Paranesotanais Larsen and Shimomura, 2008

Kakui, Keiichi & Yamasaki, Hiroshi, 2013, Nototanaids (Crustacea: Tanaidacea) from Japan, with the Description of a New Species of Nototanoides, Species Diversity 18, pp. 245-254 : 252

Genus Paranesotanais Larsen and Shimomura, 2008 Paranesotanais longicephalus Larsen and Shimomura, 2008

( Fig. 6 )

Paranesotanais longicephalus Larsen and Shimomura, 2008 , 10–22.

Paranesotanais malignus: Bird 2012a , table 1.

Material examined. One female, ZIHU-4411; BL 2.29, CW 0.30; one slide and one vial; 28°11′14″N, 129°14′34″E (retrieved from Google Earth), Kakeroma Island, Amami Islands, 1–4 m, coral sand, 28 June 2006, collected by Tadashi Akiyama. One male, ZIHU-4412; BL 2.80, CW 0.28; two slides and one vial; same collection data as for ZIHU-4411 .

Partial redescription of both sexes. Rostrum bilobed ( Fig. 6A ). Each pleonite with two pairs (one pair on pleonite 5) of lateral simple setae; pleonites 1 and 5 with one pair of dorsolateral simple seta ( Fig. 6B ).

Female antennule ( Fig. 6C ) with three articles; length ratio of articles 1–3 5.20: 1.00: 1.45. Article 1 with two outer and two inner simple setae, and several plumose sensory setae. Article 2 with two simple setae and one plumose sensory seta. Article 3 with six distal simple setae, one distal plumose sensory seta, and one distal and three proximal aesthetascs.

Male antennule ( Fig. 6D ) with four articles; length ratio of articles 1–4 8.16: 1.20: 1.00: 1.18. Articles 1 and 2 similar to those of female. Article 3 with three distal aesthetascs. Article 4 similar to that of female except lacking proximal aesthetascs.

Male maxillular palp ( Fig. 6E ) with four setae. Male maxillipeds ( Fig. 6F ) firmly connected with exoskeleton of cephalothorax. Bases fused medially, with one pair of simple setae. Endites absent. Palp with four articles; article 4 with one bifurcate lamellar seta.

Pereopods 4–6 with ventral pit in unguis ( Fig. 6G ).

Remarks. As Larsen and Shimomura’s (2008) figures indicate, male and female P. longicephalus both have a bilobed rostrum ( Fig. 6A ) and bear two pairs (one pair in pleonite 5) of lateral simple setae on each pleonite ( Fig. 6B ). These characters, at least, distinguish this genus from confamilial genera (see Discussion below).

The antennule in our female of P. longicephalus has four aesthetascs on article 3, three in the proximal region and another in the distal region ( Fig. 6C ). Although Larsen and Shimomura (2008: fig. 5C) found only two aesthetascs in the distal region of antennular article 2, their specimens might show the same condition as our specimen. Our male specimen bears three aesthetascs on article 3 of antennule and one at the tip of article 4. Larsen and Shimomura (2008: fig. 8C) illustrated three and two aesthetascs on articles 3 and 4, respectively, but did not mention these numbers in the description, simply noting (p. 12), “Article 3–4 with several aesthetasc.” Considering the number of simple setae on article 4 in their fig. 8C, one simple seta may have been misidentified as an aesthetasc.

Distribution. So far, this species is known from shallow subtidal bottoms at depths of 1–6.5 m in the Kerama and Amami Islands ( Larsen and Shimomura 2008; this study).

Figures

Fig. 6. Paranesotanais longicephalus Larsen and Shimomura, 2008. A–C, G, female; D–F, male. A, rostrum, dorsal view; B, pleon with uropodal bases, dorsal view; C, right antennule, ventral view; D, right antennule, dorsal view; E, left maxillular palp; F, maxillipeds, anteriorright-ventral view; G, distal region of right pereopod 4, outer view. Scale bars: A, B, D, 0.1mm; C, E–G, 0.05mm.