphological distinction and the paucity of molecular data on P. cf. baeri II (two specimens available), we refrain from attributing P. cf. baeri I and P. cf. baeri II to distinct species. The original type series of P. baeri was found to contain specimens representing both P. baeri s. str. and P. cf. baeri I. The type series of P. bakuensis agreed with our P. cf. baeri I and P. cf. baeri II specimens. The specimens of P. baeri bispinosa Martynov, 1924 (ZIN, 6162, 6163, 6164, 6165, 6168) from Don River, used by the author for the description, but not indicated as types, corresponded to the morphology of P. cf. baeri I. Therefore, we keep the name P. baeri Czerniavsky, 1882 for the strictly Caspian taxon P. baeri s. str. and restore P. bakuensis G.O. Sars, 1895 to represent the more widespread species, to include P. cf. baeri I and P. cf. baeri II. P. b. bispinosa is considered a junior synonym of P. bakuensis. Revised descriptions and diagnoses of P. baeri and P. bakuensis are presented below. We give a more detailed description of P. baeri, as it is the type species of the genus.

Taxonomy Mysidae Haworth, 1825 Mysinae Haworth, 1825 Paramysis Czerniavsky, 1882 Paramysis s. str. Czerniavsky, 1882 Paramysis (Paramysis) baeri Czerniavsky, 1882 (Figs 2–5) Paramysis baeri Czerniavsky, 1882: 56 partim; Sars 1893: 403, pl. I, II; 1907: 256, 293 Paramysis (s. str.) baeri Derzhavin 1939: 37 partim Paramysis (Paramysis) baeri Daneliya 2004: 409 partim Paramysis baeri s. str. Audzijonyte et al. 2006: 2974.

Type specimens. Lectotype (+slide), subadult %, 22.5 mm, “Baer, Kaspiiskoe more” (ZIN, 2631). Paralectotype, &, 24.5 mm, “Baer, Kaspiiskoe more” (ZIN, 1/88426). The type series of P. baeri Czerniavsky, 1882 included five specimens, of which two we designated as the lectotype and paralectotype while three others (two % and one &) were identified as P. bakuensis and therefore excluded from the type series (ZIN, 1/88427). The description of Czerniavsky (1882) also refers to additional material that was not assigned a type status. These are: P.(P.) baeri: 9 %, 2 &, 28 juveniles, “Goebel, Kaspiiskoe more, port Astara, 18 m, 24.08.1863” (Southern Caspian Sea) (ZIN, 2633); 2 %, 1 &, “Baer, Kaspiiskoe more, Mangyshlak” (Northern Caspian Sea) (ZIN, 2632) [from the same sample 6 %, 6 &, 1 juvenile identified as P. (P.) bakuensis (ZIN, 2/88428)]; 1 %, “Goebel, Kaspiiskoe more, 1863» (ZIN, 2663). Specimens from the Caspian Sea (Baku), which Czerniavsky (1882, p. 62) designated as Paramysis baeri varietas littoralis and deposited in the Zoological Museum of Odessa University, have been lost, and their identity cannot be established. Type locality. Caspian Sea. Additional material. % and &, Volga delta, Kharbuta ilmen, 45°41´39´´ N, 47°25´18´´ E, 4–5 feet (~1.5 m), mud, 19.06.1904, “Strazha” (ZIN, 5193); 20 % and 9 &, Volga delta, Kharbuta ilmen, 45°40´35´´ N, 47°30´15´´ E, st. 110, N416, about 5/3 m, mud, 19.06.1904, “Strazha” (ZIN); %, st. 110, G.O. Sars (ZMO,


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F12166); 9 %, 7 &, 1 juvenile, Caspian Sea, st. 110, N416 (ZMO, F19746); % (+ slide), G.O. Sars (ZMO, F12165); 2 %, 1 &, Caspian Sea, st. 15, Warpachowsky (ZMO, F19739); &, Caspian Sea, Lonberg (ZMO, F19747); 21 % and 43 &, Caspian Sea, Agrakhan Bay, 06.08.1921, Rustambekova (ZIN); fragment, Caspian Sea, 43°11´ N, 51°17´22´´ E, by Cape Peshchanyi, st. 69, N291, 10 m, sand+shells, 23.05.1904, “Geok-Tepe” (ZIN, 5691); &, Caspian Sea, 45°09´ N, 49°50´30´´ E, st. 19, N74, 9 m, sand+shells, 29–30.03.1904, “GeokTepe” (ZIN, 5686); % and juvenile, Kaspiske Hav (Caspian Sea) (ZMUC, CRU-9900); % (slide), G.O. Sars (NHMUO, F12165); 1 juvenile, Kaspisch. Meer (Caspian Sea) (ZMB, 11286); 13 % and 21 &, Caspian Sea, Dagestan, by Krainovka, shells+mud, 2–4 m, 02.05.2004, Audzijonyte (MZH, 53002; GenBank DQ779856, DQ779857); 2 % (+5 slides of %) and 7 & (+6 slides of &), Caspian Sea, Dagestan, Sulak Bay, from Sulak River mouth to the sea, mud+sand, 4–8 m, 01.05.2004, Audzijonyte (MZH, 53001; GenBank DQ779858, DQ779859, DQ779860); 4 juveniles, Caspian Sea, Dagestan, by Sulak mouth, mud, 8–10 m, 03.05.2004, Audzijonyte (MZH, 53026); %, Caspian Sea, Dagestan, Staroterkskoe, canal, plants, mud, 02.05.2004, Audzijonyte (MZH, 53010); 2 %, Caspian Sea, Dagestan, Audzijonyte (MZH, 53004).

FIGURE 2. Paramysis baeri Czerniavsky, 1882, lectotype, subadult %. Scale 1 mm.

Revised description. Body slender; body length (from tip of subrostral lamina to end of telson) of mature males 13–25 mm, mature females 15–31 mm. Head about as wide as 1st abdominal segment. Subrostral lamina rather long, distinctly protrudes from under the carapace. Carapace: frontal margin convex, smoothly rounded; antero-lateral angles acute; distal margin does not cover the last thoracic segment. Telson longer than the last abdominal segment, tapering distally, 2.1–2.6 times wider proximally than distally; length 2.3–2.5 times the proximal width; cleft small, acute- or right-angled, with 3–11 denticles; lateral margins with 16–23 spine-setae and fine setae. Eyes large, pyriform. Antennular peduncle only slightly shorter than antennal peduncle. Male antennular process large, larger than 3rd segment of antennular peduncle. Antennal scale about twice as long as the antennular peduncle, lanceolate, with a strong outer spine-seta; inner and frontal margins with long setae; frontal margin narrow and almost straight; distal width less than 0.55 of the maximal width (from outer side of base of the spine-seta till outer side of distal segment of the scale); spine-seta advances beyond the distal margin; length 3.1–3.5 times the maximal width. PARAMYSIS BAERI AND P. BAKUENSIS (MYSIDAE)


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FIGURE 3. Paramysis baeri Czerniavsky, 1882, lectotype, subadult %: (a) mandibular palp, medial view; (b) maxilla I, frontal view; (c) maxillipede I, frontal view; (d) maxillipede II, frontal view. Scales 0.5 mm.


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FIGURE 4. Paramysis baeri Czerniavsky, 1882, lectotype, subadult %: (a) telson; (b) antennal scale (without setae); (c) maxilla II, frontal view; (d) pereiopod I, frontal view; (e) pereiopod VI, frontal view; (f) dactylus of pereiopod VI, frontal view. Scales: (a), (b), (c), (d), (e) 0.5 mm, (f) 0.25 mm.



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FIGURE 5. Paramysis baeri Czerniavsky, 1882: (a–c) %, Dagestan; (a) head; (b) penis, medial view; (c) pleopod IV, dorsal view; (d) lectotype, subadult %, endopod of uropod (without setae and statocyst), ventral view. Scales: (a) 1 mm, (b), (c), (d) 0.5 mm.


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Upper labrum smooth, convex. Mandibular palp: 2nd segment 1.7–1.8 times as long as 3rd segment; ventral setae of the 2nd segment quite long, densely set. Maxilla II: exopod rather wide, almost square, width up to 1.3 times the length, with long proximal and short distal setae; proximal setae protrude from the lateral sides of the carapace near pleurocervical fissures; second segment of endopod with setae and one to three frontal spine-setae. Maxillipede I: exopod with 9 segments; preischium endite and ischium endite well-developed; ischium endite larger than the preischium endite; merus length 1.7 times its width. Maxillipede II: exopod with 10 segments; ischium length 1.4–1.7 times its width; merus length 2.0–2.2 times its width; merus length 1.1 times ischium length; carpopropodus 2.0–2.5 times as long as dactylus; dactylar dorsal setae strong, claw-like, strongly serrated; dactylar ventral setae about twice as long as dorsal claw-setae; terminal dactylar claw-setae strongly serrated. Pereiopods: exopod with 9–10 segments; merus of endopod 0.7–0.8 times as long as ischium; carpopropodus with four segments; paradactylar claw-setae with wide, strong denticles. Pereiopod I: preischium with one to three setae; dorsal margin of ischium with central and distal groups of setae; ischium length 2.9–3.6 times its width; merus about the same width as ischium and 0.7–0.8 as long as ischium, with five or six bunches of almost straight ventral setae; merus length 2.5–3.1 times its width; 4th segment of carpopropodus 0.6 of the length of 3rd segment; two or three paradactylar claw-setae with denticles; strong dactylar claw-seta smooth. Pereiopod VI: ischium length 2.7–3.2 times its width; one or two paradactylar claw-setae with strong denticles. Penis with large outer blade and one to three distal long setae; apex with multiple long setae curved inside around gonopore. Pleopods of female reduced, uniramous. Pleopods I, II, V of male reduced, uniramous, pleopod III biramous. Pleopod IV of mature male: endopod reduced, exopod long, with five segments, extends beyond the abdomen, its basis exceeds 6th abdominal segment; 2nd exopod segment the same length as 4th and 5th together; relative lengths of segments 3:2:3.5:1:1. Endopod of uropod with a total of 7–16 spine-setae along one to two thirds of inner margin, with the proximal spine-setae arranged in two rows. Diagnosis. Telson cleft with 3–11 denticles. Frontal margin of antennal scale narrow and almost straight, distal width less than 0.55 of maximum width. Exopod of maxilla II almost square, wider than long. Pereiopod I merus length three times its width. Paradactylar claw-setae of all pereiopods with strong serration. P. baeri differs from P. bakuensis by all above-mentioned characters. From P. eurylepis it differs by the same set of characters and also by narrower antennal scale, which is at least three times as long as wide (less than three times in P. eurylepis); and by the long proximal and short distal setae of the maxilla II exopod (all setae equally long and protruding from the lateral sides of the carapace near pleurocervical fissures in P. eurylepis). P. baeri can not be separated from P. kessleri by the shape of antennal scale, yet it differs by the long proximal setae protruding from the lateral sides of pleurocervical fissures and the short distal setae of maxilla II exopod (all equally short and not protruding in P. kessleri); it also differs by the length of pereiopod I merus, which is 0.7–0.8 of ischium length (almost equal to ischium in P. kessleri); by the shorter 4th segment of the carpopropodus, which is slightly more than a half of 3rd segment (0.7 in P. kessleri); and by spine-setae of uropod endopod that are arranged in two rows proximally (one row in P. kessleri). Molecular characters. P. baeri is characterized by a unique mitochondrial DNA lineage typified by the CO1 gene fragment sequence (GenBank DQ779860), from which all studied conspecific specimens (N = 4; DQ779856–DQ779859) differ by less than 2.5%, whereas divergence from the closest species P. bakuensis is > 7.2% (Audzijonyte et al. 2006). Distribution. Endemic of the Caspian Sea. So far known from the Northern Caspian Sea and western coast of the Central and Southern Caspian Sea (Fig. 1). Habitat. Upper sublittoral (0–20 m). Fresh and oligohaline waters (0–5‰, rarely up to 13‰). Sandy, sandy-muddy bottom (psammophilic). Recorded together with P. kessleri and P. ullskyi, rarely with P. bakuen-



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sis. Evident habitat difference from P. bakuensis has not yet been found, although P. baeri seems to have slightly wider depth range (0–8 m in P. bakuensis). The two species have been found together at several Caspian Sea stations. Both species inhabit the upper sublittoral, in contrast to P. eurylepis, detected at depths from 10 to 114 m. P. kessleri in turn is more eurybiotic, found at depths from 0 m to 114 m (Derzhavin, 1939).

Paramysis (Paramysis) bakuensis G.O. Sars, 1895, stat. rev. (Figs 6, 7) Paramysis bakuensis G.O. Sars, 1895: 437, pl. II, figs. 1–10; Sars 1907 : 257, 293; B|cescu 1934: 335; Paramysis baeri Sowinsky 1898: 377; B|cescu 1934: 335; Paramysis (Paramysis) baeri Derzhavin 1939: 37 partim; Daneliya 2004: 409 partim; Paramysis baeri bispinosa Martynov 1924: 61; Buchalowa 1929: 237; Pauli 1957: 149; Paramysis (Paramysis) baeri bispinosa B|cescu 1954: 114, fig. 45; B|cescu 1969: 374; Komarova 1991: 83; Paramysis cf. baeri I Audzijonyte et al. 2006: 2974; Paramysis cf. baeri II Audzijonyte et al. 2006: 2974.

Type specimens. Lectotype (+slide), subadult &, 11 mm, «Paramysis bakuensis G.O. Sars Mysis relicta Sin. Baku 6 fm VI/1874», Grimm (ZIN, 5694); paralectotype, subadult %, 9 mm, “Paramysis bakuensis G.O. Sars Sin. Baku 6 f, Kaspian Sea”, Grimm (ZMO, F19722). Type locality. Caspian Sea: Southern Caspian Sea near Baku. Additional specimens. 3 % and 7 juveniles, Oblast Voiska Donskogo (Don), 04.08.1919, Martynov (ZIN, 6168); & and juveniles, same district, Siniavskaya (Don Delta), 29.05.1920, Martynov (ZIN, 6162); &, as previous (ZIN, 6163); 1 %, 3 & and 5 juveniles, same district, 15.08.1920, Martynov (ZIN, 6164); 2 % and 2 juveniles, same district, Bagaevskaya (Don), 30.07.–03.08.1919, Martynov (ZIN, 6165); 7 juveniles, same district, Kuterma (Don delta), 19.06.1920, Martynov (ZIN, 42/86846); 1 %, 4 & and 3 juveniles, as previous (ZIN, 11824); juvenile, Don, Rostov-on-Don, 13.07.1913, Derzhavin (ZIN, 37788); 8 juveniles, Sea of Azov, Mariupol, shoreline, N25, 1–1.5 m, mud+sand, 06.09.1914, Derzhavin (ZIN, 37791); many, Sea of Azov, Glafirovskaya spit, st. 406a, N2822, 26.10.1924, Derzhavin (ZIN, 43/86847); juvenile, Sea of Azov, Miusskii liman, 02.09.2003, Audzijonyte (MZH, 53044); 7 juveniles, Kuban delta, Akhtanizovskii liman, 03.09.2003, Daneliya (MZH, 53003; GenBank DQ779867); many (+4 slides of %), Sea of Azov, Taganrog Bay, 25.06.1998, Syrovatka (ZMRSU, slides in MZH), 3 % and & (+6 slides of %, 5 slides of &), Sea of Azov, Taganrog Bay, Morskaya, mud+sand, 1.5 m, 01.07.2001, Daneliya (MZH, 53043); 2 %, Don, by mouth, 24.06.1999, Syrovatka (ZMRSU); 3 juveniles, Don Delta, Mertvyi Donets, 13.09.2003, Daneliya (MZH, 53045; GenBank DQ779865, DQ779866); many adults, Lower Don, Arpachin, 03.07.2001, Daneliya (ZMRSU); 2 &, Lower Don, Razdorskaya, sand, 18.06.1999, Syrovatka (ZMRSU); 2 &, Lower Don, Bagaevskaya, sand, 19.06.1999, Syrovatka (ZMRSU); 3 &, same location, 17.05.2000, Daneliya (ZMRSU); 2 %, 2 &, same location, 05.07.2001, Daneliya (MZH, 53046); &, Lower Don, by Sal River mouth, mud+sand, 17.05.2000, Daneliya (ZMRSU); & and 16 juveniles, Middle Don, Novogrigorevskaya, sand, 20.08.2000, Daneliya (ZMRSU); &, Middle Don, Veshenskaya, sand, 26.08.2000, Daneliya (ZDRSU); & and 4 juveniles, Middle Don, 06.06.2004, Mugue (MZH, 53040); 2 %, & and 8 juveniles (+5 slides of %, 1 slide of &), Volga delta, Damchik, 3–4 m, 18.09.2003, Väinölä (MZH, 53005; GenBank DQ779862, DQ779863, DQ779864); 15 juveniles, same location, 19.09.2003, Audzijonyte (MZH, 53041); 10 juveniles, same location, 09.2003, Daneliya, Audzijonyte (MZH, 53042); juvenile, Volga delta, Rakushechnyi ilmen, 45°46´07´´ N, 47°33´30´´ E, st. 81, N331, 7 m, sand+shells, 03.06.1904, “Strazha” (ZIN, 5696); &, 45°32´30´´ N, 47°45´30´´ E, st. 83, N337, 3 m, sand, 03.06.1904, “Strazha” (ZIN, 5695); % and &, 45°37 N, 47°40´45´´ E, st. 108, N410, 8 feet (~2.5 m), 18.06.1904, “Strazha” (ZIN, 5699); 6 %, 6 & and juvenile, Caspian Sea, Mangyshlak, Baer (ZIN); 46 specimens, Danube delta, Staro-Stambulskoe girlo, st. 12, 8–10 m, 25.08.1958, Zhadin (ZIN, 38267); 3 %, Caspian Sea, Southern Coast, 1877, Baer (ZIN, 2635); 20 juveniles, Caspian Sea, 43°20´45´´ N, 47°42´ E, st.


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77, N313, 19 m, dark grey mud, 30.05.1904, “Strazha” (ZIN, 5697); 5 & and 2 juveniles, Caspian Sea, 42°58´ N, 47°40´ E, st. 89, N355, 22 m, 07.06.1904, “Strazha” (ZIN, 5698); 2 juveniles, Kaspiske Hav (Caspian Sea) (ZMUC); juvenile (slide), G.O. Sars (ZMO, F12167); % (slide), G.O. Sars (ZMO, F12168); % (slide), G.O. Sars (ZMO, F12169); % (slide), G.O. Sars (ZMO, F12170); % (slide), G.O. Sars (ZMO, F12171); 2 juveniles, Kaspisch. Meer (Caspian Sea) (ZMB); %, &, 3 subadult & and juvenile (+ 2 slides of %), Donaudelta (Danube Delta), Lacul Razelm, bei Sarichiei, 44°57´N, 28°52´E, 1.5 m, 17.4oC, 516 ìS/cm, Schlamm, Dreissena, Cardium-Schalen, hohe Trübe, Bodennetz, 31.05.1997, Wittmann (MZH, 53006; GenBank DQ779868, DQ779869; DQ779861 – this sequence was mistakenly attributed to a sample from the Caspian Sea in Audzijonyte et al. 2006); 2 & (+slide of &), Northern Caspian Sea, Russia, 07.2004, Cristescu (MZH, 53028; GenBank AY529030). Revised description. Body stout; body length of mature males 13–26 mm, of females 15–31 mm. Head about as wide as 1st abdominal segment. Subrostral lamina rather long, distinctly protrudes from under the carapace. Carapace: frontal margin convex, smoothly rounded; distal margin does not cover the last thoracic segment. Sternites and last abdominal segment usually almost black in juveniles, rarely in adults. Telson longer than the last abdominal segment, tapering distally; proximal width 2.5–3.2 times distal width; length 2.1–2.5 times proximal width; cleft small, acute- or right-angled, usually with 2 (but sometimes 1–5) denticles and fine setae; lateral margins with 13–20 spine-setae. Antennular peduncle only slightly shorter than antennal peduncle. Antennal scale less than twice the length of the antennular peduncle; distal part rather wide, distal width 0.7–0.8 of maximal width; frontal margin slightly advanced; length 2.7–3.1 times the maximal width. Mandibular palp: 2nd segment 1.7–1.8 times longer than 3rd segment; ventral setae of the 2nd segment quite long, densely set. Maxilla II: exopod rather wide; slightly longer than wide, with long proximal and short distal setae; proximal setae protrude from the lateral sides of carapace at the pleurocervical fissures in dorsal view; second segment of endopod with 9–14 pinnate setae and one to three distal spine-setae. Maxillipede I: merus length 1.5-1.8 times its width. Maxillipede II: ischium length 1.2–1.6 times ischium width; merus length 1.7–2.2 times merus width; merus 1.1–1.2 times as long as ischium; carpopropodus 2.0– 2.7 times as long as dactylus; dactylar dorsal setae strong, claw-like, strongly serrated; dactylar ventral setae about twice as longer as the dorsal claw-setae; terminal dactylar claw-setae strongly serrated. Pereiopods: merus of endopod 0.7–0.8 times as long as ischium; carpopropodus with four segments. Pereiopod I: ischium length 2.5–3.2 times ischium width; merus length 2.2–2.4 times merus width; 4th segment of carpopropodus 0.6 times as long as 3rd segment; one or two paradactylar claw-setae with wide, strong denticles (Fig. 7e). Pereiopods II–VI: paradactylar claw-setae smooth or with fine, hardly visible serration. Pereiopod VI: ischium length 2.4–2.9 times ischium width. Penis with large outer blade and one to three distal long setae. Endopod of uropod with a total of 6–13 spine-setae along one to two thirds of inner margin, with the proximal spine-setae arranged in two rows. Diagnosis. Telson cleft usually with 2 denticles (rarely 1–5), and fine setae. Distal part of antennal scale rather wide, distal width 0.7–0.8 of maximum width; frontal margin slightly advanced. Exopod of maxilla II rather wide, length slightly greater than width. Pereiopod I merus length 2.2–2.4 times merus width. Paradactylar claw-setae of pereiopods II–VI smooth or with fine, hardly visible serration. All the above listed characters differentiate P. bakuensis from P. baeri. P. bakuensis is also morphologically close to P. eurylepis and is distinguished from this species by narrower antennal scale which is approximately three times longer than wide, and by short distal setae of the maxilla II exopod. P. bakuensis differs from P. kessleri by long proximal and short distal setae of the maxilla II exopod, so that long proximal setae protrude from the sides of head next to pleurocervical fissures; by merus of pereiopod I 0.7–0.8 times as long as ischium; the length of 4th segment of carpopropodus, which is 0.6 of 3rd segment length; by the spine-setae of uropod endopod, set in two rows proximally.



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FIGURE 6. Paramysis bakuensis G.O. Sars, 1895: (a, c–e) lectotype, subadult &; (b) &, Volga delta, head; (a) total view; (c) maxillipede I, frontal view; (d) maxillipede II, frontal view; (e) pereiopod I (setae and dactylus missing), frontal view. Scales: (a), (b) 1 mm, (c), (d), (e) 0.25 mm.


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FIGURE 7. Paramysis bakuensis G.O. Sars, 1895: (a, c) lectotype, subadult &; (b, d–g) &, Volga delta; (a) telson (terminal spine-setae missing); (b) telson, distal part; (c) antennal scale, dorsal view; (d) exopod of maxilla II, caudal view; (e) pereiopod I, frontal view; (f) pereiopod VI, frontal view; (g) dactylus of pereiopod VI, frontal view. Scales: (a) 1 mm, (b), (c), (e), (f), (g) 0.5 mm, (d) 0.25 mm.

Molecular characters. P. bakuensis is characterized by a specific mitochondrial DNA lineage typified by a CO1 gene fragment sequence (GenBank DQ779864), from which most conspecific specimens (N = 12; DQ779862–DQ779869) differ by less than 1.2%, whereas divergence from the closest species P. baeri is > 7.2% (Audzijonyte et al. 2006). However, two specimens from Northern Caspian Sea, identified here as P. bakuensis (initially studied by Cristescu & Hebert (2005) and referred to as P. cf. baeri II in Audzijonyte et al. (2006)), have another distinct PARAMYSIS BAERI AND P. BAKUENSIS (MYSIDAE)


33

mtDNA lineage that is equally divergent from the rest of P. bakuensis and P. baeri (c. 7%). The molecular variation in P. bakuensis and possible presence of cryptic species thus require further study. Distribution. Endemic of the Ponto-Caspian basin. Central and Southern Caspian coasts, Northern Caspian Sea, Volga River; the Sea of Azov, Don and Kuban rivers; Danube River (Black Sea basin) (Fig. 1). Habitat. Upper sublittoral (0–8 m). Fresh and oligohaline waters (0–5‰, rarely up to 9‰), rivers up to over 500 km upstream. Sandy, muddy-sandy bottom (psammophilic). Together with P. ullskyi, P. intermedia, occasionally with P. baeri in the Caspian Sea. Remarks. Sars (1895) distinguished P. bakuensis from P. baeri by the overall habitus, the shape and armature of telson, the shape of antennal scale and merus of pereiopods. The body and thoracopods of P. bakuensis are slightly stouter than those of P. baeri. Telson of P. bakuensis is less tapering and usually has two denticles in the cleft, while P. baeri always has more than two denticles. Antennal scale of P. bakuensis is usually more convex distally and concave at the outer margin. Martynov (1924) independently used the same characters to describe the Don River subspecies P. baeri bispinosa. In fact, the difference in the habitus between P. bakuensis and P. baeri in not so easy to see, and the species are hard to distinguish by stoutness alone. The shape of telson and number of denticles in the telson cleft may also mislead due to the occasional overlap. Therefore, after the inspection of large collections from the Caspian Sea, Derzhavin (1939) doubted the distinctness of P. bakuensis as a separate species and synonymized it with P. baeri. The most reliable character that separates the two species is the structure of paradactylar claw-setae of pereiopods. Both species, like other species of the genus Paramysis, have strong denticles on paradactylar claw-setae of pereiopod I. Denticles are also present on paradactylar setae of other pereiopods in P. baeri, but not in P. bakuensis (neither in P. eurylepis and P. kessleri). This might be related to different substrate utilization, although no direct observations exist so far. Additionally, the characters of telson, antennal scale, exopod of maxilla II and merus of pereiopod can be used for the identification.

Key to species of the subgenus Paramysis s. str. of the genus Paramysis Subgeneric diagnosis (updated from Daneliya 2004). Body large. The length of adults exceeds 20 mm. Head about as wide as the first abdominal segment. Frontal margin of carapace convex, smoothly rounded (Figs. 5a, 6a, b). Subrostral plate long. Telson equal to or slightly longer than the last abdominal segment, tapering distally, with fine setae along margins in addition to spine-setae; a small distal cleft armed with few (2 to 11) small denticles; terminal spine-setae long (Figs. 5a, 7a, b). Antennal scale considerably longer than antennular peduncle, about three times longer than wide. The outer spine-seta by the distal end of the antennal scale on the level of frontal margin or slightly beyond it (Figs. 4b, 7c). Mandibular palp with multiple relatively thin setae (Fig. 3a). Endopod of maxilla II with two or three small spine-setae (Fig. 4c). Carpopropodus of all pereiopods 4-segmented (Figs. 4d, c, 7e, f). Paradactylar claw-setae with strong straight denticles (Figs. 4d, c, f, 7e). Penis posterior blade wide with 1–3 long distal setae (Fig. 5b). Spine-setae of uropod endopod occupy more or less proximal part of the appendage (Fig. 5a). 1

-

2

4th segment of carpopropodus of pereiopod I barely more than half as long as 3rd segment (Figs. 4d; 7e); setae of maxilla II exopod long (Figs. 4c, 7d), visible in dorsal view of head in the pleurocervical fissures (Figs. 5a, 6a, b); distal margin of basal segment of thoracopod exopod without setae (Fig. 3c) .............. 2 4th segment of carpopropodus of pereiopod I only slightly shorter than 3rd segment; setae of maxilla II exopod short, invisible in dorsal view of the head in pleurocervical fissures; distal margin of basal segment of thoracopod exopod with long setae .............................................................................................................. ...................... P. (P.) kessleri G.O. Sars, 1895; Caspian Sea, estuaries and rivers of North-West Black Sea Antennal scale relatively narrow, about three times as long as wide (Figs. 4b, 7c); exopod of maxilla II


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3

-

rather wide, with long proximal and short distal setae (Figs. 4c, 7d).......................................................... 3 Antennal scale relatively wide, about 2.5 times as long as wide; exopod of maxilla II oval, with proximal and distal setae equally long ................................................ P. (P.) eurylepis G.O. Sars, 1907; Caspian Sea Paradactylar setae of pereiopod VI strongly serrated, saw-like (Fig. 4e, f); exopod of maxilla II wider than long (Fig. 4c); telson cleft usually with 3–5 denticles (sometimes up to 11) (Fig. 4a) ................................ ................................................................................................P. (P.) baeri Czerniavsky, 1882; Caspian Sea Paradactylar setae of pereiopod VI relatively smooth, without strong serration, saber-like (Fig. 7f, g); exopod of maxilla II not wider than long (Fig. 7d); telson cleft usually with 2 denticles, rarely more (up to 5), and fine setae (Fig. 7a, b).................................................... P. (P.) bakuensis G.O. Sars, 1895; Caspian Sea, estuaries and rivers of the Caspian Sea, the Sea of Azov and North-West Black Sea

Acknowledgements We thank all the curators and other museum personnel who provided material from their collections: Victor Petryashev (ZIN), Åse Wilhelmsen (ZMO), Jørgen Olesen (ZMUC) and Oliver Coleman (ZMB). We also thank Melania Cristescu for the sample from the Northern Caspian Sea, Nikolai Mugue for the sample from the Middle Don, and Karl Wittmann for a Danube sample and for the advice on nomenclature. We also acknowledge those who helped to organize our own fieldwork: E. I. Studenikina and N.I. Syrovatka (Azov Institute of Fisheries, Rostov-on-Don), V.A. Ponomarenko and V.A. Minoranskii (Rostov State University), and A.K. Gorbunov (Astrakhan State Biosphere Natural Reserve). The study was supported by a grant from the University of Helsinki research funds.

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