Lophogaster pacificus Fage, 1940

Lophogaster pacificus Fage, 1940 View in CoL

( Fig. 5 View Fig )

Lophogaster typicus View in CoL : Ortmann, 1906: 967 (in part, not M. Sars, 1857)

Lophogaster pacificus Fage, 1940 View in CoL ; 324; — 1942: 29, figs. 18a–d, 24b, 25a, 26, 27; Murano, 1970: 3, fig. 1e–i; Băcescu, 1985: 363, fig. 1a–f; — 1991: 88 (part); Wang and Liu, 1994: 64, fig. 2; — 1997: 195: Liu and Wang, 2000: 61, fig. 2.

Not Lophogaster pacificus View in CoL : O. S. Tattersall, 1960: 534, fig. 3; Băcescu, 1981: 265, figs. 1c–i, 2a–i; — 1991: 88 (at least in part) (= L. japonicus W. M. Tattersall, 1951 View in CoL )

Material examined. East China Sea. 1 male (cl 4.2 mm) , 2 females (cl 6.0, 6.2 mm), 1 juv. (cl 2.8 mm), KH-74-3, St. B 13, 31°36.9′N 127°06. 5′E – 31°38.5′N 127°08.8′E, 110– 110 m, inner net of 3 m Beam Trawl , 6 Aug 1974, coll. M. Murano (NSMT-Cr 32887) GoogleMaps . Sahul Shelf. 1 juv. (cl 1.2 mm) (id tentative), KH-72-1, St. 29, 12°17.3′S 129°40.9′E – 12°17.2′S 129°41.8′E, 52– 49 m, inner net of 3 m Beam Trawl , 24 June 1972, coll. M. Murano (NSMT-Cr 32888) GoogleMaps .

Diagnosis. Body somewhat calcified.

Carapace ( Fig. 5a, b View Fig ) with distinct post-ocular processes as well as numerous tubercles of different sizes and shapes scattered on dorsal surface; rostral plate slightly narrowing anteriorly, small part of eye-stalk exposed but completely covering basal 2 segments of antennular peduncle in dorsal view, with sharp tooth at antero-lateral corner; rostral process weakly curving upwards, barely reaching anterior end of antennular peduncle; low carina running on branchial region of carapace; postero-lateral tooth (alar spine) moderately long, directed obliquely upwards.

Abdomen ( Fig. 5c View Fig ) in both sexes with sharp ventral process on anterior 5 somites, decreasing its height posteriorly; postero-ventral corner of fifth pleuron angulate or with minute process; sixth somite about 1.3 times as long as fifth.

Telson ( Fig. 5c, d View Fig ) about 1.8 times as long as sixth abdominal somite, with somewhat low median tubercle in basal part, dorsal surface slightly sulcate posteriorly; lateral margin armed commonly with 2 pairs of setal-spines in addition to ordinary 2 distal pairs; median part of posterior margin weakly produced, bearing 4 short setal-spines and 2 plumose setae.

Exopod of uropod ( Fig. 5c View Fig ) slightly shorter than endopod, outer margin smooth, ending in triangular process; endopod reaching near mid-length between distal end and posterior pair of lateral setal-spines of telson.

Antennular lamina ( Fig. 5e View Fig ) with widely rounded major lobe but no projection at inner distal corner forming obtuse shoulder, with single seta near inner base of major lobe.

Antennal scale ( Fig. 5f View Fig ) sub-triangular in general form, apical tooth slightly curving inwards; outer margin weakly convex, bearing 5, occasionally 4, denticles on distal two-thirds.

Endopod of seventh thoracopod ( Fig. 5 g View Fig ) with short tooth on pre-coxa.

Remarks. As aforementioned, several early researchers considered Lophogaster pacificus to be a senior synonym over L. japonicus , but the difference between these two species was explic- itly discussed by Murano (1970) (see l Remarks z under L. japonicus ).

In addition to the previous observations, it appears that this species has a relatively longer postero-lateral carapace tooth (= alar spine) as compared with that of L. japonicus .

Distribution. This species has been collected from the tropical to temperate regions of the western Pacific, including its marginal seas.