Podoceropsis Boeck, 1816

Jung, Tae Won, Choi, Hyun Ki, Kim, Min-Seop & Yoon, Seong Myeong, 2017, Two new species of amphipods (Crustacea: Amphipoda: Photidae) from Korean waters with a redescription of Gammaropsis longipropodi, Zootaxa 4300 (3), pp. 380-402 : 394-401

Genus Podoceropsis Boeck, 1816

(Korean Name: Jjalb-eun-bu-chae-jjik-yeop-sae-u-sok, new)

Podoceropsis clavapes sp. nov.

(Korean Name: Keun-son-jjalb-eun-bu-chae-jjik-yeop-sae-u, new) ( Figures. 8–11 )

Type locality. Somaemuldo Island (35°37′32″N, 128°33′15″E), Maejuk-ri Hansan-myeon Tongyeong-si Gyeongsangnam-do South Korea.

Material examined. Holotype: male (NIBRIV398286), allotype: female (NIBRIV325715), and paratype: one male (NIBRIV325858); dissected appendages of types are mounted on permanent slide glasses and remain bodies are preserved in 99% ethanol; collected from type locality at 27 Sep. 2009, SCUBA diving (17 m depth), by T.W. Jung.

Etymology. The composite epithet of the specific name, clavapes , is a combination of the Latin clava and pes. This name means ‘clavate shaped foot’ referring to the shape of the propodus on gnathopod 2 in males.

Description. Holotype, male. Body about 2.7 mm long.

Head ( Fig. 8 A) rostrum minute; anterior cephalic lobe subtriangular, slightly dilated ventrally; eyes oval, lenticular, occupying most region of anterior cephalic lobe; inferior antennal sinus deep.

Antenna 1 ( Fig. 8 A, B) setose with single or paired setae posteriorly, with peduncular articles 1–3 in length ratio of 1:1.3:0.8; peduncular article 1 stout, with a stout seta at posterodistal corner; peduncular articles 2–3 slender; accessory flagellum minute, reduced triangular, with two minute setae; flagellum 12-articulate, each article with a group of aesthetasc and a pair of elongate or short serrate setae alternatively at posterodistal corner, distal article reduced.

Antenna 2 ( Fig. 8 A) slightly longer than antenna 2; gland cone not produced; with peduncular articles 3–5 in length ratio of 1:1.9:1.9, setose with single or paired setae posteriorly; peduncular article 3 stout, beyond apex of anterior cephalic lobe; peduncular article 4 slightly dilated distally, with a stout seta at anterodistal corner; flagellum 14-articulate, 2nd, 4th, 6th articles with a pair of long serrate setae, others with short setae distally.

Upper lip ( Fig. 8 C) subhexagonal, round and covered with minute setae apically; epistome produced.

Lower lip ( Fig. 8 D) inner lobe ovoid, with minute setae on apical margin; outer lobe swollen apically with minute setae, mandibular process produced.

Right mandible ( Fig. 8 G) with 5-dentate incisor (three large and two small) and 4-dentate lacinia mobilis, accessory setal row with seven dentate setae; molar triturative; palp robust, 3-articulate; article 1 shortest; article 2 stout, with three pappose and one pair of long setae medially and three long setae laterally, with two simple setae on surface; article 3 clavate, 0.8x length of article 2, with four pappose setae medially and a group of three setae laterally, apex obliquely blunt with several weakly plumose and simple setae.

Left mandible ( Fig. 8 H) with 5-dentate incisor and 4-dentate lacinia mobilis; accessory setal row with one plumose and eight dentate setae.

Maxilla 1 ( Fig. 8 E) inner plate subtriangular with a seta subapically; outer plate subrectangular, lined with nine dentate setae on apex; palp bi-articulate, slightly curved, apex of article 2 blunt with five dentate setae distally and four simple setae subdistally.

Maxilla 2 ( Fig. 8 F) inner plate subovoid with several setae apically, with an oblique row of setae on medial surface; outer plate slightly larger than inner plate, lined with marginal and submarginal setae apically.

Maxilliped ( Fig. 8 I) inner plate subrectangular, with three stout setae and several plumose setae on apex, and with a stout seta and a plumose seta on medial margin subdistally, lined with minute setae and with four plumose setae distally on lateral margin; outer plate elongate rectangular, with nine dentate setae arranged from distal 2/3 of medial margin to apex; palp 4-articulate; article 2 longest, swollen, lined with several long setae on medial margin; article 3 slightly dilated distally, with several setae on distal surface and corners; article 4 falcate, shorter than article 2, with four setae on distal 1/3 of medial margin, apical stout seta as long as palp article 3.

Gnathopod 1 ( Figs. 8 A, 9A) coxa sublozenge, expanded anteroventrally, lined with minute setae on anteroventral and ventral margins; basis subtrapezoidal, drastically increasing in width proximally and somewhat curved forward, anterodistal lobe weak with two minute setae; ischium with moderate anterior lobe and a pair of unequal setae at posterodistal corner; merus longer than ischium, convex posteriorly and acutely produced distally, with a distal row of several setae on posterior margin; carpus elongate, as long as basis, weakly lobate posterodistally, with three setae on anterior margin and one seta at anterodistal corner, with four groups of setae arranged on posterior margin and a group of three setae at posterodistal corner, with six setae on medial surface; propodus slender, 0.8x length of carpus, convex proximally and gradually diminished distally, with a minute seta and two groups of pappose and simple setae on anterior margin, with a group of three setae at anterodistal corner, with three groups of simple setae on posterior margin, palm indistinct and weakly pectinate distally; dactylus elongate, 0.6x length of propodus, lined with comb-like small teeth and several acute protrusions on inner margin.

Gnathopod 2 ( Fig. 9 B, C) coxa wider than long, produced anteroventrally and dilated downward at posteroventral margin, with two anterior and one posterior setae on ventral margin; basis slender, slightly curved, gradually wider distally, with developed anterodistal lobe bearing three setae, with a seta at posterodistal corner; ischium with an moderate anterior lobe and a seta at posterodistal corner; merus longer than ischium, posterior margin convex and produced distally with one and two setae subdistally; carpus robust, drastically widening distally, with a seta at anterodistal corner, posterodistal corner round with a pair of setae; propodus enlarged, stout, 1.5x length of basis, margins subparallel, anterior margin round at distal 1/4 and with a group of seven setae at anterodistal corner, posterior margin straight with four groups of elongate setae, with small and enlarged protrusions posterodistally, with three groups of setae on medial surface; palm indistinct with a group of eight facial setae; dactylus falcate, stout and enlarged, 0.8x length of propodus, with several acute small protrusions on inner margin.

Pereopod 3 ( Fig. 9 D, E) coxa subquadrate, convex anteriorly and ventrally, lined with seven minute setae on ventral margin; basis subtrapezoidal, straight, with two setae anteriorly and one seta at anterodistal corner, slightly widening posterodistally, with four long setae and with a distal seta on posterior margin; ischium with small anterior lobe; merus 0.6x length of basis, longest width as long as that of basis, anterior margin expanded distally with two long setae, produced distal corner with a pair of setae, posterior margin with four setae; carpus subrectangular, short, 0.3x length of merus, with two setae at anterodistal corner, with two seta on posterior margin and a group of four setae at posterodistal corner; propodus 0.5x length of basis, gradually diminished distally, anterior margin slightly convex with a seta and a group of three setae at anterodistal corner, posterior margin almost straight with three single and a pair of setae; dactylus falcate, 0.4x length of propodus.

Pereopod 4 ( Fig. 9 F, G) similar to pereopod 3 except for number and position of setae.

Pereopod 5 ( Fig. 10 A, B) coxa bilobate, anterior lobe larger than posterior lobe, expanded downward and round ventrally with five setae, posterior lobe with two setae posteroventrally, coxal gill elongate ovoid; basis with somewhat flattened at anterior margin presented by one simple and three stout setae, with a pair of stout and simple seta at anterodistal corner, posterior margin broadly expended, notched distally, weakly crenulate and lined with setae; ischium with a pair of setae anterodistally, posterior lobe small with a pair of setae; merus subrectangular, slightly twisted, widening distally, anterior margin convex with three minute setae and a group of two setae at anterodistal corner, posterior margin lined with four setae proximally and with weakly produced posterodistal corner bearing a pair of setae; carpus quadrate, widening, 0.6x length of merus, with a group of three setae at anterodistal corner and a group of two stout and two simple setae at posterodistal corner; propodus 1.1x length of carpus, slightly twisted, with a pair of unequal setae at anterodistal corner and a group of three long setae at posterodistal corner; dactylus also falcate and slightly twisted.

Pereopod 6 ( Fig. 10 C) slender; coxa bilobate, anterior lobe larger than posterior lobe, expanded downward with a seta anteroventrally, posterior lobe with two notches bearing a minute seta and with a stout spine at posteroventral corner, coxal gill similar to that of pereopod 5; basis moderate, with convex anterior margin presented by a spine, posterior margin slightly lobate with two minute setae and weakly angulate distally; ischium with a minute seta at anterodistal corner, posterior lobe small with a minute seta apically; merus slightly expanded distally, 0.7x length of basis, with a group of three setae at anterodistal corner, with two stout setae and a pair of stout and minute setae on posterior margin, with a pair of setae at weakly produced posterodistal corner; carpus rectangular, 0.6x length of merus, with a group of two setae at anterodistal corner and a group of three simple and two stout setae at posterodistal corner; propodus linear, not stout, 1.1x length of merus, with a pair of minute setae on anterior margin and a pair of simple and stout seta at anterodistal corner, with a minute seta and a pair of unequal setae on posterior margin and five setae at posterodistal corner; dactylus falcate, 0.5x length of propodus, with a plumose seta proximally and a minute seta subdistally on outer margin.

Pereopod 7 ( Fig. 10 D, E) shorter than pereopod 6; coxa unilobate, convex ventrally, with three plumose setae anteriorly, with two small notches bearing a minute seta at posteroventral corner; basis shorter and slightly wider than that of pereopod 6, with convex anterior margin presented by a stout seta, with a minute seta at anterodistal corner, posterior margin slightly lobate with two minute setae and weakly angulate proximal corner more expanded than that of pereopod 6, with a seta at oblique posterodistal corner; ischium with a minute seta at anterodistal corner, posterior lobe small; merus slightly expanded distally, 0.7x length of basis, with two minute setae on anterior margin and one seta at anterodistal corner, with two setae on posterior margin and a pair of setae at weakly produced posterodistal corner; carpus rectangular, 0.6x length of merus, without setae on anterior margin, with a group of three setae at anterodistal corner and a group of one stout and three simple setae at posterodistal corner; propodus linear, not stout, 1.3x length of merus, with two setae on anterior margin and a pair of simple and stout seta at anterodistal corner, with a minute seta and a group of three unequal setae on posterior margin and five setae at posterodistal corner; dactylus falcate, 0.4x length of propodus, with a plumose seta proximally and a minute seta subdistally on outer margin.

Pleonal epimera 1–3 ( Fig. 8 J) with a small notch bearing a minute seta at each posterodistal corner; epimeron 1 smallest, convex posteriorly; epimeron 2 subrectangular; epimeron 3 largest, convex and expanded backward posteriorly.

Pleopod 1 ( Fig. 11 A, B) peduncle rectangular, with one medial and three lateral setae, with a pair of retinaculae mediodistally; rami longer than peduncle, 11-articulate.

Pleopod 2 ( Fig. 11 C, D) similar to pleopod 1; inner and outer rami 10-articulate and 11-articulate, respectively.

Pleopod 3 ( Fig. 11 E, F) shortest; inner and outer rami 10-articulate and 12-articulate, respectively.

Uropod 1 ( Fig. 10 F) peduncle longer than rami, with nine lateral and five medial setae dorsally, inter-ramal process developed, 0.3x length of peduncle; inner ramus 0.7x length of peduncle, with two dorsolateral and four apical setae; outer ramus slightly longer than inner ramus, with two dorsomedial and four apical setae.

Uropod 2 ( Fig. 10 G) peduncle 0.6x length as long as that of uropod 1, with one lateral and two medial setae dorsally; inner ramus 0.8x length of peduncle with two lateral and two medial setae dorsally, drastically diminished distally and apex with a seta; outer ramus 1.4x length of inner ramus, with four dorsolateral and four apical setae.

Uropod 3 ( Fig. 10 I) short; peduncle slightly swollen, 0.8x length as long as that of uropod 2, with a laterodistal and a mediodistal seta dorsally; inner ramus shorter and slender than outer ramus, with two dorsomedial and one apical setae; outer ramus with one dorsomedial, two subapical and two apical setae.

Telson ( Fig. 10 H) trapezoidal, distal corner with four setae.

Allotype, female. Body about 2.4 mm long.

Gnathopod 1 ( Fig. 11 H, I) similar to that of male, except for deeper coxa.

Gnathopod 2 ( Fig. 11 J) coxa larger than that of male; basis not curved; propodus as long as basis, anterior margin convex with setae, palm excavate with stout defining spine and swollen protrusion bearing dentate margin located near hinge.

Pereopod 5 ( Fig. 11 G) posterodistal corner of basis not notched; merus not twisted.

Remarks. This new species can be readily assigned to genus Podoceropsis Boeck 1861 by the following characteristics: 1) the accessory flagellum of antenna 1 is uni-articulate and microscopic; 2) the shape of article 3 on mandibular palp is clavate; 3) the coxae are not deeper and without stridulation ridges; 4) the carpus of gnathopod 1 is not produced into a posterior lobe; 5) the stridulation ridges on the lateral surface of the basis on gnathopod 2 are absent; 6) the posteriordsital notch of the basis on pereopod 5 is present; 7) the inter-ramal process of the peduncle on uropod 1 is developed; and 8) the length of the rami on uropod 3 are subequal to each other and the inner ramus has one distal spine ( Conlan, 1983).

Podoceropsis clavapes sp. nov. shares same shape of elongate propodus on gnathopod 2 in mature males as P. angustimana Conlan, 1983 , P. liuruiyui ( Ren, 1992) , and P. ociosa ( J. L. Barnard, 1962) . However, the new species can be clearly distinguished from P. angustimana by the following characteristics: 1) the stout seta of peduncular article 1 posterodistally on antenna 1 is present (vs. absent in P. angustimana ); 2) article 3 of mandibular palp is distally slender than that of P. angustimana ; 3) proximal 4/5 of the anterior margin of the propodus on gnathopod 2 is straight and the distal 1/5 is sloped drastically in mature males (vs. convex in P. angustimana ); 4) the inner margin of the dactylus on gnathopod 2 is simpler in mature males (vs. slightly convex proximally in P. angustimana ); 5) the posterior margin of the basis on pereopod 5 is more expanded and weakly crenulated; 6) pereopod 6 is longer than pereopod 7 (vs. pereopod 6 is subsimilar to pereopod 7 in P. angustimana ); 7) each posterovnetral corner of pleonal epimer 1–3 has small notch with a minute seta (vs. absent in P. angustimana ); 8) the inter-ramal process of uropod 1 is 0.4x length of the inner ramus (vs. about 0.25x length of inner ramus in P. angustimana ); and 9) the peduncle of uropod 3 is longer than the rami (vs. the peduncle is shorter than the rami in P. angustimana ) ( Conlan, 1983).

This new species is different from P. liuruiyui by the following features: 1) article 3 of mandibular palp is distally slender than that of P. liuruiyui ; 2) the posterior margin of the propodus on gnathopod 2 is straight in mature males (vs. convex in P. liuruiyui ); 3) the palmer angle of gnathopod 2 has one large and one small protuberances in mature males (vs. only one small protuberance in P. liuruiyui ); 4) the posterior margin of the basis on pereopod 5 is weakly crenulated and lined with setae, while the distal notch is blunt in mature males (vs. that of P. liuruiyui is simple and bare, while the distal notch is more acute); 5) each posterovnetral corner of pleonal epimera 1–3 has a small notch having a minute seta (vs. absent in P. angustimana ); and 6) the posterior margin of telson is simple (vs. acutely produced in P. liuruiyui ) ( Ren, 1992).

Podoceropsis clavapes sp. nov. is quite different from P. ociosa by the following characteristics: 1) the defining seta of the propodus on ganthopod 1 is absent (vs. this seta is present in P. ociosa ); 2) apex of the dactylus on gnathopod 2 is not reaching the proximal margin of the propodus (vs. beyond the proximal margin of propodus in P. ociosa ); 3) the posterodistal notch of the basis on pereopod 5 is more expanded backward in P. ociosa ; and 4) each posterovnetral corner of pleonal epimer 1–3 has a small notch having a minute seta (vs. absent in P. ociosa ) ( Barnard, 1962).

Figures

FIGURE 8. Podoceropsis clavapes sp. nov., paratype, male 2.7 mm: A, head, antenna 1, 2 and coxa 1; B, accessory flagellum; C, upper lip; D, lower lip; E, maxilla 1; F, maxilla 2; G, right mandible; H, left mandible; I, maxilliped; J, pleonal epimera.

FIGURE 9. Podoceropsis clavapes sp. nov., paratype, male 2.7 mm: A, gnathopod 1; B, ganthopod 2; C, coxa 2; D, pereopod 3; E, coxa 3; F, pereopod 4; G, coxa 4 and gill of pereopod 4.

FIGURE 10. Podoceropsis clavapes sp. nov., paratype, male 2.7 mm: A, pereopod 5; B, coxa 5 and gill of pereopod 5; C, pereopod 6; D, pereopod 7; E, coxa 7; F, uropod 1; G, uropod 2; H, telson; I, uropod 3.

FIGURE 11. Podoceropsis clavapes sp. nov., paratype, male 2.7 mm (A – F) and paratype, female 2.4 mm (G – J): A, pleopod 1; B, retinaculae of pleopod 1; C, pleopod 2; D, retinaculae of pleopod 2; E, pleopod 3; F, retinaculae of pleopod 3. G, pereopod 5; H, ganthopod 1; I, coxa 1; J, gnathopod 2.