Pasiphaea mclaughlinae, Hayashi, 2006

Hayashi, Ken-Ichi, 2006, A new species of the Pasiphaea sivado species group from Taiwan (Decapoda, Caridea, Pasiphaeidae), Zoosystema 28 (2), pp. 341-346 : 342-346

Pasiphaea mclaughlinae n. sp.

( Figs 1-3 )

TYPE MATERIAL. — Holotype: SE coast of Taiwan , Ocean Researcher 1, TAIWAN 2001, stn CP 126, 22°13.8’N, 121°01.8’E, 1222-1226 m, 21.VIII.2001, 1 ♂ cl 16.1 mm (MNHN-Na 16064).

Paratype:South China Sea, Ocean Researcher 1, TAIWAN 2001, stn CP 131, 22°17.3’N, 120°05.5’E, 732-839 m, 22.VIII.2001, 1 ♂ cl 16.0 mm (MNHN-Na 16065).

ETYMOLOGY. — With pleasure I dedicate this new species to Patsy McLaughlin, in recognition for her outstanding contributions to carcinology.

DISTRIBUTION. — Known only from the localities of the type material, on the southern part of Taiwan ; depths: 732-839 and 1222-1226 m.

DIAGNOSIS. — Small species. Exoskeleton hard, not fragile. Rostrum spine-like, moderately large. Carapace dorsally rounded; branchiostegal sinus obliquely shallow; branchiostegal spine marginal. First abdominal somite dorsally rounded, second to fifth somites flat dorsally, sixth somite rounded at anterior three-fourths and flat at posterior one-fourth, with distinct posteromedian spine.Telson shallowly grooved dorsally; posterior margin truncate, with three pairs of spines. First pereopod with four to six spines on merus; basis with long, sharply produced tooth at posterodistal angle; fingers shorter than palm; palm with two isolated setae. Second pereopod with five to seven spines on merus; ischium and basis unarmed except for long, sharply produced tooth at posterodistal angle of basis. Four pleurobranchiae and three arthrobranchiae.

DESCRIPTION

Size small (known specimens cl 16.0, 16.1 mm). Rostrum ( Fig. 1A ) spine-like, moderately large, posterodorsal margin slightly convex, anterior margin weakly concave ( Fig. 2A, C ); apex just reaching or slightly falling short of anterodorsal margin of carapace ( Figs 1A ; 2 A-C). Carapace dorsally rounded, anterodorsal part thin, short, directed downward in lateral view, anterolateral margin obliquely sinuous in lateral view ( Fig. 2C ). Branchiostegal spine comparatively large, marginal or submarginal, branchiostegal sinus shallow, long ( Fig. 2A, C ).

First abdominal somite dorsally rounded, second to fifth somites dorsally flat ( Fig. 1B ), sixth somite 1.7 times as long as fifth somite, dorsally rounded at anterior three-fourths, flat at posterior onefourth, with strong posteromedian spine, extending directed posteriorly ( Fig. 2D ). Telson 0.7 times as long as sixth somite, dorsally grooved throughout ( Fig. 2E ), posterior margin truncate, with three or four pairs of spines ( Fig. 2E, F ). Eyes well developed, cornea semispherical attached obliquely on eyestalk in dorsal view ( Fig. 2B ). Stylocerite falling short of distal margin of first segment of antennular peduncle ( Fig. 2A ). Antennal scale about four times as long as wide ( Fig. 2G ), shorter than chela of first pereopod; basicerite with slender spine on ventrodistal corner ( Fig. 2A, G ). Mouthparts typical of genus ( Fig. 3 A-F); third maxilliped reaching slightly beyond antennal scale ( Fig. 3F ).

First pereopod reaching beyond swollen part of antennular flagellum by length of fingers ( Fig. 3G ); palm with two slender setae on mesial surface near ventral margin, distal one near base of dactylar articulation, proximal one at mid-length of palm ( Fig. 2H ); fingers 0.7 times as long as palm; merus with four to six spines on nearly entire posterior margin ( Fig. 3G ); ischium unarmed, anterodistal part slightly broadened; basis with acute tooth on posterodistal corner, anterior margin weakly convex ( Fig. 2I ). Second pereopod reaching beyond swollen part of antennular flagellum by length of fingers ( Fig. 3H ), chela of second pereopod slender and long, about 1.2 times as long as first chela; no setae on palm; fingers as long as palm; merus with five to seven spines on posterior margin ( Fig. 3H ); ischium unarmed, anterodistal part slightly broadened; basis with acute tooth on posterodistal corner ( Fig. 2J ), tooth on first pereopod more erect than that on second pereopod, anterior margin strongly convex. Posterior three pereopods typical of genus ( Fig. 3 I-K). Third pereopod reaching distal margin of first segment of antennular peduncle. Fourth pereopod short, not reaching basal tooth on second pereopod. Fifth pereopod reaching distal margin of cornea. Endopod of male first pleopod and appendix interna and appendix masculina without distinguishing characters ( Fig. 3L, M ).

Pleurobranchiae present on fourth to seventh thoracic somites, arthrobranchiae present on fourth to sixth somites; eighth somite without gill. All gills composed of developed lamellae. First to fifth pereopods with well developed exopods, but without epipods or podobranchiae ( Fig. 2K ).

REMARKS

The subgroup to which P.mclaughlinae n. sp. belongs is also characterized by the following features: the size of individuals is small, cl less than 15 mm in males and ovigerous females, the rounded dorsal margin of the carapace, the posteromedian spine on the sixth abdominal somite, two setae on the palm of the first pereopod, and a strong tooth on posterodistal corners of the basis of the first and second pereopods. As previously mentioned, this subgroup now includes P. debitusae , P.fragilis , P.gracilis , P. laevis , P. marisrubri , and P.philippinensis , to which P. mclaughlinae n. sp. is now added. Of these P. marisrubri and P. philippinensis bear two to seven spines on the posterior margin of the basis of the second pereopod; P. debitusae usually has one spine on the ischium of the second pereopod; P. fragilis , P. gracilis , P. laevis , and P. mclaughlinae n. sp. are unarmed on the posterior margin of the ischium and basis of the second pereopod.

The new species differs from P. fragilis , P. gracilis , and P. laevis in features of the abdomen and armature of the second pereopod. The abdomen of the new species is dorsally flat on the second to fifth somites and partly on the sixth somite. It is uncertain whether the posterior margin of the telson is provided with three or four pairs of spines, because five spines remain on the posterior margin in both types ( Fig. 2E, F ). Judging from these remaining spines, there may be four pairs in the holotype, but clearly three pairs are present in the paratype. The merus of the second pereopod is armed with five to seven spines on the posterior margin in the new species, whereas there are nine or more spines in P. fragilis , P. gracilis , and P. laevis . The meral spines on the first pereopod are also fewer in the new species than in those other three species, although there is overlap in the range of spines (four to six in the new species, six to nine in P.fragilis , seven to nine in P.gracilis and P. laevis ). In addition, the rostrum is short and small in P. fragilis and P. gracilis , and the branchiostegal sinus is barely distinguishable in P. laevis .

Figures

FIG. 1. — Pasiphaea mclaughlinae n. sp., ♂ holotype from Taiwan, cl 16.1 mm (MNHN-Na 16064): A, lateral view; B, transversal section of fifth abdominal somite. Scale bars: 2 mm.

FIG. 2. — Pasiphaea mclaughlinae n. sp.: A-C, E, G-K, ♂ paratype from Taiwan, cl 16.0 mm (MNHN-Na 16065); D, F, ♂ holotype from Taiwan, cl 16.1 mm (MNHN-Na 16064); A, anterior part of carapace with antennules and antennal peduncles, lateral; B, anterior part of carapace and right eye, dorsal; C, anterior margin of carapace, lateral; D, posterior part of third to sixth abdominal somites, lateral; E, posterior margin of sixth abdominal somite and telson, dorsal; F, posterior part of telson, dorsal; G, antenna, ventral; H, chela of right first pereopod, mesial; I, basal part of right first pereopod, mesial; J, basal part of right second pereopod, mesial; K, right side of gills, pereopods omitted. Scale bars: 1 mm.

FIG. 3. — Pasiphaeamclaughlinae n.sp.,♂paratype from Taiwan,cl16.0 mm (MNHN-Na16065) (all appendages areright side,lateral):A, man- dible;B, maxillule;C, maxilla;D, first maxilliped;E, second maxilliped;F, third maxilliped;G, first pereopod;H, second pereopod;I, third pere- opod;J, fourth pereopod; K, fifth pereopod;L, endopod of first pleopod;M, appendix masculina and appendix interna. Scale bars:1 mm.