Leipsuropus hongi, Ariyama, Hiroyuki, 2012

Ariyama, Hiroyuki, 2012, Two new species of the genus Leipsuropus (Crustacea: Amphipoda: Podoceridae) from Japanese and Korean waters, Zootaxa 3485, pp. 41-55 : 50-53

Leipsuropus hongi sp. nov.

( Figs 1 B, 7–10)

Material examined. Holotype: male (OMNH-Ar-8947), 4.4 mm, off Jeju Island, East China Sea, 32°54'15"N, 126°05'41"E ( Fig. 1 B), 108 m deep, sediment type unknown, 2 June 2011, coll. C. S. Lee and W. H. Kim. Paratypes: 2 females (OMNH-Ar-8948, 8949), 3.7, 3.1 mm, same data as holotype.

Description. Male [holotype, 4.4 mm (OMNH-Ar-8947)]. Body ( Fig. 7 A, B), head with 1 blunt dorsal projection and 1 indistinct lateral projection on both sides, anteroventral corners pointed; pereonite 1 with 2 upward dorsal projections and 2 blunt lateral projections, ventral margins produced posterolaterally; pereonites 2, 3 each with 1 upward dorsal projection and 2 blunt lateral projections, ventral margins produced laterally; pereonites 4, 5 each with 1 backward dorsal projection and 2 blunt lateral projections, ventral margins produced laterally; pereonite 6 with 1 backward dorsal projection and 1 small lateral projection, ventral margins produced laterally; pereonites 6, 7 separated, pereonite 7 with 1 backward dorsal projection and 1 lateral projection, posteroventral corners produced; pleonites 1, 2 each with 1 upward dorsal projection and 1 lateral projection; pleonite 3 bare.

Antenna 1 ( Fig. 8 A), peduncular article 1 setose ventrally, lateral and medial surfaces with many fine setae; other parts lost. Antenna 2 ( Fig. 3 B, B1), peduncular article 3 bearing ventral long setae; other parts lost.

Mandible ( Fig. 8 D, D1, E, E1), left incisor with 6 cusps, right 5 cusps, left lacinia mobilis with 4 cusps, right 6 cusps, accessory blades 3 in left, 2 in right; plate-like structure with pectinate margin situated beside molar; palp article length ratio 1:2.3: 1.7 in left, 1:2.6: 1.8 in right, article 2 setose medially, article 3 setose mediodistally. Maxilla 1 ( Fig. 8 G, G1), outer plate with 8 robust setae distally; tip of palp article 2 bearing 7 robust setae. Maxilla 2 ( Fig. 8 H), medial margin of inner plate with several fine setae proximally. Maxilliped ( Fig. 8 I, I1), distal end of inner plate with 3 short robust setae, outer plate bearing 5 setulose setae and 9 robust setae.

Gnathopod 1 ( Fig. 9 A, A1–3), coxa projected anteriorly, lateral surface with several fine setae; basis widened distally, anterior and posterior margins with a few setae; posterodistal corner of ischium bearing long setae; posterior margins of merus and carpus with many long setae; propodus posterodistal corner with 7 small robust setae, anterodistal corner setose, medial surface bearing setulose and pectinate setae; dactylus short, curved, posterior margin with several denticles. Gnathopod 2 ( Fig. 9 B, B1), coxa short, ventral margin hollowed, gill curved anteriorly; basis widened distally, anterodistal corner acutely projected laterally, lateral and medial surfaces bearing many fine setae; distal end of ischium with lateral projection; posterodistal end of merus slightly pointed, posterodistal margin setose; carpus short, distal margin fringed with short setae; propodus broadened, anterior surface with 2 lateral and 8 medial thick setae, posterior margin with 1 wide and 2 triangular processes, posteromedial surface bearing long plumose setae densely; dactylus strongly curved posteriorly.

Pereopods, bases–dactyli lost. Coxa 3 ( Fig. 8 C) pentagonal, lateral surface with many fine setae; gill large, narrowed distally. Coxa 4 ( Fig. 8 D) wide, lateral surface with many fine setae; gill broad. Coxa 5 ( Fig. 8 E) lobate, anterolateral surface with many fine setae; gill broad. Coxa 6 ( Fig. 8 F) lobate, with several fine setae; gill small. Coxa 7 ( Fig. 8 G) lobate, with several fine setae.

Pleopod 1 ( Fig. 10 A, A1) shortest; peduncle long, with 5 short setae and 9 coupling hooks; outer ramus shorter than inner, outer and inner rami with 8 and 9 articles, respectively, article 1 of inner ramus swelled laterally. Pleopod 2 ( Fig. 10 B, B1) longer than pleopod 1; peduncle with many short setae and 8 coupling hooks; outer ramus slightly longer than inner, outer and inner rami with 10 and 9 articles, respectively. Pleopod 3 ( Fig. 10 C, C1) same length as pleopod 2; peduncle with many short setae and 7 coupling hooks; outer ramus slightly longer than inner, outer and inner rami with 11 and 10 articles, respectively. Uropod 1 ( Fig. 9 H), peduncle with 3 dorsolateral robust setae, medial surface bearing 3 setae; outer ramus 1.3 times as long as peduncle, with 6 dorsal and 2 terminal robust setae; inner ramus 1.7 times as long as outer ramus, with 3 dorsolateral, 4 dorsomedial and 4 terminal robust setae. Uropod 3 ( Fig. 9 I, J) curled, with 5 setae, distal margin fringed with short setae. Telson ( Fig. 9 I) broader than long, round, with a few ordinary setae and several fine setae.

Female [paratype, 3.7 mm (OMNH-Ar-8948)]. Generally similar to male except for gnathopod 2 and oostegites. Gnathopod 2 ( Fig. 10 D) smaller than that of male; basis with acute distal projection; distal end of ischium with lateral projection; posterodistal end of merus acutely pointed, with several setae; propodus roundish, anterior surface with 5 lateral and 5 medial thick setae, posterior margin with 1 process bearing robust seta, posteromedial surface with several long simple setae. Oostegites on coxae 2–4 ( Fig. 10 E–G) gradually wider, margins with many setae.

Coloration in preservative (holotype, male). Eyes yellow; pale brown pigment remained each on dorsal and lateral projections, coxae, peduncular article 1 of antenna 1, peduncular article 3 of antenna 2, and anterior margin of gnathopod 2 propodus.

Etymology. Dedicated to Prof. Jae-Sang Hong for donating the specimens.

Remarks. This new species is characterized by the dorsal and lateral projections and the setose male gnathopod 2 with sinuate palm. Similarly to Leipsuropus astericolus , L. hongi sp. nov. differs from L. parasiticus in (1) presence of the projections, (2) not fused pereonites 6, 7, (3) strongly curved dactylus of male gnathopod 2, and (4) oblique palm of female gnathopod 2. The dorsal projections of L. hongi closely resemble L. sinensis . But L. hongi can be distinguished from L. sinensis in having the sinuate palm of male gnathopod 2 and the telson without dorsal protuberance. Moreover, L. hongi is different from L. astericolus in the relatively blunt dorsal and lateral projections (acute in L. astericolus ), the male gnathopod 2 with dense plumose setae (non-dense simple setae in L. astericolus ), and the broader propodus of the female gnathopod 2.

Figures

FIGURE 1. Map showing the collecting sites of the described species. A: Leipsuropus astericolus sp. nov., B: L. hongi sp. nov.

FIGURE 3. Leipsuropus astericolus sp. nov. A, paratype, female (OMNH-Ar- 8945), 3.8 mm; B, D, E, G, H, holotype, female (OMNH-Ar- 8941), 3.2 mm; C, F, paratype, male (OMNH-Ar- 8942), 4.4 mm. A, right antenna 1, lateral view; A 1, accessory flagellum of right antenna 1, medial view; B, left antenna 2, lateral view; C, upper lip, anterolateral view; D, left mandible, medial view; D 1, incisor, lacinia mobilis and accessory blades of left mandible, medial view; E, right mandible, medial view; E 1, incisor, lacinia mobilis and accessory blades of right mandible, medial view; F, lower lip, ventral view; G, right maxilla 1, dorsal view; G 1, distal part of right maxilla 1, dorsal view; H, left maxilla 2, dorsal view. Scales: 0.05 mm.

FIGURE 7. Leipsuropus hongi sp. nov. Holotype, male (OMNH-Ar- 8947), 4.4 mm. A, habitus, lateral view; B, same, dorsal view (right half). Scale: 0.5 mm.

FIGURE 8. Leipsuropus hongi sp. nov. Holotype, male (OMNH-Ar- 8947), 4.4 mm. A, peduncular article 1 of left antenna 1, lateral view; B, peduncular articles 2, 3 of left antenna 2, lateral view; C, upper lip, posterolateral view; D, left mandible, medial view; D 1, incisor, lacinia mobilis and accessory blades of left mandible, medial view; E, right mandible, medial view; E 1, incisor, lacinia mobilis and accessory blades of right mandible, medial view; F, lower lip, ventral view; G, left maxilla 1, ventral view; G 1, distal part of left maxilla 1, ventral view; H, left maxilla 2, ventral view; I, maxilliped, ventral view; I 1, outer and inner plates of maxilliped, ventral view, ordinary setae omitted. Scales: 0.1 mm.

FIGURE 9. Leipsuropus hongi sp. nov. Holotype, male (OMNH-Ar- 8947), 4.4 mm. A, left gnathopod 1, lateral view; A 1, palm of left gnathopod 1, lateral view, ordinary setae omitted; A 2, A 3, medial setae of left gnathopod 1, lateral views; B, left gnathopod 2, lateral view; B 1, left gnathopod 2, medial view; B 2, medial seta of left gnathopod 2, lateral view; C – G, left coxae 3 – 7, lateral views; H, left uropod 1, lateral view; I, urosomites 2, 3, telson and uropods 3, dorsolateral view; J, right uropod 3, ventrolateral view. Scales: 0.1 mm.

FIGURE 10. Leipsuropus hongi sp. nov. A – C, holotype, male (OMNH-Ar- 8947), 4.4 mm; D – G, paratype, female (OMNH- Ar- 8948), 3.7 mm. A, left pleopod 1, anterior view; A 1, coupling hooks of left pleopod 1, anterior view; B, left pleopod 2, posterior view; B 1, coupling hooks of left pleopod 2, posterior view; C, left pleopod 3, posterior view; C 1, coupling hooks of left pleopod 3, posterior view; D, right gnathopod 2, lateral view, fine setae omitted; E – G, right oostegites on coxae 2 – 4, lateral views. Scales: 0.1 mm.