Patonia, Mitsuhashi & Chan, 2006

Mitsuhashi, Masako & Chan, Tin-Yam, 2006, A new genus and species of deep-water pontoniine shrimp (Decapoda, Caridea, Palaemonidae) from Taiwan, Zoosystema 28 (2), pp. 389-398 : 390-391

Genus Patonia n. gen.

TYPE SPECIES. — Patonia mclaughlinae n. sp., by present designation.

ETYMOLOGY. — The abbreviated form of the first name of Dr Patsy A. McLaughlin, Pat, is used as prefix for this pontoniine genus. The new name is given in honor of her many important contributions to the taxonomy and phylogeny of decapod crustaceans.

DIAGNOSIS

Body moderately compressed laterally.Rostrum well developed, exceeding eye, lateral carina well marked, almost entire dorsal margin serrated with distinct teeth, some bearing basal suture; lower margin unarmed. Carapace glabrous; inferior orbital angle distinct; antennal spine submarginal; supraorbital and epigastric spines absent; hepatic spine large, with distinct basal suture and possibly mobile. Abdomen smooth, third somite not posteriorly produced, pleura rounded. Telson elongate, with two pairs of dorsal and three pairs of posterior spines. Eyes well developed. Antennule slender, anterolateral end of basal segment multidentate. Antenna bearing basicerite spine, scaphocerite well developed. Epistome unarmed. Fourth thoracic sternite without median projection. Mandible without palp. Maxillula with bilobed palp, lower lacinia slender. Maxilla with simple palp, basal endite deeply bilobed, distally setose. First maxilliped with long and slender palp, exopod with large caridean lobe, flagellum well developed, coxal endite fused with basal endite, epipod large and bilobed. Second maxilliped with normal endopod, exopod distally setose, epipod subrectangular, podobranch absent. Third maxilliped with slender endopod, ischiomerus fused with basis, arthrobranch rudimentary. All pereiopods slender. First pereiopod similar to second pereiopod but much shorter. Second pereiopods similar, segments unarmed; chela with fingers simple, closing entirely, with cutting edges unarmed; carpus longer than chela. Third to fifth pereiopods with biunguiculate dactyli; ventral margins of propodi bearing few minute spinules; meri lacking distal tooth. Uropod with protopodite unarmed posterolaterally, exopod with small distolateral spine accompanied with larger movable spine medially.

SYSTEMATIC POSITION

The large hepatic spine with a complete basal suture and possibly mobile in this new genus is remarkable amongst the subfamily Pontoniinae . Only four pontoniine genera have movable hepatic spines. They are Dasella Lebour, 1945 , Paranchistus Holthuis, 1952 , Allopontonia Bruce, 1972 and Zenopontonia Bruce, 1975 (see Chace & Bruce 1993; Holthuis 1993; Bruce 1994). The new genus differs from Dasella

A new pontoniine shrimp genus from Taiwan and Paranchistus in having the dorsal border of the rostrum entirely serrated with distinct teeth. Dasella and Paranchistus have the dorsal margin of the rostrum smooth or only armed distally. Allopontonia differs from the new genus in having a ventrally dentate rostrum, much stouter second pereiopod with the carpus only about 1/3 the length of the palm, and the distal two segments of the posterior pereiopods densely serrated with ventral spinules. The new genus has a laterally compressed body, whereas Zenopontonia has a subcylindrical body. Moreover, Zenopontonia also has stout second pereiopods with the carpus much shorter than the chela, and the dactyli of the posterior pereiopods terminate in a single spine.

Except for the basal suture of the hepatic spine, Patonia mclaughlinae n. gen., n. sp. might be placed under Periclimenes Costa, 1844 as defined by Chace & Bruce (1993) and Bruce (1994). Periclimenes now includes over 140 species and is extremely diverse in morphology ( Li 2000; Bruce 2004; Bruce et al. 2005). The monophyly of Periclimenes has been questioned, and some species have already been separated (e.g., Duris & Bruce 1995; Bruce 2004; Bruce et al. 2005). Two species of Periclimenes , P. perturbans Bruce, 1978 and P. priodactylus Bruce, 1992 , have a “possibly mobile” ( Bruce 1978: 253) or “? mobile” ( Bruce 1992: 53) hepatic spine, respectively. Whether these two could be assigned to Patonia n. gen. will require studies of more specimens, as well as a phylogenetic evaluation of the family.