Chauliopleona dentata Dojiri & Sieg, 1997

Larsen, Kim & Shimomura, Michitaka, 2007, Tanaidacea (Crustacea: Peracarida) from Japan. II. Tanaidomorpha from the East China Sea, the West Pacific Ocean and the Nansei Islands, Zootaxa 1464, pp. 1-43 : 38-41

Chauliopleona dentata Dojiri & Sieg, 1997

( Figs 20 and 21 )

Material examined. Paratypes (from California), 2 females, 1 male ( SBMNH 144123), Sta. 4C, 33°50.40’N, 118°26.22’W, 76 m. Non-type material, 1 female, 1 male ( SBMNH 36937), same locality; 1 female ( SBMNH 369416), Sta. 6B, 33°52.27’N, 118°34.12’W, 75 m; 6 females, 3 males, 2 mancas ( SBMNH 36418), Sta. R-4-3, 34°43.01’N, 120°47.23’W, 92 m; 5 females (1 dissected), 1 male, 2 mancas ( SBMNH 36420), Sta. R-4-1, 34°43.01’N, 120°47.23’W, 92 m; 1 female ( ZMH K- 40226), Antarctica (doubtful if this specimen is C. dentate), RV Victor Jensen Station 1270, 54°55.’S, 70°45’W, 135 m.

Diagnosis. Maxilliped basis with long seta at palp insertion.

Description (body of holotype, appendages of dissected paratype).

FEMALE (from California).

Body ( Fig. 20 A, B). Elongate, about 7.5 times as long as wide.

Carapace. Marginally shorter than pereonites 1 and 2 combined. Eyes absent.

Pereonites. Pereonites wider than long.

Pleon. Short (including pleotelson 25% total body length). All pleonites subequal, with small posterior protuberance. Pleonite 5 with ventral posterior-directed spine not protruding beyond pleotelson apex. Pleotelson longer than the lengths of two free pleonites combined, apex rounded, and covered by a dorsal plate.

Antennule ( Fig. 20 C). With 4 articles, shorter than carapace. Article 1 as long as rest of antennule, with one simple and several setulose distal/subdistal setae. Article 2 shorter than half of article 1, with five distal/ subdistal setae. Article 3 shorter than article 2, with 1 simple distal seta. Article 4 about as long as article 2, with five distal setae and one aesthetasc.

Antenna ( Fig. 20 D). 0.75 times as long as antennule. Article 1 wider than following articles. Article 2 shorter than article 1, with one distal seta. Article 3 longer than other articles, with clear fusion line and one setulose setae at fusion line, with five simple and one setulose distal setae. Article 4 longer than article 1, with one distal seta. Article 5 smallest, with four simple distal setae and one aesthetasc.

Mouthparts. Labrum ( Fig. 20 E, e1) with finely setose apex. Mandibular molar process tapering and longer than incisor, with small distal spines. Left mandible ( Fig. 20 F) lacinia mobilis of the same shape as incisor; incisor blunt, bifurcate. Right mandible ( Fig. 20 G) incisor bifurcate. Labium ( Fig. 20 H) consists of one pair of setose lobes, with small spine on anterolateral corners. Maxillule ( Fig. 20 I) endite with nine distal spiniform setae of which at least four are serrated; palp with two distal setae. Maxilla ( Fig. 20 J) remarkably large, wider at basis, with few setules at distal margin. Maxilliped ( Fig. 20 K) basis with long seta at palp insertion. Endites with two blunt inner and one spiniform outer distal processes, with one simple subdistal setae, almost as wide as basis. Palp article 1 naked; article 2 asymmetric, with three setae on inner margin and one larger seta on outer margin; article 3 with four setae on inner margin; article 4 narrower than article 3, with six distal setae. Epignath not recovered.

Cheliped ( Fig. 21 A). Basis unequally divided by prominent sclerite, shorter than carpus, with one distal seta. Merus triangular, with one ventromedial seta. Carpus longer than propodus (including fixed finger), with two ventromedial setae, one small dorsal seta at each end. Propodus robust and with high dorsal crest and row of small setae on inner margin by dactylus insertion. Fixed finger with two setae ventrally and three on inner margin, with only weak denticulation on inner margin. Dactylus as long as fixed finger, with one outer seta, with only very weak dorsal crennulation.

Pereopod 1 ( Fig. 21 B). Coxa with one seta. Basis longer than the three succeeding articles combined, with one setulated dorsal seta. Ischium with one seta. Merus as long as carpus, widening distally and with one long spiniform and one smaller distal setae. Carpus more than half as long as propodus, with two long and one short spiniform distal setae and one simple seta. Propodus more than half as long as basis, with one spiniform ventral and one small simple distal setae and dorsal spine, ventral margin without spinules. Dactylus and unguis not fused, combined as long as propodus.

Pereopod 2 ( Fig. 21 C). As pereopod 1 except: basis naked; carpus with three spiniform and two simple distal setae; dactylus with small seta.

Pereopod 3 ( Fig. 21 D). As pereopod 2 except; basis with additional distal setae; ischium with two setae.

Pereopod 4 ( Fig. 21 E). No visible coxa. Basis stouter than those of pereopods 1–3, naked. Ischium with two setae. Merus with two spiniform setae. Carpus with three spiniform and one simple distal setae. Propodus with three spiniform distal setae. Dactylus and unguis combined as long as propodus, with rows of small ventral spines. Unguis less than half as long as dactylus.

Pereopod 5 ( Fig. 21 F). As pereopod 4 except: basis with two setulated setae.

Pereopod 6 ( Fig. 21 G). As pereopod 4 except: propodus with five spiniform distal setae and dorsal spine.

Pleopods ( Fig. 21 H). All pairs subequal. Basal article wit large circumplumose seta. Exopod with 12 plumose inner setae and one outer seta. Endopod 21 plumose setae. Both rami without gap between proximal seta and other setae.

Uropod ( Fig. 21 I). Longer than pleotelson. Basal article short (shorter than exopod), with one or two setae. Endopod with two articles; article 1 with two setulated distal setae; article 2 as long as article 1, with four long and two short simple distal setae. Exopod with two articles, shorter than first endopod article; article 1 with one long distal seta; article 2 with two unequal setae distally.

Remarks. Several problems are currently connected with this species. Chauliopleona dentata sensu stricto is incompletely described ( Dojiri & Sieg, 1997:231, pl. 17) and while the redescription by Guerrero- Kommritz (2005: 1180-84) is better, his re-description is based on a specimen collected from the Antarctic. As the type locality of C. dentata is Santa Monica Bay, California, such distribution is unlikely (see Larsen 2005 for review of Tanaidacean distribution patterns). Examination of C. dentata material from the typo locality (from SBMNH material as the extensive material in the NHMLAC could not be located and is presumed lost (G.E. Davis, pers. comm.)), revealed a number of problems with important characters: 1) the dorsal crennulation on the cheliped dactylus is very variably, even between the left and right cheliped, to the point of being absent in some specimens. This character is not unique to C. dentata as it is also found in Chauliopleona paradoxa Guerrero-Kommritz, 2005 . 2) The spatulate spinules on the propodus of pereopod 1 are described as being present on females with marsupium only, while attenuated in non-ovigerous females and neuters ( Dojiri & Sieg 1997:233). The spatulate spinules, however, are clearly present in the Chauliopleona cf dentata from Antarctica described by Guerrero-Kommritz (2005) but this is from a non-ovigerous female. The specimen dissected from the type locality in this study, was ovigerous but did not display these spinules. 3) The three small setae on the uropodal basal article, mentioned by both Dojiri & Sieg (1997:233, pl. 3.17) and Guerrero- Kommritz (2005:1180 & 1183, fig. 1g) are also variable (from 1–3) and not diagnostic. Furthermore the long maxilliped basal seta on the material from the type locality, are not present on Chauliopleona dentata from Antarctica. Studies applying molecular techniques ( Larsen 2001) have illustrated the problems with sister species, thus it is doubtful whether Guerrero-Kommritz’s re-described female really are C. dentata or morphologically similar but different species.

Figures

FIGURE 20. Chauliopleona dentata Dojiri & Sieg, 1997, female (from type locality). A, dorsal view; B, later view C, antennule; D, antenna; E, labrum, lateral view; E 1, same dorsal view; F, left mandible; G, right mandible; H, labium; I, maxillule; J, maxilla; K, maxilliped. Scale bar mouthparts = 0.2. mm, other appendages scale bar = 0.5 mm.

FIGURE 21. Chauliopleona dentata Dojiri & Sieg, 1997, female (from type locality). A, cheliped; B, pereopod 1; C, pereopod 2; D, pereopod 3; E, pereopod 4; F, pereopod 5; G, pereopod 6; H, pleopod; I, uropod. Scale bar = 0.2 mm.