Clibanarius antillensis Stimpson, 1859

Clibanarius antillensis Stimpson, 1859 View in CoL

Megalopa

Size ( Fig. 2A View Figure 2 ). Carapace length = 0.9–1.1 mm; carapace width=0.7‒0.81mm;total length=2.0–2.3mm; n = 96.

Carapace ( Fig. 3A View Figure 3 ). Longer than broad, with few scattered setae; rostrum triangular; ocular peduncles bulbous, reaching half of distal segment of antennular peduncle.

Antennule ( Fig. 3B View Figure 3 ). Biramous. Peduncle 3-segmented; basal segment with 6 simple setae, 1 strong seta at ventrodistal angle; penultimate segment with 3 subterminal setae, 2 simple terminal setae; basal segment with 2 subterminal, 4 short terminal setae. Endopod 3-segmented, with 1, 4, 6 (3 subterminal, 3 terminal) setae, respectively. Exopod with 5 segments, aesthetascs as 0, 6, 5, 3, 0, last segment with 3 subterminal and 1 long terminal setae.

Antenna ( Fig. 3C View Figure 3 ). Basal segment not delineated. Second segment with angular process ending on tip, third segment with 5simple marginal setae.Flagellum with 10 segments, with setae from proximal to distal segment: 0, 3, 4, 5, 4, 5, 5, 6, 5, 9 (6 subterminal and 3 terminal). Exopod reduced, with 5 plumose marginal setae.

Mandible ( Fig. 3D View Figure 3 ). Reduced, simple; palp 2-segmented, 9 marginal serrate setae.

Maxillule ( Fig. 3E View Figure 3 ). Coxal endite with 17 serrate setae. Basal endite with 3 plumose intermediate, 12 cuspidate, 7 serrate setae. Endopod with welldeveloped internal lobe, with 1 simple long terminal seta, external lobe recurved.

Maxilla ( Fig. 3F View Figure 3 ). Coxal endite with 2 plumose subterminal, 4 terminal setae. Basal endite with 10 plumose setae at distal lobe and 5 at proximal lobe. Endopod narrow, significantly twisted, not lobed, without setae. Scaphognathite elongate, proximal free lobe of protopod, with 55 to 60plumose marginal setae.

Maxilliped 1 ( Fig. 3G View Figure 3 ). Coxal endite with 5 cuspidate, 10 plumose submarginal setae. Basal endite with 5 cuspidate, 11 marginal plumose setae. Endopod 1-segmented and narrow. Exopod 1-segmented, with 9 plumose marginal setae.

Maxilliped2 ( Fig.3H View Figure 3 ).Endopod 4-segmented, with 1 or 2, 2, 7, 5 or 6 plumose setae. Exopod 2-segmented, 8 or 9 plumose terminal setae, 1 or 2 plumose setae on inner margin.

Maxilliped 3 ( Fig.3I View Figure 3 ).Endopod 5-segmented; crista dentata on proximal segment with 4 to 6 denticles, 2 subterminal, 5 simple terminal setae, second segment with 2 simple subterminal setae, 2 simple terminal setae, third segment with 11 subterminal setae, 5 terminal setae, 5 marginal setae, fourth segment with 13 plumose setae and fifth segment with 7 plumose setae. Exopod 2-segmented, with 1 simple marginal seta, 8 plumose terminal setae.

First pereiopod (chelipeds) ( Fig. 3J View Figure 3 ). Chelae equal, with segments smooth; coxa with 3 simple setae; basis with 6 simple setae; ischium with 5 simple setae; merus, longest segment, with 8 simple setae; carpus with 6 simple setae; propodus with 16 simple setae, distal upper extremity corneous; dactyl length about half palm including the propodal prolongation, with 16 simple setae and distal extremity corneous.

Second pereiopod ( Fig. 3K View Figure 3 ). Coxa with 2 simple setae; basis smaller with 3 simple setae; ischium with 4 simple setae; merus, longest segment, with 9 simple setae; carpus less than half the ischium length, with 5 simple setae; propodus longer than carpus, with 15 simple setae and; dactylus very stout, apically curved with corneous tip, with 11 simple setae and 3 spines.

Third pereiopod ( Fig. 3L View Figure 3 ). Coxa with 3 simple setae; basis with 3 simple setae; ischium with 11 simple setae; merus longer than ischium and with 10 simple setae; carpus with 5 simple setae; propodus longer than carpus, with 14 simple setae and 3 stout cuspidate seta; dactylus very stout, apically curved and corneous, with 16 simple setae and 4 spines.

Fourth pereiopod ( Fig. 3M View Figure 3 ). Coxa with 2 simple setae; basis with 4 simple setae; ischium with 4 simple setae; merus with 6 simple setae; carpus with 5 simple setae; propodus, with 5 simple setae and 17 pseudochaetae scales forming protopodal plate; dactyl with 1 long papposerrate seta, 7–9 simple setae and 3 teeth on distal extremity.

Fifth pereiopod ( Fig. 3N View Figure 3 ). Coxa with 4 simple setae; basis with 4 simple setae; ischium with 3 simple setae; merus with 6 simple setae; carpus with 5 simple setae; propodus, with 6–7 long papposerrate, 10–11 simple setae and 23 pseudochaetae scales; dactyl with 7 simple setae, 1 long papposerrate distal and 5 pseudochaetae scales.

Pleon ( Fig. 3A View Figure 3 ). Pleonites 2–5 with rounded posterolateral angles, lateral margins with 3 simple short setae; pleonite 6 with 4 simple setae at posterior dorsal margin and 2 simple setae at posterolateral angles.

Pleopods ( Figs. 3O–R View Figure 3 ). Pleopod developed on pleonites 2–5, decreasing in size distally. Endopod unsegmented, with pair of hooks at apical margin. Exopods 2-segmented with 9 plumose setae.

Uropods ( Fig. 3S View Figure 3 ). Segment protopodal with 0–3 simple setae. Endopod with 1 or 2 simple setae on dorsal surface, 11–14 plumose marginal setae and 5–7 corneal scales; Exopods with 0–4 short plumose setae on dorsal surface, 19–21 plumose marginal setae and 8–12 corneous scales.

Telson ( Fig. 3S View Figure 3 ). Shape rounded posterior margin, with 9 posterior plumose marginal setae, 2 pairs of submarginal short plumose setae, 4 pairs of short simple setae on dorsal surface.

Remarks. We found four meristic differences among the Brazilian ( Brossi-Garcia and Hebling, 1983) the Panamanian ( Siddiqui et al., 1991) and Mexican populations ( Tab.1). The antennule in the Panamanian and Mexican populations had more aesthetascs on the second, third and fourth segments (0. 6, 5, 3, 0) with respect to the Brazilian population (0, 4, 4, 2, 0). There were fewer plumose setae on the scaphognathite in the Panamanian and Mexican populations (49–55) with respect to the Brazilian population (70 plumose setae). In the second maxilliped, the difference was of 1 seta, whereas in maxilliped 3, there were 1–3 fewer denticles in the Brazilian population on the crista dentata. The exopod of the uropod had fewer (10) marginal plumose setae in the Brazilian population.