JOURNAL OF CRUSTACEAN BIOLOGY, 34(2), 273-282, 2014 DESCRIPTION OF A NEW GENUS AND NEW SPECIES OF SESARMIDAE (DECAPODA: BRACHYURA) FROM THE FARASAN ISLANDS, SAUDI ARABIA, RED SEA Andreas Brösing 1,, Vassily A. Spiridonov 2, Ali M. Al-Aidaroos 3, and Michael Türkay 1 1 Senckenberg Forschungsinstitut und Naturmuseum, Senckenberganlage 25, 60325 Frankfurt am Main, Germany 2 P.P. Shirshov Institute of Oceanology, Nakhimov Avenue 36, Moscow 117997, Russia 3 Faculty of Marine Science, King Abdulaziz University, P.O. Box 80207, Jeddah 21589, Saudi Arabia ABSTRACT A new genus, Eneosesarma, is created for a new species of sesarmid crab, E. azizi, from Saso Island, Farasan Archipelago, Saudi Arabia. The new species shows close affinities with species of the sesarmid genera Sesarmoides Serène and Soh, 1970 and Karstarma Davie and Ng, 2007, but differs from these in regard to carapace shape, morphology of male G1, and absence of stridulatory organ. KEY WORDS: Eneosesarma, Farasan Islands, gastric teeth, gonopods, Red Sea, Sesarmidae DOI: 10.1163/1937240X-00002223 INTRODUCTION Only three species of sesarmid crabs (Holthuis, 1977) have been known to date from the Red Sea, Perisesarma guttatum (A. Milne-Edwards, 1869), Nanosesarma jousseaumei (Nobili, 1906), and Sarmatium crassum Dana, 1851. In this paper, we add a fourth species in a new genus that was collected in abundance during southern Red Sea surveys. The first specimens of our new species were collected by Beat Schätti (Geneva, Switzerland) in December 1989 during a field trip to southern Saudi-Arabia and northern Yemen, including the Farasan Archipelago (Farasan Al- Kebir, Saso, and Sajid). That expedition was mainly devoted to the exploration of the herpetofauna (Schätti and Gasperetti, 1994). One of us (MT) was able to examine the specimens (two females) during a visit to the Muséum d Histoire Naturelle, Genève in 2008, but because there were no males they could not be identified with certainty. During our recent Red Sea Biodiversity Survey 2012 (for details see: www.redseabiodiversity.org) the Farasan Islands were again visited, and we were successful in collecting new material of both sexes of this new taxon, which is herein described. The following abbreviations are used: CL and CW for carapace length and carapace width, respectively, and G1 and G2 for male first and second gonopods. MATERIAL AND METHODS Specimens were collected in the supra-tidal zone along the southern half of the Saudi Arabian Red Sea coast at Saso, Farasan, and Farasan Al- Kebir islands. Most of the specimens were deposited in the collections of Senckenberg Museum, Frankfurt am Main (SMF), with duplicates in King Abdul Aziz University Marine Museum, Jeddah (KAUMM), Queensland Museum, Brisbane (QM), Muséum d Histoire Naturelle de la Ville de Genève (MHNG), and Zoological Museum, Moscow University (ZMMU). Collecting was mainly done by hand. Most specimens were fixed in 70% ethanol, although some were also preserved in 96% ethanol for further genetic analysis. All illustrations were made with a stereomicroscope (LEICA MZ8). Morphometric measurements (Table 1) were made using a caliper with 0.1 mm accuracy. Averages of measured values or ratios are given in Table 1. For scanning electron microscopy, the gastric teeth, G1 and G2 were dehydrated in absolute ethanol and critical-point dried. Finally, they were coated with gold and examined with the digital scanning electron microscope (CamScan, Elektronenoptik GmbH) at the Senckenberg Research Institute, Frankfurt. Photographs were made with digital cameras (CANON 650IS and NIKON D2X) and processed with Adobe Photoshop 7.0. SYSTEMATICS Sesarmidae Dana, 1851 Eneosesarma n. gen. Type Species. Eneosesarma azizi n. sp. (by monotypy). Diagnosis. Lateral borders of carapace convex, lacking teeth behind exorbital angle, posterolateral margins converging; no stridulating apparatus on suborbital margin and cheliped; chela without dorsal pectinated crests; walking legs long and slender; G1 very stout, tip adjacent to distal opening of sperm-channel remarkably truncate and flattened; female genital duct with operculum and lateral rim much elevated beyond sternal surface. Relationships. The new genus is superficially similar to Sesarmoides and Karstarma, with which it shares the general shape of the carapace. The new genus differs from both in the posteriorly converging and unarmed lateral margins, the different morphology of G1, and from Sesarmoides in lacking a tridulating organ (Davie and Ng, 2007). Etymology. A combination of (eneos) in ancient Greek, meaning mute or speechless and Sesarma. The first Corresponding author; e-mail: abroesing@senckenberg.de The Crustacean Society, 2014. Published by Brill NV, Leiden DOI:10.1163/1937240X-00002223
274 JOURNAL OF CRUSTACEAN BIOLOGY, VOL. 34, NO. 2, 2014 Table 1. Average values (standard deviations in parentheses) of Eneosesarma azizi n. gen. and sp. (a sample of specimens from SMF 39213, MHNG and SMF 43475). CB, maximum cephalothorax breadth; CL, maximum cephalothorax length; CH, maximum cephalothorax height; FO, breadth of frontorbital margin of carapace; F, breadth of carapace front; PM, breadth of posterior margin of carapace; P1, length of pereiopod 1 (cheliped) measured along the ventral margin; P2, length of pereiopod 2 measured along the ventral margin; P4, length of pereiopod 4 measured along the ventral margin; LCh, length of chela (right) measured along the ventral margin; HCh, maximum height of chela (right); TCh, maximum thickness of chela (right); N, number of specimens. Characteristics Males Females All specimens N 7 8 15 CB size range 10.0-15.9 11.2-25.0 10.0-25.0 CB/CL 1.28 (0.029) 1.28 (0.036) 1.28 (0.032) CB/CH 2.37 (0.177) 2.31 (0.083) 2.34 (0.133) FO/CB 0.78 (0.041) 0.77 (0.035) 0.77 (0.037) FO/PM 1.66 (0.101) 1.58 (0.080) 1.62 (0.098) F/PM 0.85 (0.044) 0.75 (0.064) 0.78 (0.073) PM/CB 0.47 (0.027) 0.49 (0.020) 0.48 (0.025) P1/CL 1.36 (0.110) 1.27 (0.074) 1.32 (0.100) HCh/CH 0.68 (0.096) 0.56 (0.063) 0.61 (0.100) LCh/HCh 1.99 (0.093) 2.05 (0.175) 2.02 (0.140) LCh/TCh 3.14 (0.147) 3.38 (0.195) 3.28 (0.201) HCh/TCh 1.59 (0.107) 1.66 (0.123) 1.62 (0.117) P4/CB 2.13 (0.132) 2.04 (0.122) 2.08 (0.132) P4/P1 2.01 (0.148) 2.01 (0.119) 2.03 (0.135) P4/P2 1.46 (0.067) 1.45 (0.090) 1.46 (0.077) part of the name refers to the missing stridulating organ. Gender: neuter. Eneosesarma azizi n. sp. Holotype. 1 (SMF 39213), Red Sea, Farasan Archipelago, Sasu Island, 16 51.050 N 41 36.431 E, between rubble, flotsam and jetsam up to two meters above the water line, 21.02.2012, leg. A. Brösing, V. Spiridonov, and A. Alhaj. Paratypes. 5, 7 (SMF 39214); 1 (ZMMU Ma 3474), Red Sea, Farasan Archipelago, Sasu Island, data as in holotype; 2 (MHNG), Red Sea, Farasan Archipelao, Sasu Island, 12.12.1989, leg. B. Schätti. 6, 4 (SMF 43475); 6, 4 (KAUMM 10), Red Sea, Farasan Island, 16 51.864 N, 41 48.645 E, in front of shoreline, 25.02.2012, leg. A. Brösing, S. Tränkner, A. Alhaj and Muaadh Abdo Alnuwairah; 6, 6 (SMF 43476); 5, 5 (KAUMM 11), Red Sea, Farasan Island, 16 52.061 N, 41 48.239 E, between rubble, flotsam and jetsam up to one meter above the water line, 28.02.2012, leg. A. Brösing, A. Alhaj and Muaadh Abdo Alnuwairah; 1, 1 (QM-W29198), Red Sea, Farasan Island, 16 51.864 N, 41 48.645 E, in front of shoreline, 25.02.2012, leg. A. Brösing, S. Tränkner, A. Alhaj and Muaadh Abdo Alnuwairah. Type Locality. Sasu Island, Farasan Archipelago, Saudi Arabia. Etymology. We name this unique species after King Abdul Aziz University in appreciation for the conceptual and financial support of our Red Sea Biodiversity project. Aziz is the abbreviated name broadly used by researchers and students. Diagnosis. As for the genus. Description (based on holotype). Carapace nearly oval with rounded anterolateral and posterolateral margins (Figs. 1, 2, 4A), about 1.3 times as broad as long (Table 1), dorsal surface of carapace slightly convex and smooth; carapace regions weakly defined; frontal region nearly straight, bilobed and of equal size, with shallow median groove separating lobes; gastric region weakly defined, with pair of semi-circular depressions on posterior portion and 2 very small linear depressions on middle part of posterior portion; cardiac region separated from intestinal region by low depression; anterolateral and posterolateral borders smooth; frontal edgeless, broader than posterior edge of carapace; infraorbital margin finely serrated and with 1 triangular spine at median side; exorbital angle with blunt tooth; lateral margin of carapace convex, more or less oval in shape, no teeth behind exorbital angle. Eyestalk relatively short, proximal portion with scattered fine granules, short setae on cornea. Antennules about 4.0 times longer than antenna, folded transversely. Antennae small, basal segment short, antennal flagellum not reaching to proximal margin of cornea. Third maxillipeds with large rhomboidal gap between them; ischium nearly triangular, 1.4 times longer than merus; merus subcircular, with oblique ridge; palp segments short; ischium, merus medially with bristles and dense setae; exopod narrow, not overreaching proximal third of merus, flagellum longer than width of merus, flagellum distally with penicillate hairs (Fig. 4B). Chelipeds (Fig. 3A, B) subequal, relatively small, slightly longer than carapace (Table 1); basi-ischium with 3 pointed tubercles on inner margin; merus smooth, triangular in cross section; inner surface of carpus with 2 sharp teeth; outer surface smooth. Outer surface of palm smooth, inner surface with scattered small and pointed spines. Palm massive, only about 2 times longer than high (Table 1), inner surface smooth, outer surface with a nearly horizontal row of fine granules. Movable finger longer than palm, with small granules proximally on dorsal margin, tips of fingers pectinate, cutting edge of movable finger of male with 4
BRÖSING ET AL.: NEW CRAB IN THE RED SEA Fig. 1. Eneosesarma azizi n. sp. holotype (SMF 39213), male. A, dorsal; B, ventral. Photos by Sven Tränkner (Senckenberg). Scale bar = 2.5 cm. 275
276 Fig. 2. 3 cm. JOURNAL OF CRUSTACEAN BIOLOGY, VOL. 34, NO. 2, 2014 Eneosesarma azizi n. sp. paratype (SMF 39214), female. A, dorsal aspect; B, ventral aspect. Photos by Sven Tränkner (Senckenberg). Scale bar =
BRÖSING ET AL.: NEW CRAB IN THE RED SEA 277 Fig. 3. Eneosesarma azizi n. sp. holotype (SMF 39213, male). A, major chela, outer surface (right); B, major chela, upper surface (right); C, second walking leg (left); D, last walking leg (left).
278 JOURNAL OF CRUSTACEAN BIOLOGY, VOL. 34, NO. 2, 2014 Fig. 4. Eneosesarma azizi n. sp. holotype (A-C) (SMF 39213, male) and paratype (D) (SMF 39214, female). A, dorsal surface of carapace; B, third maxilliped ventral view (left); C, ventral view on male pleon; D, ventral view on female pleon. prominent rounded teeth interspersed with smaller teeth, immovable finger with 2 large teeth interspersed with up to 14 small teeth, inner and outer surface of fingers with simple short bristles. Female cheliped similar to male. Walking legs (Figs. 1, 2, 3C, D) relatively slender and remarkably long, pereiopod 4 longest, about two times longer than cheliped (Table 1); coxae short; basis-ischium short and fused; merus about 4.5 times as long as wide, its distal part with conspicuous notch; distal 0.66 of carpus slightly inclined ventrally; propodus about 3.3 times as long as wide, laterally flattened; dactylus cylindrical, about 8 times as long as wide, slightly curved downwards, with few
BRÖSING ET AL.: NEW CRAB IN THE RED SEA 279 Fig. 5. Eneosesarma azizi n. sp. (A-G) male (SMF 43476), (H, I) female (SMF 39214). A, ventral view on G1; B, lateral view on distal tip of G1; C, enlargement of distal tip of G1; D, dorsal view on G1 with opening for G2; E, ventral view on G2; F, dorsal view on G2; G, view on distal tip of G2; H, ventral view on both female gonopores; I, magnification of panel H. sco, sperm chanal opening; fgo, female genital opening; op, opening for G2; lat, lateral; med, median. Scale bars: A, H = 1 mm, B, D, E, I = 0.3 mm, C, F, G = 0.1 mm. setae and bristles on all surfaces. Dense tufts of setae present between coxae of second and third, and between third and fourth walking legs. Male pleon subtriangular (Fig. 4C), third somite broadest; telson triangular with rounded edges, longer than wide, lateral margin with closely set bristles. Female pleon (Fig. 4D) slightly wider than long, fourth somite broadest, sixth longest; telson triangular with rounded edges, two thirds length of sixth somite, lateral margin with closely set bristles. G1 (Figs. 5A-D, 6A-C, 7A) articulated by joint to intergonopodal bridge; palp absent; distal part relatively short in comparison to Sesarmoides or Karstarma, about 1.7 times longer than G2, distal third half as wide as proximal part, with broad truncate tip and deep groove marking sperm channel reaching from insertion site of G2 to distal opening. Groove accompanying sperm channel exhibits half torsion. Distal opening of sperm-channel nearly circular in shape; surrounded by long setae and bristles, distal part with truncate tip and with a sharp-edged margin. G2 (Figs. 5E-G, 6A) between 0.5 and 0.66 length of G1; proximal width about twice distal width. Distal tip of G2 soft in freshly preserved condition. Female gonopore (Figs. 5H, I, 7B) on anterior edge of sixth sternite with elevated finger-like operculum, wide proximally, becoming narrower distally; mesially with elevated sternal vulvar cover.
280 JOURNAL OF CRUSTACEAN BIOLOGY, VOL. 34, NO. 2, 2014 Fig. 6. Eneosesarma azizi n. sp. (SMF 43476). A, penis, G1 and G2 in their native position; B, right G1 with the functional joint of the G1 and the intergonopodal bridge ; C, distal part of G1 with the groove of sperm channel. G1, First male gonopod; G2, second male gonopod; gsc, groove of sperm channel; igb, inter-gonopodal bridge; op, opening for G2; SCO, sperm channel opening; dashed arrows indicate the movement of G1, single black arrow indicate the joint. Scale bars: A = 0.4 mm; B = 0.35 mm; C = 0.25 mm. Gastric teeth: Lateral teeth: anterior large tooth cusp, followed posteriorly by 8 smaller and mesially directed cusps, lateral side of teeth comprising 14 transverse comblike lamellae (Fig. 8A). Accessory teeth: semicircular row of 9 uniformely elongated single teeth (Fig. 8B). Dorsomedian tooth: situated on postero-ventral part of urocardiac ossicle, consisting of 1 transverse tooth cusp with row of small lateral spines basally (Fig. 8C). Cardio-pyloric- Fig. 7. Eneosesarma azizi n. sp. A, terminal tip of G1 (SMF 43476); B, female sternite six with the gonopore (SMF 39214). Fgo, female genital opening; o, operculum; sco, sperm channel opening; ttg, truncate tip of G1; vc, sternal vulvar cover. Scale bars: A = 0.1 mm; B = 0.6 mm.
BRÖSING ET AL.: NEW CRAB IN THE RED SEA 281 Fig. 8. Gastric teeth of Eneosesarma azizi n. sp. (SMF 39214). A, dorsomedian view on the lateral teeth; B, lateral view on the accessory teeth; C, ventral view on the dorsomedian tooth; D, anterodorsal view on the cardiopyloric valve. At, anterior; cpv, cardio-pyloric valve; ltc, large teeth cusp; pt, posterior; tl, transverse lamellae; ttc, transverse teeth cusp; uo, urocardiac ossicle;, median directed cusps. Scale bars: A, B, D = 0.3 mm; C = 1 mm. valve: antero-dorsally with a remarkable single tooth cusp. Dorsally with subtriangular plate surrounded by brush-like setae (Fig. 8D). Color. Carapace generally light in color, marbled with yellow/orange to brownish patches of variable size. Chelipeds and walking legs yellow to greyish, with pale darker bands. Size. CL = 12 mm, CB = 15 mm (holotype). Otherwise E. azizi is a medium-sized crab. CL/CB in males varies between 5-7 mm (smallest) and 16-20 mm (largest), in females between 4/7 mm (smallest) and 19/ 28 mm (largest). For additional measurements see Table 1. Habitat. The type locality (Saso Island, Red Sea) is characterised by rubble of dried fossil rocks with gaps or crevices, about 1-3 m above the waterline (Fig. 9A). On Farasan Island (Red Sea), the crab was found in small crevices and Fig. 9. Typical habitats of Eneosesarma azizi n. sp. A, type locality, Saso Island; B, Farasan Island.
282 JOURNAL OF CRUSTACEAN BIOLOGY, VOL. 34, NO. 2, 2014 funnels with sandy and rocky ground, at about one meter above, and three meters inland from the waterline (Fig. 9B). Distribution. Known so far only from Sasu and Farasan Island, Farasan Archipelago, Red Sea, Saudi Arabia. DISCUSSION Currently, 31 genera of sesarmid crabs have been described (Ng et al., 2008; Naruse and Ng, 2012). Species of two of them, Sesarmoides and Karstarma show some similarities to the present new species, e.g., long walking legs, absence of stridulatory organ, typically living in caves in limestone (Karstarma); and short bent setae bordering the pterygostomial region (Sesarmoides). Eneosesarma differs from Sesarmoides and Karstarma in having a nearly oval carapace with rounded antero- and posterolateral margins, and in the remarkable shape of the very short G1 (see Brandis et al., 1999), particularly the truncate tip. ACKNOWLEDGEMENTS The scientific research cooperation between King Abdulaziz University (KAU), Faculty of Marine Sciences (FMS), Jeddah, Saudi Arabia, and the Senckenberg Research Institute (SRI), Frankfurt, Germany, in the framework of the Red Sea Biodiversity Project, was funded by KAU GRANT NO. D/1/432-DSR. The authors acknowledge, with thanks, KAU and SRI for technical and financial support. We gratefully acknowledge Peter Davie (Queensland Museum, Brisbane) for reading a first draft of this manuscript and giving us valuable comments. We thank Sven Tränkner for technical support, Christoph Schubart (University of Regensburg) for comments, and Abdulwahid Ganwy (Jeddah) for his guidance and transfer to Sasu Island. Veronika Marschall from the University of Frankfurt helped with advice for the generic name by proposing ancient Greek words. For the language editing of our English we thank GRADE Goethe Graduate Academy, Goethe University Frankfurt am Main. REFERENCES Brandis, D., V. Storch, and M. Türkay. 1999. Morphology and function of the copulatory system in freshwater crabs of the genus Potamon. Journal of Morphology 239: 157-166. Dana, J. D. 1851. On the classification of the Crustacea Grapsoidea. American Journal of Science and Arts (2) 12: 283-291. Davie, P. J. F., and P. K. L. Ng. 2007. A new genus for cave-dwelling crabs previously assigned to Sesarmoides (Crustacea, Decapoda, Brachyura, Sesarmidae). Raffles Bulletin of Zoology Supplement 16: 227-231. Holthuis, L. B. 1977. The Grapsidae, Gecarcinidae and Palicidae (Crustacea: Decapoda: Brachyura) of the Red Sea. Israel Journal of Zoology 26: 141-192. Milne-Edwards, A. 1869. Note sur quelques nouvelles espèces du genre Sesarma (Say). Nouvelles Archives du Muséum d Histoire naturelle 5: 25-31. Naruse, T., and P. K. L. Ng. 2012. Establishment of a new genus for Cyclograpsus lophopus Nobili, 1905, within Sesarmidae Dana, 1851 (Crustacea: Decapoda: Brachyura). Zootaxa 3572: 63-68. Ng, P. K. L., D. Guinot, and P. J. Davie. 2008. Systema Brachyurorum: Part I. An annotated checklist of extant brachyuran crabs of the world. Raffles Bulletin of Zoology 17. Nobili, G. 1906. Diagnoses preliminaires de 34 especes et varietes nouvelles, et de 2 genres nouveaux de Decapodes de la Mer Rouge. Bulletin du Muséum d Histoire Naturelle Paris 11: 393-411. Schätti, B., and J. Gasperetti. 1994. A contribution to the Herpetofauna of southwest Arabia. Fauna of Saudi Arabia 14: 348-423. Serène, R., and C. L. Soh. 1970. New Indo-Pacific genera allied to Sesarma Say 1817 (Brachyura, Decapoda, Crustacea). Treubia 27: 387-416. RECEIVED: 12 November 2013. ACCEPTED: 29 January 2014. AVAILABLE ONLINE: 25 February 2014.