A New Genus and Species of Ghost Shrimp from Tobago, West Indies (Crustacea: Decapoda: Callianassidae)

—The new genus Pseudobijfarius is the seventh genus of Callianassinae recognized from the Americas. This monotypic genus is based on its type species from Tobago, West Indies, Pseudobijfarius caesari, new species. It differs from all members of the subfamily in having a very short, stout upper flagellum on the Al peduncle. Collections of a very small callianassid were made on Tobago by two individuals at different times, Lois Nickell in 1989 and Richard Heard in 1992 and 1993. The species was initially identified as a member of Biffarius Manning & Felder, 1991, but closer examination after Heard's collections of 1993 revealed that it represented not only a new species but also a new genus as well. The new taxa are named here. The types have been deposited in the National Museum of Natural History, Smithsonian Institution, Washington, D.C. (USNM). Carapace length (cl) measured as postorbital carapace length and total length (tl), measured on the midlineare in millimeters (mm). Other abbreviations: A l , antennule; A2, antenna; leg., collector; m, meter(s); Maxl-2 , maxillae 1-2; Mxpl -3 , maxillipeds 1—3; P l 5 , pereopods 1-5 (PI and P2 are chelipeds, P3-5 walking legs); P lp l -5 , pleopods 1-5. Family Callianassidae Dana, 1852 Subfamily Callianassinae Dana, 1852 Pseudobijfarius, new genus Type species.—Pseudobijfarius caesari, new species, by present designation and monotypy. Etymology.—The generic name is formed by combining the Latin prefix pseudo-, false, with the generic name Biffarius, alluding to the resemblance of the present genus to the latter The gender is masculine. Diagnosis.—Size relatively small, tl of adults less than 30 mm. Carapace with acute rostral projection, lacking rostral carina or spine. Cornea dorsal, subterminal, diskshaped, corneal elements distinct. Al peduncle longer than A2 peduncle; dorsal flagellum of Al peduncle short and stout, shorter than peduncle. Mxp3 without exopod, ischium-merus operculiform; inner face of ischium with cristate ridge of strong teeth; merus projecting slightly beyond articulation with carpus; last 3 segments slender Chelipeds unequal in male, equal in female, with meral hook. Plpl uniramous in both sexes; Plp2 absent in male, biramous in female; Plp3—5 foliaceus, with stubby, projecting appendices intemae in both sexes. Remarks.—Manning & Felder (1991) recognized and named three American genera in this subfamily, Biffarius, Neotrypaea, and Notiax, and in 1992 added a fourth, Gilvossius. Rodrigues & Manning (1992) added a fifth, Poti. Heard & Manning (1998) added a sixth, Necallianassa. Poti and the type genus of the family, Callianassa Leach, 1814, differ from the remainder of these genera by having slender Mxp3, which are pediform rather than operculiform; Poti also differs from all other VOLUME 113, NUMBER 1 71 genera in the subfamily by having an incomplete linea thalassinica on the carapace. Members of Neotrypaea and Notiax are jcnown only from the eastern Pacific; members of the other genera are known only from the western Atlantic. Members of Pseudobijfarius can be distinguished at once from the American genera with broad Mxp3 by the short, stout dorsal flagellum of Al . They further differ from both Neotrypaea and Gilvossius in having the appendix intemae of the Plp3-5 embedded in the edge of the pleopod, whereas they are projecting in Pseudobiffarius, as in Bif~ farius, Necallianassa and Notiax. In Notiax the second male pleopod is present, whereas it is absent in Pseudobijfarius; members of Notiax also have a strong rostral spine extending almost beyond the cornea and a median distal spine on the telson. Members of Biffarius lack the strong ridge of teeth present on the inner margin of the Mxp3 in members of Pseudobiffarius. Pseudobiffarius caesari, new species Figs. 1, 2, 3a-k, n-o, 4, 5a Material.—Tobago: Lover's Beach, northwest corner of Man O'War Bay [ i r i 9 ' N , 60°34'W], protected beach and shallow reef, depth ca. 2 m, leg. R. Heard, sta 3, 6 Apr 1992: 1 male, cl 3.2 mm (paratype, USNM 260965). Pirate's Cove, east side of Man O'War Bay, depth 2-3 m, leg. R. Heard, 12 Jan 1992: 3 females, 2 non-ovigerous, cl 2.6 and 3.8, 1 ovigerous, cl 4.1 (paratypes, USNM 260970). Buccoo Reef [11°11'N, 60°49'W], back reef area with sand bottom, depth ca. 2 m, leg. R. Heard, sta lOA (1992 sta 2), 11 Jan 1993: 1 male, cl 4.7 mm (holotype, USNM 260966). Coral Gardens, Buccoo Reef, depth 5 m, leg. Lois Nickell, 6 Jul 1989: 1 female, cl 3.6 mm (paratype, USNM 260968).—Coral Gardens, Buccoo Reef, depth 2 m, leg. Lois Nickell, 2 Aug 1989: 1 female, cl 6.0 mm, tl 26 mm (paratype, USNM 260969). Pigeon Point [11°10'N, 60°51'W], depth 1 m, on sand, leg. R. Heard, 15 Jan 1993: 1 female, cl 4.4 mm (paratype, USNM 260967). Lowlands Lagoon [= Petit Trou; 13°50'N, 61°05'W], leg. R. Heard, sta. 9, 7 Apr 1992: 1 male, cl 5.4 m m (paratype, USNM 260971). Diagnosis.—Size very small, cl 6.0 mm or less and tl 30 mm or less in adults. Telson subrectangular, with small submarginal spines posteriorly and distinct median and posterolateral spines. Mxp3 ischium-merus operculiform, without exopod, inner surface of ischium with strong crest of teeth. Major cheliped not dimorphic in males; merus of both chelipeds with ventral hook. Male lacking Plp2. Uropods unarmed. Description.—Carapace (Figs. 1, 4a—c) smooth, with dorsal oval, without cardiac prominence; cervical groove distinct; linea thalassinica distinct, parallel to longitudinal axis of body; rostrum short, acute, not produced into distinct spine; lateral frontal projections present, low, obtuse. Abdominal somites (Figs. 1, 4a, d) smooth, somite 1 saddle-like, shortest; somite 2 longest, almost twice as long as somite 6, with small tuft of setae posterolaterally, set in submarginal longitudinal crease; somites 3—5 subequal in length, each with small lateral row of setae set in submarginal crease; somite 6 about as long as telson, with median carina. Telson (Fig. 4e, f) subrectangular, tapering posteriorly, slightly longer than wide, with anterior tuft of setae mid-dorsally and some isolated setae and small spinules dorsally, submarginal row of spinules present posteriorly; posterior margin setose, emarginate, with median spine and 2 pairs of posterolateral spines. Eyes (Figs. 1, 4a-c, 5a) flattened, slightly convex, about as long as first segment of Al peduncle, external margins moderately convergent, mesial margins parallel, tips pointed; cornea rounded, darkly pigmented, subterminal. Al peduncle (Figs. 4a, b, 5a) extending beyond A2 peduncle; segment 3 more than 72 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON Fig. L Pseudobijfarius caesari, new genus and species, male holotype (USNM 260966), cl 4.7 mm, Buccoo Reef. Lateral view. Scale = 1 mm. twice as long as segment 2, segment 1 subequal to segment 2; upper flagellum stout, much shorter than distal segment of peduncle. A2 peduncle (Figs. 4a, b, 5a) with segment 4 slightly shorter than segment 3 and as long as segment 1 and 2 together; antennal scale not evident; flagellum much longer than peduncle. Mandible (Fig. 3a, b) with numerous small teeth on incisor process; molar process unarmed; palp 3-segmented, segment 3 elongate, longer than segments 1 and 2 combined, tapering distally. Maxl (Fig. 3c) with broad basal endite, distal lobe almost forming right angle; coxal endite elongate, triangular; palp slender, with curved tip. Max2 (Fig. 3d) with protopodal endites bilobed, distalmost lobe elongate, triangular; palp slender; exopod broad, with crenulated margins. Mxpl (Fig. 3e) with protopodal endites very slender, bilobed; palp very small but distinct, longer than wide; exopod bilobed, mesial margin densely setose with short, spatulate setae (Fig. 3f); epipod subrectangular, elongate. Mxp2 (Fig. 3g) with 5-segmented endopod, terminal segment short, spatulate; exopod unsegmented, shorter than endopodal merus; protopod with small setose epipod, apparently lacking arthrobranch. Mxp3 (Fig. 3h-k) ischium-merus sub-operculiform; ischium about as wide as long, mesial surface with dentate crest of large teeth; merus more than 1.5 times wider than long, almost 4 times wider than carpus and propodus, distal margin of outer face projecting beyond articulation with carpus; propodus much longer than wide, tapering distally, only slightly wider than digitiform dactylus. Males with very unequal chelipeds. In larger cheliped of male (Figs. 1, 2a, b): ischium with ventral margin spinulose in largest of 3 males; merus with dorsal margin spinulose in proximal fourth, smooth distally, posterior margin with spinules proximal to distally-directed hook, with distal portion serrated; carpus distinctly longer than wide, smooth dorsally and ventrally, broadly rounded proximally; palm shorter than carpus, length less than height; fingers VOLUME 113, NUMBER 1 73 Fig. 2. Pseudobiffarius caesari, new genus and species, a, Male major PI, outer aspect; b, Male major PI, inner aspect; c, Female P2; d, Male P2; e, Male minor PI; f, Juvenile male minor PI , setae omitted; g, Juvenile male major PI; h, Male P3; i, Female P4; j , Female P5; k, Female Plpl; 1, Female Plp2. a, b, d, male holotype (USNM 260966), cl 4.7 mm, Buccoo Reef; c, g, h, k, 1, female paratype (USNM 260967), cl 4.4 mm. Pigeon Point; e, f, juvenile male paratype (USNM 260965), cl 3.2 mm. Lover's Beach. Scale: a-j, 0.5 mm; k, 1, 1.0 mm. about as long as palm, gaping, tips acutely pointed, crossing; cutting edge of movable finger minutely serrated; gape conspicuous, base with dorsal convex lobe, edge serrate, above smoother, deep invagination in distal border of propodus. Smaller cheliped of male (Fig. 2d, e) and both chelipeds of female (Fig. 2c) similar in size (chelipeds symmetrical in female): ischium smooth, unarmed, about as long as merus; merus with small, acute hook at midlength of ventral margin; carpus longer than Table 1.—Gill formula of Pseudobiffarius caesari, new genus and species. Pleurobranchs Arthrobranchs