Nematopagurus micheleae, Lima & Tavares & Jr, 2019

Lima, Daniel, Tavares, Marcos & Jr, Joel Braga De Mendonça, 2019, Paguroids (Decapoda: Anomura: Diogenidae and Paguridae) of the remote oceanic Archipelago Trindade and Martin Vaz, off southeast Brazil, with new records, description of three new species and zoogeographical notes, Zootaxa 4694 (1), pp. 1-63 : 31-37

Nematopagurus micheleae sp. nov.

( Figs. 15–18 )

Trindade specimens. HOLOTYPE: male sl 1.1 mm ( MZUSP 36321 ), Brazil, Espirito Santo, Trindade Island, Enseada dos Portugueses, stn Farol , 20°29’52.3”S, 29°19’15.6”W, J.B. Mendonça coll., 08.vii.2015, artificial reef substrate, 15 m. PARATYPE: 1 male sl 0.9 mm ( MZUSP 36197 ), same collection data as for holotype .

Type locality. Enseada dos Portugueses, 20°29’52.3”S, 29°19’15.6”W, 15 m, Trindade Island , off Espirito Santo, Brazil.

Distribution. So far know only from Trindade Island, 15 m.

Etymology. The specific name is in honor of the late Michèle de Saint Laurent (1926–2003) for her outstanding work on the taxonomy of decapod crustaceans, with special reference to hermit crabs.

Description. Eleven pairs of bisserial gills. Shield ( Fig. 15A ) 1.1 times as long as broad; dorsal surface smooth, except by few tufts of short setae on linea-d. Anterolateral margin sloping. Anterior margin between rostrum and lateral projections distinctly interrupted. Posterior margin truncate. Rostrum obtusely rounded, produced to level of lateral projections. Lateral projections rounded.

Ocular peduncle ( Fig. 15A ) short, stout, 0.5 times length of shield; basal portion laterally inflated, narrowing to distal margin; mesial surface almost straight; corneal diameter 0.6 of peduncular length, markedly reduced than basal portion of peduncle; mesial surface with scattered short setae; tuft of long setae overreaching dorsodistal corneal margin. Ocular acicles each with slender, long projection, reaching by 0.5 times to entire length of ocular peduncles, separated by about basal width of 1 acicle.

Antennular peduncle ( Fig. 15A ) long, overreaching distal margin of fifth segment of antennal peduncle. Ultimate segment with tufts of very long, plumose setae on dorsodistal margin reaching distal margin of antennular flagellum; dorsal surface with scatteredshort setae. Penultimate and basal segments glabrous. Basal segment with spine on statosyst lobe.

Antennal peduncle ( Fig. 15A ) long, overreaching distal corneal margin by total length of fifth segment. Fifth segment with both, scattered short to moderately long setae on dorsal and ventral surfaces. Fourth segment with tuft of short setae on ventrodistal margin. Third segment with small spine and tuft of short setae on ventrodistal margin. Second segment with dorsolateral angle produced, terminating in bifid spine; mesial margin with few short setae; lateral margin with both few short to moderately long setae; dorsomesial angle with a small spine. First segment with small spine on ventrodistal margin.Antennal acicle long, overreaching distal corneal margin, reaching to proximal one-thirds of fifth antennal segment; curved outward, terminating in small spine; mesial margin with row of long setae and tuft of long stiff setae distally. Antennal flagellum long, overreaching tip of extended right cheliped; each article with 4–5 small setae, 1 or 2 articles in length.

Mouthparts not dissected. Ischium with strong accessory tooth on well-developed crista dentata (14–15 corneous teeth).

Chelipeds subequal, right ( Fig. 16 A–C) stronger and longer than left. Right cheliped dactylus 0.7 times as long as palm; mesial margin with row of tubercles and row of moderately long setae; ventral surface with scattered short setae; cutting edge with row of calcareous teeth proximally and row of minute corneous teeth distally, terminating in small corneous claw. Fixed finger cutting edge with small calcareous teeth and prominent tooth about midlength of finger; dorsal surface with tufts of short setae and scattered short to moderately long setae. Palm semi-ovate, 0.8 times as long as carpus; dorsolateral margin with row of blunt spines, extending onto two-thirds of fixed finger; dorsal surface with scattered short to moderately long setae, with irregular median rows of minute spines proximally; mesial margin with row of small tubercles and scattered moderately long setae; dorsomesial margin rounded, not clearly delimited.Carpus as longer as merus; row of small tubercles delimiting dorsolateral margin preceded by strong distal spine; dorsomesial margin with 1 distinct distal tubercle; mesial surface with minute distal spine and scattered short to moderately long setae; ventromesial margin with row of moderately long setae. Merus unarmed, except by small spine on ventromesial margin, with row of moderately long setae; dorsodistal margin with tuft of moderately long setae; ventrolateral margin with spiny tubercles of different sizes distally. Ischium with scattered short setae on dorsal and ventral surfaces.

Left cheliped slender ( Fig. 17 A–C). Dactylus 1.2 times as long as palm; dorsal surface rounded with scattered short setae; cutting edge with row of small corneous teeth, interspersed with small calcareous teeth distally. Fixed finger cutting edge with minute corneous teeth on distal half, terminating in small corneous claw. Palm 0.5 times as long as carpus; slightly inflated ventrally; dorsal surface markedly elevated medially, with row of small spines, not reaching to basal part of fixed finger; dorsolateral and dorsomesial margins delimited by longitudinal rows of tubercles. Carpus elongated, longer than merus, triangular; 2 strong dorsodistal spines, scattered tufts of long stiff setae dorsally; ventrolateral distal angle with small spine. Merus elongated, subtriangular, tufts of long stiff setae on dorsodistal margin; ventrolateral margin with 2 prominent spines subdistally; ventromesial margin serrated. Ischium with scattered short setae.

P2 and P3 ( Fig. 18 A–C) similar from left to right, third longer than second. Dactyli 1.2 times as long as propodi; dorsal surface with row of moderately long setae; ventromesial margin with row of 5–8 corneous spines, increasing in size distally; mesial, lateral and ventral margins with row of scattered short setae, terminating in corneous claw, triangular, curved. P2 with propodus slender and longer than P3; propodi 1.1–1.5 times as long as carpi; ventrodistal angle with 1 spinule; ventral margin with row of few, spaced, short setae; dorsal surface with row of long setae. Carpi with 0.6–0.8 times as long as meri; dorsodistal margin without spine; dorsal surface with row of long setae; lateral and mesial surfaces with few moderately long setae dorsally; ventral margin with scattered short setae. Meri unarmed, with row of moderately long setae on dorsal surface, and scattered short to moderately long setae on ventral margin; dorsodistal margin with tuft of moderately long setae. Isquia unarmed; P3 ischium very long, with 0.7 times as long as merus, with row of long setae on ventral margin; P2 ischium 0.3 times as long as merus, with scattered short setae on ventral and dorsal margins. Anterior lobe of third sternite rounded or rounded rectangular, with long setae on anterior margin ( Fig. 15B ).

P4 semichelate ( Fig. 17D ). Dactylus long, curved distally, with row of minute corneous teeth, increasing in size distally; dorsodistal margin with tuft of moderately long and long setae on dorsal surface. Propodus with tuft of long setae on dorsodistal margin; propodal rasp consisting of single row of 12 ovate corneous scales.

P5 chelate. Propodal rasp dorsally extending for about half surface of propodus.

Adult males with right sexual tube ( Fig. 15C ) very long, distally filamentous, orientated from right to left across ventral body. Left sexual tube very short; unpaired Pl3–Pl5, each with exopodite longer than endopodite. Uropods asymmetrical. Telson ( Fig. 15D, E ) with markedly (holotype) or weak (paratype) lateral indentation; posterior lobes without spinose projection on terminal margins typical to Nematopagurus ; terminal margins rounded, with shallow median cleft; posterior lobe with scattered long setae on terminal margin and few spinules medially on both sides, short setae on dorsal margin; anterior lobe with scattered short to moderately long setae on lateral margins.

Remarks. Nematopagurus was erected by A. Milne-Edwards & Bouvier (1892) for a single eastern Atlantic species, N. longicornis A. Milne-Edwards & Bouvier, 1892 , currently known from Ireland to Angola, and the Mediterranean Sea ( McLaughlin 2004). No other species in the genus is known from the Atlantic Ocean to date, while 25 additional species have been reported from the Pacific Ocean, as far east as Hawaii and French Polynesia.

Nematopagurus micheleae sp. nov. is hence the second Atlantic species of Nematopagurus , and the first representative of the genus from the western Atlantic. The new species is confidently assigned to Nematopagurus (sensu McLaughlin, 2004) on the account of its long, distally filamentous male right sexual tube, directed from the right to the left across the ventral body surface, and very short left sexual tube, readily recognized in the holotype and paratype males.

Nematopagurus micheleae sp. nov. can be immediatelly separated from all its congeners in having the terminal margin of the posterior lobe of the telson inermis ( Fig. 14E ), whereas in all other Nematopagurus the terminal margins of the telson is distinctly spinose.

The new species can be further differentiated from the eastern Atlantic N. longicornis in having (1) the ocular peduncle swollen basally, tapering distally to a reduced cornea, Fig. 15A (vs. ocular peduncle broadening distally to a dilated cornea in N. longicornis ); (2) the P2 and P3 dactili ventral margins each with 5–8 corneous spines, Fig. 18 A–C (vs. P2 and P3 dactli ventral margins each with 12–18 corneous spines); and (3) the length of the P3 dactylus 6.4 its height, Fig. 18B (vs. length of the P3 dactylus 13.4 its height in N. longicornis ).

Nematopagurus sp. nov. and N. helleri ( Balss, 1916) from the Red Sea are superficially similar to each other in that their ocular peduncle is swollen basally, tapering distally to a reduced cornea, but can be further separated by the P2 and P3 carpi dorsal surface inermis, Fig. 18 A–C (vs. P2 and P3 carpi each with a dorsodistal spine. Additionally, P2 carpus with 2–4 widely-spaced spines on its dorsal surface and P3 carpus usually with 1–2 spines on its proximal third in N. helleri ) (see McLauglin 2004: 187, 188, fig. 13C).

Differently from the remaining Nematopagurus species, known from waters between 100–2600 m, the new species is a shallow-water one (15 m).

Figures

FIGURE 14. (A) Iridopagurus martinvaz sp. nov., male paratype, sl 0.8 mm (MZUSP 38196). (B) Iridopagurus reticulatus (García-Gómez, 1983) from Saint Martin Island. Photographs by J.B. Mendonça Jr. (A) and J. Poupin and L. Corbari (B).

FIGURE 15. (A–F) Nematopagurus micheleae sp. nov. (A–D) male holotype, sl 0.9 mm (MZUSP 36197). (E, F) male paratype, sl 1.1 mm (MZUSP 36321). (A) shield and cephalic appendages. (B) sternite XII and coxae of P3, ventral view. (C) sternite XIV and coxae of P5 with the sexual tubes, ventral view. (D, E) sixth pleonal somite and telson, dorsal view. (F) posterior margin of telson, dorsal view. Note the spines at the median cleft, omitted in (D, E). Scale bars: A, C–E, 0.5 mm; B, F, 0.25 mm.

FIGURE 16. (A–C) Nematopagurus micheleae sp. nov., male holotype, sl 0.9 mm (setae partially omitted) (MZUSP 36197). (A) right cheliped chela and carpus, dorsal view. (B) right cheliped, mesial view. (C) right cheliped, lateral view. Scale bars: 1.0 mm.

FIGURE 17. (A–D) Nematopagurus micheleae sp. nov., male holotype, sl 0.9 mm (setae partially omitted) (MZUSP 36197). (A) left cheliped, dorsal view. (B) left cheliped, mesial view. (C) left cheliped, lateral view. (D) dactylus, propodus and carpus of left P4, lateral view. Scale bars: A–C, 0.5 mm; D, 0.25 mm.

FIGURE 18. (A–C) Nematopagurus micheleae sp. nov., male holotype, sl 0.9 mm (MZUSP 36197). (A) left P2, mesial view. (B) left P3, lateral view. (C) left P2, lateral view. Scale bar: 1.0 mm.