Ampithoe changbaensis, Shin & Coleman, 2021

Shin, Myung-Hwa & Coleman, Charles Oliver, 2021, A new species of Ampithoe (Amphipoda, Ampithoidae) from Korea, with a redescription of A. tarasovi, ZooKeys 1079, pp. 129-143 : 129

Ampithoe changbaensis sp. nov.

Figures 1 , 2 , 3

Ampithoe lacertosa : Kim and Kim 1987: 3, fig. 2. Kim and Kim 1988: 109, fig. 2A [not Ampithoe lacertosa Bate, 1858].

Ampithoe tarasovi : Shin et al. 2010: 300, figs 4-6 [not Ampithoe tarasovi Bulycheva, 1952].

Type locality.

Hamo beach, Jeju-do, South Korea.

Type material.

Holotype. Male, 17.6 mm (MABIK CR00248547), Hamo beach, Daejeong-eup, Seogwipo-si, Jejo-do, Korea (33°12'37.01"N, 126°15'44.34"E), 30 May 2007, coll. Shin and Hong.

Paratype. Female, 22.3 mm (MABIK CR00248548); male and female, 16-21 mm (MABIK CR00248549); 2 males and 1 female, 17-20 mm (MABIK CR00248550), same data as the holotype.

Additional material examined.

3 males, Hamo beach (MABIK CR00248551), Daejeong-eup, Seogwipo-si, Jeju-do, Korea (33°12'37.01"N, 126°15'44.34"E), 30 May 2007 ; 3 males and female (MABIK CR00248552), Gujwa-eup , Jeju-si, Jeju-do, Korea (33°32'2.58"N, 126°50'27.25"E), 15 Mar. 2017 ; male and 3 females (MABIK CR00248553), Deajin port, Hyeonnae-myeon , Goseong-gun, Gangwon-do, Korea (38°29'55.42"N, 128°25'35.53"E), 21 Jun. 2019 .

Etymology.

The new species is named in honor to Prof. Chang Bae Kim, an early amphipodologist of Korea, who collected and described the species firstly from Jeju, Korea in 1987.

Description.

Based on holotype male, 17.6 mm. Body (Figs 1 , 2 ) heavily covered with dark pigmentation spots creating bands on head, coxae, pereon, and pleon.

Head. Antenna 1 longer than antenna 2; peduncular article 1 subequal in length to article 2; article 2 longer than article 3 (2.3 times article 3); article 3 shorter than article 1 (0.5 times article 1).

Antenna 2 slender, similar to antenna 1; peduncular article 4 subequal in length to article 5; flagellum longer than peduncular article 5.

Upper lip with midlateral notch on margins.

Mandible molar well developed, triturating; palp apically setose, 3-articulate; mandibular palp article 1 shorter than article 2 (0.5 times article 2); article 2 shorter than article 3 (0.7 times article 3); article 3 longer than article 1 (3 times article 1).

Lower lip outer plates forming a medial excavation, lateral lobe slightly longer than medial lobe; mandibular lobe curved laterally, subacute apically.

Maxilla 1 inner plate with 1 slender seta; palp well developed, with apical robust setae.

Maxilla 2 inner plate narrower than outer plate, with oblique setal row.

Maxilliped outer plate with developed row of large robust setae along medial margin.

Pereon. Gnathopod 1 (Fig. 3A ) sexually dimorphic, smaller than gnathopod 2, carpus and propodus with numerous plumose setae on both anterior and posterior margins; coxa broader than deep, anterior margin slightly convex, anteroventral corner produced, rounded; basis longer than coxa, expanded anterodistally, anterodistal lobe large and subrounded; ischium anterior margin with small subrounded lobe; merus posterodistal corner subacute, produced; carpus about 2 times as long as broad, longer than propodus (1.3 times propodus), with posterodistal lobe slightly overlapping propodus, posterior margin slightly convex; 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 (Fig. 3B ) sexually dimorphic; basis longer than coxa, anterodistal lobe large and rounded, not reaching beyond ischium; ischium with anterior rounded lobe; carpus much shorter than propodus (0.4 times propodus), subtriangular; propodus narrow, 1.8 times as long as wide, subrectangular; palm transverse, with a sloped quadrate midmedial hump and an apically rounded tooth on posterodistal corner; dactylus slightly overreaching palm, curved, robust, apically blunt.

Pereopod 3 basis narrow; merus narrow; carpus about twice as long as broad.

Pereopod 4 basis similar to pereopod 3.

Pereopod 5 (Fig. 3C ) basis subovoid, without posterodistal lobe; merus subrectangular.

Pereopod 6 basis posterior margin rounded proximally, straight distally, with marginal robust setae; merus subrectangular.

Pereopod 7 (Fig. 3D ) similar to pereopod 6; basis with marginal robust setae.

Pleon. Epimera 1-3 with lateral ridges; epimera 2 and 3 subrounded posterodistally, with rounded tooth on each posteroventral angle. Epimeron 1 rounded posterodistally, with tooth on posteroventral angle; epimeron 2 ventral margin evenly curved; epimeron 3 ventral margin straight.

Uropod 1 reaching to end of uropod 2 rami; inner ramus longer than outer ramus; outer ramus slender, about 6 times as long as broad.

Uropod 2 inner ramus longer than outer ramus.

Uropod 3 (Fig. 3E ) peduncle much longer than broad (2.2 times as wide as long), 1.8 times as long as rami, 2 inner marginal robust setae, marginal slender setae present, with 7 distal peduncular robust setae; rami long, about twice as long as broad; outer ramus subequal in length to inner ramus, with 2 large recurved distal robust setae, and with 3 dorsomarginal robust setae, with lateral setal fringe; inner ramus with 4 distal robust setae, with 3 and 2 lateral robust setae on both inner and outer margins, respectively.

Telson (Fig. 3F ) subtriangular, apically rounded, with small apical cusps; with 3 groups of lateral plumose setae, and a pair row of setae on submedial margins.

Depth zone.

Littoral (1-2 m).

Distribution.

Jeju, East Sea of Korea, South Sea of Korea.

Remarks.

This species has been recognized as A. tarasovi in Korea since the species was described and illustrated by Shin et al. (2010). However, the type material of A. tarasovi described from Russia was examined here, and as a result, important morphological differences were detected between Korean material and the Russian type specimen. The characteristics differing between the Korean specimens and the type material are as follows. In male gnathopod 1, the basis is expanded anterodistally in the Korean specimens, while it is narrow and straight in the type material. The length ratios of carpus and propodus of the Korean and Russian specimens are 1.3 and 1.8, respectively. The shape of gnathopod 1 carpus is more rectangular in the Russian material than in the Korean sample. The propodus of male gnathopod 2 is longer and more rectangular in the Russian material compared to the Korean sample. The apical margin of the telson is round in the Korean specimen, while it is subacute in the Russian type material. Based on the morphological differences mentioned above, the Korean material has been assigned to a new species, A. changbaensis sp. nov.

Ampithoe changbaensis sp. nov. is similar to A. prolata Hughes & Peart, 2013; however, it can be distinguished from this species by the following characteristics: (1) presence of marginal setae on merus, carpus and propodus of male gnathopod 1; (2) swollen basis of male gnathopod 1; (3) subrectangular and trapezoid shape of propodus of male gnathopod 2; and (4) truncated posterior margin of carpus of female gnathopod 1.

Figures

Figure 1. Photograph of the Ampithoe changbaensis sp. nov., habitus of the male paratype. Scale bar: 5 mm. Photograph by Jin-Ho Park.

Figure 2. Ampithoe changbaensis sp. nov., male holotype. Habitus. Scale bar: 5 mm.

Figure 3. Ampithoe changbaensis sp. nov., male holotype A gnathopod 1 B gnathopod 2 C pereopod 5 D pereopod 7 E uropod 3 F telson. Scale bars: 2 mm (A-D); 0.25 mm (E, F).