Synalpheus plumosetosus, Iii, Kenneth S Macdonald, Hultgren, Kristin & Duffy, Emmett, 2009
Iii, Kenneth S Macdonald, Hultgren, Kristin & Duffy, Emmett, 2009, The sponge-dwelling snapping shrimps (Crustacea, Decapoda, Alpheidae, Synalpheus) of Discovery Bay, Jamaica, with descriptions of four new species, Zootaxa 2199, pp. 1-57: 36-42
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Synalpheus plumosetosus , n. sp.
Material examined. Jamaica: Holotype: non-ovigerous individual, CL: 2.55 mm, ( USNM 1126369, original VIMS 08JAM 2706), Dairy Bull Reef, (18 ° 28.083 ΄ N, 77 ° 23.289 ΄ W), from canals of Auletta cf. sycinularia . Allotype: ovigerous female, CL: 2.62 mm, ( USNM 1126370, original VIMS 08JAM 2704), Dairy Bull Reef, from canals same of same individual Auletta cf. sycinularia as holotype. Paratypes: non-ovigerous individual, CL: 2.59 mm, ovigerous female, CL: 2.47 mm, ( USNM 1126371,1126372, original VIMS 08JAM2705,07), Dairy Bull Reef, from canals same of same individual Auletta cf. sycinularia as holotype. MaxCL ovigerous female: 2.62 mm. MaxCL non-ovigerous individual: 2.55 mm.
Description. Body form subcylindrical; carapace smooth, sparsely setose, posterior margin with cardiac notch distinct. Rostrum longer than ocular hood ( Fig. 17 View FIGURE 17 , 18 View FIGURE 18 ), distinctly narrower, distally upturned; margins in dorsal view, slightly concave. Ocular hoods dorsally convex; in dorsal view, blunt, separated from rostrum by deep adrostral sinus. Stylocerite acute, with blunt tip; mesial margin concave; reaching beyond midpoint of first segment of antennular peduncle. First antennular segment without ventromesial tooth, and with two basal ventral processes. Basicerite without tooth on dorsomesial corner, with longer ventrolateral spine, reaching distal end of third segment of antennular peduncle. Scaphocerite without blade, acute lateral spine robust, with lateral margin slightly concave, slightly shorter than basicerite spine, reaching almost to distal end of third segment of antennular peduncle. Third maxilliped with distal circlet of approximately six spines on distal segment, without ventrodistal spine on antepenultimate segment.
Major first pereopod ( Fig. 17 View FIGURE 17 , 18 View FIGURE 18 ) massive, fingers clearly shorter than half length of palm; fixed finger slightly shorter than dactyl. Palm of chela with tapering acute distal protuberance on superior margin, directed slightly downward, towards dactyl. Minor first pereopod ( Fig. 19 View FIGURE 19 ) with palm clearly less than two times longer than high; fingers clearly shorter than palm; dactyl with flexor margin concave, blade-like, with small but distinct second tooth basal to strongly curved tip; extensor surface of dactyl with thick brush of curved, plumose setae; fixed finger with flexor margin straight, blade-like, and small but distinct second tooth basal to strongly curved tip.
Second pereopod ( Fig. 20 View FIGURE 20 ) with carpus 5 -segmented, subequal in length to merus. Both fingers terminating in a narrow, curved tooth.
Third pereopod ( Fig. 20 View FIGURE 20 ) slender; dactyl biunguiculate, with flexor unguis subequal in thickness to extensor, mesial margin of flexor unguis strongly convex; propodus with row of six movable spines on flexor margin and one pair of distal movable spines flanking base of dactyl; carpus with distal movable spine on flexor margin; merus 3 ½ times longer than wide, without movable spines on flexor margin. Fourth pereopod ( Fig. 20 View FIGURE 20 ) similar to third, weaker, propodus with five spines on flexor margin. Fifth pereopod ( Fig. 20 View FIGURE 20 ) weaker than fourth; propodus with only four spines on flexor margin, and four transverse combs of stout setae on ventral face; carpus without distal spine.
First pleura ( Fig. 17 View FIGURE 17 ) of male with posterior corner distinctly produced ventrally into short, blunt, downward directed point; second pleura of male broadly rounded. Third to fifth pleura of male with straight ventral margin, rounded anterior corner and subacute posterior corner.
First pleopod ( Fig. 21 View FIGURE 21 ) of male with 2 terminal setae on endopod; second pleopod of male with marginal setae on exopod originating in distal one-half; appendix interna present on second to fifth male pleopods. Second pleopod ( Fig. 21 View FIGURE 21 ) of female with marginal setae on exopod originating in distal one-half; appendix interna present on second to fifth female pleopods.
Telson ( Fig. 17 View FIGURE 17 , 18 View FIGURE 18 ) with convex lobe on distal margin; posterior corners adjacent to spines obtuse. Space between distal spines 25 % of distal margin, lateral spines ~ 70 % length of mesial. Distal margin ~ 30 % width of proximal margin. Uropods ( Fig. 17 View FIGURE 17 ) with a single fixed tooth on lateral margin of exopod distinctly removed anteriorly from the movable spine, the latter longer and thicker than adjacent posterior fixed tooth.
Colot in life. Nondescript, translucent with dull gold tinge to thickened parts of cuticle; distal palm and fingers of major chela orange; ovaries and embryos drab green.
Etymology. We have named this species for its distinguishing characteristic: the plumose setae making up the setal brush on the minor chela.
Variation. There is variation in the relative lengths of the scaphocerite and basicerite among the four specimens examined. In the holotype and allotype ( USNM 1126369,70), the scaphocerite is longer than the basicerite, while in the two paratypes ( USNM 1126371,72), the scaphocerite is shorter.
Hosts and ecology. All four individuals were collected from the canals of Auletta cf. sycinularia (Plate 7 B). This sponge appears to be the same species from which all samples of Synalpheus irie , n. sp. were also collected.
Distribution. Jamaica (this study).
Remarks. Synalpheus plumosetosus n. sp. appears to be another member of the complex of morphologically similar species that includes S. brooksi , S. bousfieldi , S. chacei , S. corallinus n. sp. and S. thele n. sp. (see Table 3). Synalpheus plumosetosus can be easily distinguished from all of these by the setal brush on the dactyl of its minor chela, which consists of plumose setae rather than the simple setae found in all other examined Synalpheus species. In most other characters, S. plumosetosus resembles S. bousfieldi .
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