Synalpheus orapilosus, Hultgren & Macdonald Iii & Duffy, 2010

Hultgren, Kristin M., Macdonald Iii, Kenneth S. & Duffy, J. Emmett, 2010, Sponge-dwelling snapping shrimps of Curaçao, with descriptions of three new species *, Zootaxa 2372 (1), pp. 221-262 : 246-251

Synalpheus orapilosus sp. nov.

( Figs. 14–17 , Pls. 5D–E)

Type material. Holotype: Male, CL 3.17 mm ( USMN 1128427 , original VIMS 08 CU3102) Caracas Baai , Curaçao (12° 04’ 11.64” N, 68° 51’ 43.56” W), in an unidentified white web-like sponge embedded in Madracis sp. rubble, 19.VI.2008 . Allotype: Ov. female, CL 3.23 mm ( USNM 1128428 , original VIMS 08 CU3101,), same data as holotype .

Description. Body subcylindrical; carapace smooth, sparsely setose, posterior margin with distinct cardiac notch. Frontal margin shallow ( Fig. 14 A-C): rostrum clearly narrower than ocular hoods, approximately same length as ocular hoods, distally upturned. Ocular hoods in dorsal view bluntly triangular, separated from rostrum by shallow adrostral sinus; in lateral view distally down turned. Stylocerite with acute tip, very short, length falling well short of distal end of first antennular peduncle. Basicerite without sharp spine-like tooth on dorsolateral corner, and with longer ventrolateral spine extending approximately to distal end of 2 nd peduncle. Scaphocerite blade absent, acute lateral spine robust, approximately equivalent in length to (or slightly longer) than lateral spine of basicerite. Maxilliped 3 ( Fig. 14E , 15E ) with distal segment terminating in cluster of plumose setae, lacking distal circlet of spines (present on all other described West Atlantic gambarelloides group species in the genus Synalpheus with the exception of Synalpheus barahonensis Armstrong ); without ventrodistal spine on antepenultimate segment.

Major pereopod 1 ( Fig. 15 A-C) massive, fingers shorter than half length of palm; in ventral view, outer face of fixed finger without subtle obtuse protuberance. Palm of chela with distal superior margin produced into blunt forward-facing conical tubercle with subtle secondary projection. Merus, extensor margin convex, without distal angular projection.

Minor pereopod 1 ( Fig. 15D ) with palm about 2 times longer than high, fingers shorter than palm; dactyl with flexor margin straight, blade-like, with subdistal accessory protuberance parallel to dactyl axis; transverse dorsal setal combs on extensor surface of dactyl conspicuous. Fixed finger with flexor margin straight, bladelike, and with subdistal accessory bump. Extensor margin of merus convex.

Second pereopod ( Fig. 14D ) with carpus 5-segmented, slightly longer than merus.

Third pereopod ( Fig. 16A, B ) dactyl biunguiculate, with clearly unequal teeth; flexor tooth wider at base than extensor tooth; propodus with 5 mobile spines on flexor margin and 1 pair on distal end; carpus with 1 mobile distal spine on flexor margin; merus without any spine on flexor margin. Fourth pereopod ( Fig. 16C, D ) similar to third, but with 4 mobile spines on flexor margin. Fifth pereopod ( Fig. 16E, F ) similar to fourth, but with 2 long rows of transverse setae on flexor margin.

Pleura 1 of male ( Fig. 17B ), ventral margin strongly concave, with posterior corner distinctly produced ventrally and anteriorly, strongly hook-like; anterior corner produced ventrally into a rounded acute corner. Second pleura of male with lower margin sloping posteriorly to a rounded acute posterior corner. Third to fifth pleura similar to second, with posterior margin of each forming a rounded acute corner.

Telson ( Fig. 17D ), dorsal spines stout, uropods with single fixed tooth on outer margin of exopod anterior to moveable spine ( Fig. 17C ).

Color. Live specimens are drab; ovigerous females have dull green embryos and ovaries.

Etymology. This species name is derived from the Latin terms “hairy” (pilosus) and “mouth” (ora) to denote the distinctive character –a third maxilliped with a distal tuft of setae instead of a distal circlet of spines—that distinguishes this species from all other known West Atlantic species of Synalpheus with the exception of S. barahonensis , (see Remarks).

Hosts and ecology. The single pair of S. orapilosus was found in an unidentified white webby sponge in Caracas Baai, one of the most species-rich sites we surveyed. This sponge was rare elsewhere despite intensive searching.

Distribution. Curaçao (this study).

Remarks. Synalpheus orapilosus is morphologically most similar to Synalpheus barahonensis , originally described from the Bahamas and the only other gambarelloides group Synalpheus distinguished by a tuft of setae on the distal end of the third maxilliped (instead of a distal circlet of spines). S. orapilosus differs from S. barahonensis in the number of segments on the 2 nd minor pereopod (5 in S. orapilosus , 4 in S. barahonensis ).

Figures

FIGURE 14. Synalpheus orapilosus sp. nov. Holotype (A, C–E), male, (USMN 1128427, original VIMS 08CU3102), from an unidentified white webby sponge, Caracas Baai, Curaçao; allotype (B), ov. female, (USNM 1128428, original VIMS 08CU3101), from an unidentified white webby sponge, Caracas Baai, Curaçao. A, carapace, anterior region, and cephalic appendages, dorsal view; B, carapace, anterior region, and cephalic appendages, dorsal view; C, carapace, anterior region, and cephalic appendages, lateral view; D, right third maxilliped; E, left second pereopod. Scale bar = 1.2 mm (A, B); 1 mm (C–E).

FIGURE 15. Synalpheus orapilosus sp. nov. Holotype (A, C–E) male, (USMN 1128427, original VIMS 08CU3102), from an unidentified white webby sponge, Caracas Baai, Curaçao. Allotype (B) ov. female, (USNM 1128428, original VIMS 08CU3101), from an unidentified white webby sponge, Caracas Baai, Curaçao. A, chela of major first pereopod, lateral view; B, chela of major first pereopod, dorsal view; C, merus and carpus of major first pereopod; D, minor first pereopod, dorsal view; E, right third maxilliped, detail of distal end. Scale bar = 1 mm (A–D); 0.3 mm (E).

FIGURE 16. Synalpheus orapilosus sp. nov. Holotype male, (USMN 1128427, original VIMS 08CU3102), from an unidentified white webby sponge, Caracas Baai, Curaçao: A, third pereopod; B, same, detail of distal region; C, fourth pereopod; D, same, detail of distal region; E, fifth pereopod; F, same, detail of distal region. Scale bar = 1 mm (A, C, E); 0.3 mm (B); 0.5 mm (D, F).

FIGURE 17. Synalpheus orapilosus sp. nov. Allotype (A) ov. female, (USNM 1128428, original VIMS 08CU3101), from an unidentified white webby sponge, Caracas Baai, Curaçao. Holotype (B–D) male, (USMN 1128427, original VIMS 08CU3102), from an unidentified white webby sponge, Caracas Baai, Curaçao. A, B, abdomen, lateral view; C, detail of right uropod, dorsal view; D, telson and uropods, dorsal view. Scale bar = 1 mm (A, B, D); 0.5 mm (C).