Pagurellus, Lemaitre & Felder & Poupin, 2017

Lemaitre, Rafael, Felder, Darryl L. & Poupin, Joseph, 2017, Discovery of a new micro-pagurid fauna (Crustacea: Decapoda: Paguridae) in the Lesser Antilles, Caribbean Sea, Zoosystema 39 (2), pp. 151-195 : 165-166

Genus Pagurellus n. gen.

TYPE SPECIES. — Pagurellus jenniferae n. gen., n. sp., by present designation. Gender: masculine.

ETYMOLOGY. — The generic name is derived from the genus name Pagurus , combined with the masculine Latin suffix - ellus which denotes something diminutive, in reference to the minute size of specimens in the single species of this new genus.

DIAGNOSIS. — Nine pairs of biserial phyllobranch gills, no pleurobranchs on somites X, XI (thoracomeres 5 and 6, above pereopods 2 and 3). Rostrum broadly triangular. Crista dentata with accessory tooth. Chelipeds unequal, right largest and stronger than left. Sternite of somite XI (thoracomere 6, pereopod 3) with semi-circular anterior lobe. Pereopod 4 with single row of scales on propodal rasp, dactyl lacking preungual process. Pereopod 5 semi-chelate. Male with paired, unequal, basally weakly calcified, and distally filamentous sexual tubes on coxae of pereopods 5, left tube longer than right, distally coiled; with unpaired, left pleopods 3-5. Female with paired gonopores. Telson nearly symmetrical, with lateral indentations; terminal margins armed with spines.

DISTRIBUTION. — Known based on the type species found in Curaçao. Depth: 224-246.5 m.

REMARKS

This new genus is unique in having the combination of nine pairs of biserial gills, narrowly elongate paired (filament like, often distally semitransparent) tubes on both coxae in the male, no preungual process on pereopod 4, and a cryptic habitat. Of all the pagurid genera in which males have sexual tubes, only five have paired tubes with the left being the largest, as in this new genus. However, the number and type of gills in these five genera vary in number from 9 ( Enneobranchus ) to 11 pairs (all others); the gills are biserial in Anapagurus Henderson, 1886 , and Pumilopagurus , and quadriserial in all others.

Pagurellus n. gen is most similar, at least superficially, to Pumilopagurus McLaughlin & Rahayu, 2008b , in morphology of shield, ocular acicles, ambulatory legs, propodal rasp of pereopod 4, sexual tubes, and telson. However, gill number is different (9 pairs vs 11 pairs in Pumilopagurus ); the right sexual tube in Pagurellus n. gen. is long, and filamentous distally, whereas in Pumilopagurus it is short and stout; the chelipeds in Pagurellus n. gen. are not as strongly unequal, and the right is not as massive, as in Pumilopagurus . Females of Pagurellus have paired gonopores, whereas females of Pumilopagurus have a single left gonopore.

There is an eerie similarity of the chelipeds of the single species of Pagurellus n. gen. with those in species of Anapagrides (e.g., A. reesei [ McLaughlin, 1986]), but otherwise the two genera are markedly different, primarily differing in characters such as gill number (9 pairs vs 11 pairs in Anapagrides ), ocular acicles (bifid vs simple in Anapagrides ), preungual process (absent vs present in Anapagrides ), and male sexual tubes (filamentous, left longest vs stout, right longest in Anapagrides ).