Nematopaguroides pusillus Forest

Lemaitre, Rafael & Tavares, Marcos, 2015, New taxonomic and distributional information on hermit crabs (Crustacea: Anomura: Paguroidea) from the Gulf of Mexico, Caribbean Sea, and Atlantic coast of South America, Zootaxa 3994 (4), pp. 451-506 : 489-492

Nematopaguroides pusillus Forest & de Saint Laurent, 1968

( Figs. 19 , 20 )

Nematopaguroides ? pusillus Forest & de Saint Laurent, 1968: 159, figs 142–146 (type locality: off Pernambuco, Brazil, Calypso , sta 23, 8°19.5’S, 34°39’W).

Nematopaguroides pusillus . — Coelho & Ramos, 1973: 166.— Coelho & Santos, 1980: 143.—Reed et al., 1982: 768.—Reed et al., 1982: 768.— Abele & Kim, 1986: 386, figs i–k.—Coelho & Ramos-Porto, 1987: 43.— Rieger, 1998: 417.— Melo, 1999: 118, figs 63, 64.— Wang & McLaughlin, 2000: 956.— Coelho et al., 2007: 10, tab. 4.— McLaughlin et al., 2010: 31.

New material. Southeastern Florida. R/V Johnson, Jeff’s Reef, 27°32.8’N, 79°58.8’W, in Oculina reef samples, Cr. 27, JSL-II, dive 129a, 77.7 m, 23 Sep 1976: 2 males 1.3–1.5 mm, 1 female 1.2 mm, 1 ov female 1.1 mm ( HBOI 089:06387); Cr. 42, JSL-II, dive 184a, 80.2 m, 15 Apr 1977: 2 males 1.1, 1.3 mm, 1 female 0.8 mm, 1 ov female 1.3 mm ( HBOI 089:06385); Cr. 47, JSL-II, dive 438b, 81.4 m, 23 Aug 1977: 4 sex indet. (dismembered) 0.7–0.8 mm ( HBOI 089:06386).

Brazil. Espírito Santo, TAAF MD55, sta 23 DC 40, 20°39.8’S, 34°41.1’W, 60 m, 17 May 1987: 1 male 1.4 mm ( MZUSP 16832).

Diagnosis. (See also Forest & de Saint Laurent 1968). Shield ( Fig. 19 A) about as long as broad, naked or with scattered short setae; lateral projections terminating in minute spine; rostrum broadly triangular, rounded. Ocular peduncles slightly constricted medially, with scattered setae dorsally; cornea weakly dilated; acicles subtriangular, each terminating in simple terminal spine or rarely 2 small spines. Antennular peduncles exceeding distal margin of cornea by half length of ultimate segment, naked. Antennal peduncle exceeding distal margin of cornea by onefourth length of fifth segment; second segment with distolateral angle produced and terminating strong spine; antennal acicle reaching to proximal margn of cornea, terminating in sharp spine, unarmed except for tuft of setae on mesial margin and long setae distally; flagellum with scattered short setae ≤ 1 article in length. Chelipeds ( Fig. 19 B, C) markedly dissimilar, stout. Right cheliped sparsely setose; fingers distinctly shorter than palm, cutting edges each with 3 (dactyl) or 1 (fixed finger) large calcareous teeth; chela with row of small spines on dorsomesial and dorsolateral margins; carpus with dorsomesial row of small spines and scattered small spines on dorsal surface. Left cheliped with scattered, moderately long setae on merus, carpus, and chela; fingers twice as long as palm; chela with dorsolateral margin elevated and armed with row of sharp, mostly forwardly curving spines; carpus with a few dorsomedial spines; carpus with strong dorsodistal spine. Ambulatory legs ( Fig. 20 A, B) each with dactyl slightly longer than propodus, with ventromesial row of 6–8 long, slender spinules; meri, carpi and propodi with long setae or tufts of setae on dorsal margins; segments unarmed except for small, blunt dorsodistal spine on carpi. Fourth pereopod ( Fig. 20 C) semichelate, propodal rasp consisting of single row of ovate scales; lacking preungual process. Anterior lobe of sternite XII ( Fig. 19 E) subsemicircular. Uropods markedly asymmetrical. Telson ( Fig. 20 D) with prominent median cleft separating slightly asymmetrical posterior lobes; rounded terminal margins of posterior lobes each with row of 4 or 5 spines of similar size. Male with coxae of fifth pereopods symmetrical, each coxa with long, slender, and distally filamentous sexual tube ( Fig. 19 E) directed obliquely outward. Female with paired gonopores.

Distribution. Western Atlantic: known only from off southeastern Florida, and Brazil (Espírito Santo). Depth: 60 to 81.4 m.

Remarks. This rarely collected species was previously known only from the type material used by Forest & de Saint Laurent (1968) from off Pernambuco, Brazil, and specimens collected off southeastern Florida as part of an Oculina deep reef ecology study by Reed et al. (1982). In the latter study, however, only the number of specimens collected was reported, without including any taxonomic or morphological details. Various listings from Florida ( Abele & Kim 1986) and Brazil ( Coelho & Santos 1980; Coelho & Ramos-Porto 1987; Rieger 1998; Melo 1999; Coelho et al. 2007) have also included this species without reporting any new material. The discovery of an additional specimen of N. pusillus from the coast of Espírito Santo, Brazil, confirms the presence of this rare species along that portion of the southwestern Atlantic, while still leaving a large gap in its distribution between Bahia and Florida.

At the time Forest & de Saint Laurent (1968) described N. pusillus , they questionably placed it in Nematopaguroides because the only male known had paired sexual tubes, whereas males of the only other known species and type of the genus, N. fagei Forest & de Saint Laurent, 1968, had unpaired right sexual tube. When Wang & McLaughlin (2000) made the remarkable discovery of a third species of Nematopaguroides , N. reconditus Wang & McLaughlin, 2000 , in the South China Sea, with males having a long sexual tube on the right side and a short sexual tube on the left side, they concluded that a left sexual tube could be present as well in species of Nematopaguroides , and thus concluded that both N. reconditus and N. pusillus could correctly belong in this genus.

Individuals of Nematopaguroides pusillus are minute in size, ranging in shield length 0.7–1.5 mm. The rareness of collections of this species may be attributed, in part, to the small size as well as the cryptic habitat, such as the dense Oculina coral reefs off the coast of eastern Florida, where it has been found.

Figures

FIGURE 19. Nematopaguroides pusillus Forest & de Saint Laurent, 1968: male 1.4 mm, Brazil, TAAF MD 55, sta DC 40 (MZUSP 16832). A, shield and cephalic appendages, dorsal; B, right cheliped, dorsal; C, left cheliped, dorsal; D, same, lateral; E, sternum, coxae of pereopods, and sexual tubes, ventral. Scale: 0.5 mm.

FIGURE 20. Nematopaguroides pusillus Forest & de Saint Laurent, 1968, male 1.4 mm, Brazil, TAAF MD 55, sta DC 40 (MZUSP 16832): A, right second pereopod, lateral; B, right third pereopod, lateral; C, propodus and dactyl of right fourth pereopod, lateral; D, telson, dorsal. Scale: 0.5 mm.