Ampithoe tarasovi Bulycheva, 1952

Figures 4, 5, 6, 7, 8

Ampithoe tarasovi Bulycheva, 1952: 246, fig. 38. Tzvetkova 1967: 190.

Type material.

Male, collected by Tarasov from De-Kastri, Sea of Japan, 3 Aug. 1929.

Description.

Based on holotype male, 14.3 mm (re-measured along the midbody line from the tip of the rostrum to the posterior end of urosomite 3), deposited at the Moscow Museum, Russia (no. 1/21349).

Head (Fig. 4B). Upper lip (Fig. 4C) with mid-lateral notch on margins.

Mandible (Fig. 4D, E) molar well developed, triturating; accessory setal row with 9 robust setae; palp apically setose, 3-articulate; mandibular palp (Fig. 4F) article 1 shorter than article 2 (0.6 times article 2); article 2 shorter than article 3 (0.7 times article 3); article 3 long (3.3 times as long as wide), longer than article 1 (2.3 times article 1).

Lower lip (Fig. 4G) outer plates forming a medial excavation, lateral lobe much longer than medial lobe; mandibular lobe curved laterally, rounded apically.

Maxilla 1 (Fig. 5A) inner plate with 1 slender seta; palp well developed, with apical robust setae.

Maxilla 2 (Fig. 5B) inner plate narrower than outer plate, with oblique setal row.

Maxilliped (Figs 5C-E, 6A) outer plate with developed row of large robust setae along medial margin.

Pereon. Gnathopod 1 (Fig. 6B) sexually dimorphic, smaller than gnathopod 2, carpus and propodus with numerous plumose setae on both anterior and posterior margins; coxa subequal to coxa 2 in length, broader than deep, anterior margin straight, anteroventral corner produced, rounded; basis longer than coxa, anterodistal lobe large and rounded; ischium anterior margin with large rounded lobe; merus posterodistal corner subquadrate; carpus about 2 times as long as broad, longer than merus, longer than propodus (1.8 times propodus), with posterodistal lobe slightly overlapping propodus, posterior margin straight; propodus broad, 1.4 times as wide as long, subovoid; palm acute, convex, defining corner rounded with 1 robust seta; dactylus subequal in length to palm.

Gnathopod 2 (Figs 6C, 7A) sexually dimorphic; basis longer than coxa, with sparse slender setae, anterodistal lobe large and rounded, not reaching beyond ischium; ischium anterior margin with subquadrate lobe; carpus much shorter than propodus (0.3 times propodus), subtriangular; propodus narrow, 2.3 times as long as wide, subrectangular; palm transverse, with a sloped quadrate mid-medial hump and an apically rounded defining tooth on posterodistal corner; dactylus slightly overreaching palm, curved, robust, apically blunt, without unguis.

Pereopod 3 (Fig. 8C) basis narrow; merus narrow; carpus about twice as long as broad.

Pereopod 4 (Fig. 8D) basis similar to pereopod 3.

Pereopod 5 (Fig. 8E) coxa simple and subrectangular. Pereopods 5-7 lost.

Pleon. Epimera 1-3 (Fig. 4A) with lateral ridges; ventral margin of epimera 2 and 3 straight, with distinct tooth on each posteroventral angle. Epimeron 1 subrounded posterodistally, with tooth on posteroventral angle; epimeron 2 subrounded posterodistally; epimeron 3 straight and sloped posterodistally.

Uropod 1 (Fig. 7B, C) reaching to end of uropod 2 rami; peduncle with 10 robust setae; inner ramus longer than outer ramus, with 5 marginal robust setae; outer ramus slender, about 6 times as long as broad, with 14 marginal robust setae.

Uropod 2 (Fig. 7D) peduncle with 8 robust setae; inner ramus longer than outer ramus, with 8 marginal robust setae; outer ramus 11 marginal robust setae.

Uropod 3 (Fig. 7E) peduncle much longer than broad (2.3 times width), 2.2 times as long as rami, with 3 marginal robust setae, marginal slender setae present, with 8 distal peduncular robust setae; rami long, about twice as long as broad; outer ramus shorter than inner ramus, with 2 large recurved distal robust setae and 1 dorsal robust setae, with lateral setal fringe; inner ramus with 6 distal robust setae, with 2 lateral robust setae both inner and outer margins, respectively.

Telson (Fig. 7F) subtriangular, apically subacute, with small apical cusps, with 4 or 5 of lateral setae on both margins, and 2 pairs of lateral plumose setae, with 2 or 3 submedial setae on both margins.

Sexual dimorphic female, 15.3 mm.

Gnathopod 1 (Fig. 8A) subequal in size to gnathopod 2; coxa about as broad as long, anterior margin concave, anteroventral corner produced and subacute; basis subequal in length to coxa, with sparse slender setae, anterodistal lobe large and rounded; carpus subequal in length to propodus (1.1 times propodus); propodus narrow, 2 times as long as wide, subtriangular; palm acute, straight, defining corner subrounded with 1 robust seta; dactylus slightly overreaching palm, inner margin crenate.

Gnathopod 2 (Fig. 8B) basis shorter than coxa, with sparse slender setae, anterodistal lobe large and rounded, not reaching beyond ischium; ischium anterior margin without distinct lobe; carpus shorter than propodus (0.7 times propodus); propodus narrow, 1.6 times as long as wide, subrectangular; palm acute, defining corner subrounded with 1 robust seta; dactylus slightly overreaching palm, tapering evenly, apically acute, inner margin crenate.

Depth zone.

Sublittoral (0-24 m).

Distribution.

Peter the Great Bay, Sea of Japan.

Remarks.

This species has the following characteristics: the apical and medial lobes of the outer lobes are separated in the lower lip; the carpus of male gnathopod 1 is about 1.8 times as long as the propodus; the palm of the male gnathopod 2 has a sloped quadrate hump and posterodistal tooth. Bulycheva (1952) noted that A. tarasovi is very abundant in macroalgae and reefs in Petra Velikogo Bay and in the northern Sea of Japan.