Petalosarsia brevirostris Gamô, 1986

Akiyama, Tadashi & Gerken, Sarah, 2012, The Cumacean (Crustacea: Peracarida) Genus Petalosarsia (Pseudocumatidae) from the Pacific Ocean, Zootaxa 3320, pp. 1-35 : 6-7

Petalosarsia brevirostris Gamô, 1986

( Fig. 3 )

Petalosarsia brevirostris Gamô, 1986: 5 –10, Figs. 2 , 3 .

Material examined. Twenty-five ovigerous females (5 specimens dissected, 3.40–3.88 mm) (NSMT-Cr 22064), Enshu Nada, off Honshu Island, 34°36.11ˏN, 137°59.06ˏE – 34°36.01ˏN, 137°59.27ˏE, 116–155 m (KT -02-5, St.

EN-4-2), 27 May 2002; many ovigerous females (4 specimens dissected, 3.51–3.60 mm), many preparatory females, 3.20–3.42 mm, many adult males, (5 specimens dissected, 4.66–4.76 mm) (NSMT-Cr 22065), East China Sea, 31°19.39ˏN, 128°19.73ˏE, 305 m (N282, St. W-5), 8 June, 2009; 1 preparatory female, Ashizuri Misaki, Shikoku Island, 32°44.3ˏN, 132°41.1ˏE, 124–125 m (KT-99-18, St. DG-8), 17 December, 1999; 1 preparatory female, 1 adult male, Enshu Nada, 34°35.37ˏN, 138°04.88ˏE, 115–117 m (KT-02-5, St. EN-2-1-1), 26 May 2002; 1 preparatory female, 6 adult males, 2 juveniles, Enshu Nada, off Honshu Island, 34°34.78ˏN, 138°04.89ˏE, 69–74 m (KT-02-5, St. EN2-2), 26 May 2002; 2 preparatory females, 2 adult males, 2 juveniles, east of Izu Peninsula, Honshu Island,34°41.11ˏN, 139°00.78ˏE, 86–96 m (KT-02-5, St. IZE-3) 29 May 2002; 1 ovigerous female, 1 juvenile male, 34°50.88ˏN, 138°44.78ˏE 130–134 m (KT-02-5, St. IZW-1), 29 May 2002; 9 ovigerous females, 7 preparatory females 8 adult males, 2 subadult males, 1 juvenile, off Okinoshima, 32°43.95ˏN, 134°41.99ˏE, 131–136 m (KT-05-30, St. OS-1-2), 22 November 2005; 1 subadult male, off Okinoshima, 32°41.07ˏN, 134°42.17ˏE 181–183 m (KT-05-30, St. OS-2), 22 November 2005; 1 preparatory female, 2.69 mm (NSMT-Cr 22066), the Sulu Sea, 07°56.50ˏN, 118°10.09ˏE – 07°55.36ˏN, 118°10.33ˏE, 292–296 m (KH-02-4, St. S1-B), 23 November 2002.

Distribution. Pacific coast of southern Japan, off Kyusyu and Nansei Isles, East China Sea, Sulu Sea, Philippines, 69– 609 m.

Remarks. Specimens agree well with the description by Gamô (1986). However, minor alterations and additional descriptions include:

(1) basis of maxilliped 2 of females with round thin plate on ventral surface and a short simple seta on inner margin near basal end; ventral surface near distal end with a few spines ( Fig. 3 E).

(2) Gamô observed minute exopods on pereopods 3 and 4, which were "difficult to see" in a female specimen from the southern coast of Honshu Island. In the present study, exopods on these legs were absent except for a couple of possible remnant terminal setae in the female specimens from the southern coast of Honshu, near the locality where Gamô's specimens were collected. However, bi-articulate exopods were present in most specimens collected off Kyushu and Nansei Islands, the East China Sea. Thus this character is variable between individuals.

(3) the main flagellum of antenna 1 in adult males is 5-articulate, which is common with other species examined in the present study.

(4) Gamô described the adult male of P. brevirostris with five pairs of pleopods, 3rd to 5th of which are of minute button-like single article, furnished with a terminal plumose seta. McCarthy et al. (2005) suspected that these minute projection on pleonite 3–5 were not actually pleopods, but plumose setae observed occasionally in male cumacean specimens. Adult male specimens examined in the present study do not have pleopod articles on pleonite 3–5, but only plumose setae, examined under a light microscope. Thus the males have only two pairs of pleopods.

(5) Inner and outer rami of pleopod 1 are partially fused; outer ramus with a short, robust naked seta on posterior side (indicated by arrowhead in Fig. 3 G).

(6) Telson of adult males is triangular, exceeding opening of anus.

A specimen collected from the Sulu Sea is characterized by the dorsolateral carina on the carapace bearing three faint teeth, whereas Japanese specimens have 8–13 teeth. However, this character may reflect that the specimen was damaged during collection or preservation.

Figures

FIGURE 2. Petalosarsia declivis (Sars), ovigerous female. A, B, pereopod 3; C, D, pereopod 4; E pereopod 5; F, uropod with pleonite 6.

FIGURE 3. Petalosarsia brevirostris Gamô. Ovigerous female; A, habitus, lateral view; B anterior portion of body, dorsal view; E, maxilliped 2; F, pereopod 1. Adult male; C, habitus, lateral view; D, anterior portion of body, dorsal view; G, pleopod 1.