Paralophogaster glaber Hansen, 1910

Paralophogaster glaber Hansen, 1910 View in CoL

( Fig. 7 View Fig )

Paralophogaster glaber Hansen, 1910: 16 View in CoL , pl. 1, fig.

2a–n: W. M. Tattersall, 1923: 279; — 1951: 22;

Băcescu, 1981: 270, fig. 3a–k; — 1991: 92, fig. 2f–h;

Casanova, 1993: 44, fig. 7a, b; — 1996: 141; — 1997:

99; Yolanda et al., 2023b: 419; Hernández-Payán et al., 2023: 5.

ʁ Paralophogaster glaber pacificus Vereshchaka, 1990:

119, fig. 1.

Material examined. Western Pacific. Central Japan: Suruga Bay ; 1 female (cl 3.0 mm), KT-65-9, St. 111-1, 34°30.1′N 138°30.5′E – 34°31.2′N 138°33.7′E, 1000–0 m, ORI net, 24 Apr 1965, coll. M. Murano (NSMT-Cr 32900). East GoogleMaps China Sea. 2 females (cl 3.0, 3.5 mm), 4 ovig. females (cl 3.0– 3.6 mm), KH-74-3, St. B 11- 1, 31°15.7′N 128°20.6′E – 31°17.5′N 128°22.1′E, 364–369m, 3 m Beam Trawl , 5 Aug 1974, coll. M. Murano (NSMT-Cr 32901) GoogleMaps .

Diagnosis. Integument rather fragile.

Carapace ( Fig. 7a View Fig ) with rostral plate of onionshaped structure in dorsal view, antero-lateral margin slightly convex, leading to short median rostral tooth; pair of short teeth at antero-lateral corner; lateral parts of rostral plate curving upwards, forming weakly elevated rims in lateral aspect; median dorsal tubercle placed just posterior to rostral plate.

Eye ( Fig. 7a View Fig ) large, cornea 1.45–1.55 times as broad as rostral plate.

Antennal scale ( Fig. 7a View Fig ) rather long, extending beyond antennular peduncle by slightly more than 1/3 length of blade, and about 4 times as long as wide; lateral margin nearly straight, bearing short tooth falling far short of anterior end of blade; sub-terminal suture present.

Telson ( Fig. 7b View Fig ) as long as or slightly shorter than sixth abdominal somite, noticeably narrowing posteriorly beyond sub-terminal stout setal-spines, bearing 5 or 6 feeble setal-spinules on lateral margin and pair of long sub-terminal spines extending far beyond posterior end of telson, bearing 4 or 5 moderate spines increasing in length posteriorly between these 2 stout spine pairs; postero-median plate noticeable, possessing most probably 5 short spinules and 4 plumose setae.

Uropod ( Fig. 7c View Fig ) with endopod bearing stout ventral setal-spine in basal part.

Remarks. Although Băcescu (1981) (see also Hansen, 1910, Pl. 1, fig. 2b) showed the presence of two stout inner basal spines on the antennal flagellum, only a single spine can be seen in our specimens. In addition, the ventral spine on the endopod of the uropod appears to be less developed as compared with that shown by Băcescu.

Müller (1993) regarded that Paralophogaster glaber pacificus reported by Vereshchaka (1990) from the waters around the Nazka and Sala y Gómez ridges could be a synonym of P. glaber . However, as noted by Hernández-Payán (2023), the structure of the telson of the south-eastern Pacific specimens differs from that of the western Pacific population (e.g., Hansen, 1910; W. M. Tattersall, 1951; Băcescu 1981, 1991; Casanova, 1996).

Contrary to this, Hernández-Payán (2023) mentioned that their specimens collected off Chile showed the typical form of the western Pacific population in the identical part.

Thus, the identity of the south-eastern Pacific subspecies of P. glaber should be re-assessed in the future studies. Furthermore, a taxonomic review for such eurychoric species is strongly recommended over its geographical scale in order to verify the origin and/or diversification of the local populations.

Distribution. According to the published literature, this species is known to distribute in the Atlantic and Indo-Pacific Oceans (see W.M. Tattersall, 1951; Müller, 1993; Hernández-Payán et al., 2023).

Paralophogaster philippinensis Băcescu, 1981 View in CoL

( Figs. 8 View Fig , 9 View Fig )

Paralophogaster philippinensis Băcescu, 1981: 267 View in CoL , figs. 3 m, n, 4a–j: — 1985: 356; Casanova, 1993, 45: figs. 4c–e, 7e, f; — 1996: 143; Saitoh and Kajihara, 2002: 22, fig. 4; Yolanda et al., 2023b: 419 View Cited Treatment .

Material examined. West Pacific. Central

Japan: Sagami Bay ; 1 juv. (cl 1.5 mm), KT-64- 1, St. 3-8, 35°11.5′N 139°15.9′E – 35°11.6′N 139°15.6′E, 260–0m, Larva Net, 22 Jan 1964, coll. M. Murano (NSMT-Cr 32902); — Suruga

Bay, off Matsu-zaki; 3 males (cl 2.2–3.3 mm), 4 females (cl 3.4–4.0 mm), 2 ovig. females (cl 4.8, 5.0 mm), KT-74-14, St. B3, 144– 135 m, 2 m Beam Trawl, 21 Sept 1974, coll. M. Murano (NSMT-Cr 32903); — Suruga Bay , off Kunosan; 2 males (cl 3.0, 3.2 mm), KT-77-7, St. K, 123– 81 m, 2 m Beam Trawl, 12 June 1977, coll. M. Murano (NSMT-Cr 32904); — Suruga Bay ,

Uchiura-wan; 1 female (cl 5.5 mm), KT-78-11, St. OT-6(II), 115– 108 m, 2 m Beam Trawl, 14 July 1978, coll. M. Murano (NSMT-Cr 32905); — Suruga Bay , off Toi; 4 females (cl 3.0– 4.0 mm), KT-78-18, St. OT-6, 105– 98 m, 2 m Beam Trawl, 20 Nov 1978, coll. M. Murano (NSMT-Cr 32906);,— 42 males (cl 2.5–4.0 mm),

40 females (cl 2.7–4.2 mm), 2 ovig. females (cl 4.2, 4.5 mm), 25 juvs & damaged inds (cl 2.4– 3.5 mm), KT-78-18, St. OT-7, 160– 145 m, 2 m Beam Trawl , 20 Nov 1978, coll. M. Murano (NSMT-Cr 32907); — Western Japan: off

Kochi; 1 male (cl 3.7 mm) , 1 female (cl 4.5 mm), 170 m, 2 June 1983, other details unknown (NSMT-Cr 32908). Sea of Japan. 1 female (cl ca 4.0 mm), KH-70-4, St. 137-1, 37°50.7′N 136°41.6′E – 37°52.2′N 136°38.8′E, 140–0 m, IKMT, 9 Aug 1970, coll. M. Murano (NSMT-Cr 32909). East GoogleMaps China Sea. 6 males (cl 2.0– 4.0 mm), 4 females (cl 2.5–3.7 mm), 1 ind. (damaged), KH-74-3, St. B13, 31°36.9′N 127°06. 5′E – 31°38.5′N 127°08.8′E, 110– 110 m, 3 m Beam Trawl, 6 Aug 1974, coll. M. Murano (NSMT-Cr 32910) GoogleMaps .

Diagnosis. Integument of body ( Fig. 8 View Fig ) rather fragile.

Carapace ( Fig. 9a, b View Fig ) with rostral plate somewhat pentagonal in dorsal view, not converging posteriorly but running almost parallel to each other; anterior margin feebly convex or nearly straight, leading to short median rostral tooth: pair of short teeth placed antero-lateral corner; lateral parts of rostral plate curving upwards, forming well marked elevated rims in lateral aspect; small median dorsal tubercle present just posterior to rostral plate.

Telson ( Fig. 9c View Fig ) as long as or slightly longer than sixth abdominal somite, gradually narrowing posteriorly, with 5–7 short setal-spinules along lateral margin; moderately large sub-terminal setal-spine falling far short of posterior end of telson and much shorter than terminal setal-spines, bearing 4 or 5 moderate setal-spines increasing in length posteriorly between terminal and sub-terminal stout spines; postero-median plate noticeable, most probably with 5 denticles and 4 plumose setae.

Uropod ( Fig. 9d View Fig ) with endopod commonly with 2, infrequently 3, moderate setal-spines in basal part of ventral side.

Eye ( Fig. 9a, b View Fig ) with cornea 1.60–1.75 times as broad as rostral plate.

Antennal scale ( Fig. 9a, b View Fig ) rather long, extending beyond antennular peduncle by about 1/3 length of blade, about 4 times as long as wide; lateral margin nearly straight, bearing short tooth falling far short of anterior end of blade; sub-terminal suture present.

Distribution. This species is known from Japan, Philippines, Indonesia, and New Caledonia, and captured in abundance around the Japanese coastal waters. According to our survey, this species appears to commonly inhabit in depths shallower than 200 m.