Trichopagurus

Komai, Tomoyuki & Osawa, Masayuki, 2005, Decapoda: Anomura: Paguridae) from the Ryukyu and Yap Islands, and redescription of T. trichophthalmus (Forest), Zootaxa 801, pp. 1-20 : 2-3

Trichopagurus de Saint Laurent, 1968

Trichopagurus de Saint Laurent, 1968: 927; 1970: 210; McLaughlin, 2003a: 128.

Type species. Catapaguroides ? trichophthalmus Forest, 1954 . Gender: Masculine.

Emended diagnosis. Gills biserial, 11 pairs, including 1 pleurobranch above third pereopod (sixth thoracic somite) and 2 arthrobranchs on each third maxilliped to fourth pereopods; most lamellae distinctly narrowed distally. Rostrum distinct, triangular. Ocular acicles simple. Third maxilliped with 1 accessory tooth. Chelipeds strongly unequal, with weak degree of sexual dimorphism. Fourth pereopod semichelate, propodal rasp consisting of 1 row of corneous scales; no preungual process. Coxa of male right fifth pereopod with moderately long sexual tube directed toward exterior, distal part of tube semitransparent, coiled; left with very short tube. Female with single left gonopore; coxae of fifth pereopods slightly to somewhat asymmetrical, left largest. Anterior lobe of sixth thoracic somite transversely oblong. Eighth thoracic sternite composed of 2 distinct, rounded lobes. Male with unpaired left third to fifth pleopods; female with unpaired left second to fifth pleopods, no paired first pleopods modified as gonopods. Uropods markedly asymmetrical. Telson with faint or distinct transverse indentations, terminal margins oblique; posterior lobes each with fringe of long setae on lateral margin.

Remarks. As noted before, the gills of Trichopagurus trichophthalmus have been reported as ‘intermediaire’ (de Saint Laurent 1968, 1970) or quadriserial ( McLaughlin 2003a). De Saint Laurent (1970) illustrated a shallowly divided gill lamella. However, our examination of the holotype and additional specimens has shown that the gill lamellae of T. trichophthalmus are actually entire, lacking distal division. Most gill lamellae, however, are abruptly narrowed distally, and the partially overlapping distal parts of a few gill lamellae might give the incorrect impression that each lamella is divided distally.

It is worth comparing Trichopagurus with Anapagrides de Saint Laurent­Dechancé, 1966 and Catapagurus A. Milne­Edwards, 1880 (rediagnosed by McLaughlin 2004), as all are characterized by 11 pairs of biserial gills, strongly unequal chelipeds, single row of scales in the propodal rasp on the fourth pereopod, and some development of a right sexual tube of male. Anapagrides primarily differs from Trichopagurus in the structure of the right sexual tube. In Anapagrides , the right sexual tube is short (about 0.5–1.2 times the length of the coxa of the fifth pereopod) and is posteriorly directed. Catapagurus is easily distinguished from Trichopagurus by the broadly rounded rostral lobe, the possession of a ventral row of very small spinules on the ambulatory dactyli, instead of rather strong corneous spines, and the presence of paired female gonopores. In addition, Catapagurus species occasionally have elongate ocular acicles and usually a well developed preungual process on the dactylus of the fourth pereopod.