Eoniphargus kojimai Ueno , 1955

Shintani, Aki, Lee, Chi-Woo & Tomikawa, Ko, 2022, Two new species add to the diversity of Eoniphargus in subterranean waters of Japan, with molecular phylogeny of the family Mesogammaridae (Crustacea, Amphipoda), Subterranean Biology 44, pp. 21-50 : 21

publication ID	https://dx.doi.org/10.3897/subtbiol.44.86914
publication LSID	lsid:zoobank.org:pub:1865B081-1072-4900-BFC7-563C0D29DA7D
persistent identifier	https://treatment.plazi.org/id/9D1D2179-706C-5BC4-BB2F-8F49983498F4
treatment provided by	Subterranean Biology by Pensoft
scientific name	Eoniphargus kojimai Ueno , 1955
status

Treatment

Eoniphargus kojimai Ueno, 1955

Figs 9 View Figure 9 , 10 View Figure 10 , 11 View Figure 11 , 12 Japanese name: Kojima-chikayokoebi View Figure 12

Neoniphargus (Eoniphargus) kojimai Uéno, 1955: 148, figs 1-3.

Eoniphargus kojimai : Straškraba, 1964, 138; Straškraba 1967, 127; Bousfield 1977, 301; Barnard and Barnard 1983, 581.

Material examined.

♀ 6.3 mm (NSMT-Cr 30785, G1905), ♂ 4.8 mm (NSMT-Cr 30786), Mamashita Spring (35.680066°N, 139.428283°E), Kunitachi, Tokyo, Japan, collected by K. Tomikawa on 25 June 2016 GoogleMaps . ♀ 5.0 mm (NSMT-Cr 30787, G 1930), ♀ 4.5 mm (NSMT-Cr 30788, G 1931), Hinochūōtoshokan Spring (35.655783°N, 139.382133°E), Hino, Tokyo, Japan, collected by K. Tomikawa on 25 June 2016 GoogleMaps .

Diagnosis.

Urosomite 3 with dorsal robust setae. Epimeral plates 2-3 each with ventral robust seta. Peduncular article 1 of antenna 1 with robust seta on posterodistal corner. Antenna 2 with peduncular article 2 gland cone not exceeding end of article 3; calceoli present in male. Mandible with 5- or 6-dentate left incisor; 4- or 5-dentate left lacinia mobilis, right one bifid with many teeth. Inner plate of maxilla 1 with eight plumose setae. Inner plate of maxilla 2 with nine facial seta in oblique row. Peduncle of pleopod 3 without seta. Uropod 1 with peduncle bearing basofacial robust setae. Uropod 3 with inner ramus 0.25 times as long as outer ramus in female and 0.27 times in male; outer ramus 2-ariticulate, with plumose setae on medial margin. Telson length 0.9 times width, cleft for 69% of length.

Description.

Female (NSMT-Cr 30785). Head (Fig. 9A View Figure 9 ) as long as pereonites 1 and 2 combined; eyes absent; inferior antennal sinus distinct with rounded angle. Dorsal margins of pleonites 1-3 (Fig. 9B-D View Figure 9 ) each with 4 setae. Posterodistal corners of epimeral plates 1-3 (Fig. 9E-G View Figure 9 ) weakly produced; ventral margin of epimeral plate 1 without setae, epimeral plates 2 and 3 each with ventral robust seta; posterior margins of epimeral plates 1-3 each with two setae. Dorsal margin of urosomite 1 (Fig. 9H View Figure 9 ) with slender setae and robust seta; urosomites 2 and 3 (Fig. 9I, J View Figure 9 ) with pair of dorsal robust setae.

Antenna 1 (Fig. 9K View Figure 9 ) length 0.22 times as long as body; length ratio of peduncular articles 1-3 in 1.0: 0.8: 0.4; posterodistal corner of peduncular article 1 with robust seta; accessory flagellum 4-articulate; primary flagellum 26-articulate. Antenna 2 (Fig. 9L View Figure 9 ) length 0.6 times as long as antenna 1; peduncular article 4 length 0.9 times as long as article 5; flagellum 13-articulate; calceoli absent.

Upper lip (Fig. 9M View Figure 9 ) with rounded apical margin bearing fine setae. Mandibles (Fig. 9N-P View Figure 9 ) with left and right incisors comprising five and six teeth, respectively; left lacinia mobilis comprising four teeth, right lacinia mobilis bifid with many teeth; molar process triturative with plumose seta; length ratio of palp articles 1-3 in 1.0: 2.3: 1.7; palp article 1 without setae; palp article 2 with nine marginal setae; palp article 3 with pair of A-setae, several D-setae and three E-setae, lateral face with fine setae. Lower lip (Fig. 9Q View Figure 9 ) lacking inner lobes; outer lobes broad, shoulder rounded, with fine setae. Maxilla 1 (Fig. 9R, S View Figure 9 ) with subtriangular inner lobe, bearing eight plumose setae on medial margin; outer plate rectangular, with 11 serrate robust setae apically; palp 2-articulate, article 1 without setae, article 2 with three robust setae and slender plumose seta along apically to medial margins. Maxilla 2 (Fig. 9T View Figure 9 ) with inner plate bearing nine plumose setae in oblique row. Maxilliped (Fig. 10A-C View Figure 10 ) with inner plate exceeding end of palp article 1, subquadrate, bearing three subapical robust setae and medial robust seta; outer plate ovate, reaching middle of palp article 2, with row of robust setae along apical to medial margins; palp 4-articulate, article 2 longest with medial setae, nail of article 4 distinct.

Gnathopod 1 (Fig. 10D, E View Figure 10 ) with subquadrate coxa bearing setae along anterior to ventral margins; anterior and posterior margins of basis with long setae; carpus length 1.1 times as long as length of propodus and 1.7 times width of carpus; propodus length 1.9 times width, palmar margin weakly serrate, oblique, with three medial and two lateral robust setae; dactylus almost reaching posterodistal corner of propodus. Gnathopod 2 (Fig. 10F, G View Figure 10 ) with coxa expanded proximally bearing setae along anterior to ventral margins; posterior margin of basis with long setae; carpus length 1.2 times as long as length of propodus and 3.3 times width of carpus; propodus length 2.8 times width, palmar margin weakly serrate, almost vertical, with two medial and one lateral robust setae; dactylus reaching posterodistal corner of propodus.

Pereopod 3 (Fig. 10H, I View Figure 10 ) with subquadrate coxa, proximally expanded, bearing setae along anterior to ventral margins; anteroproximal and posterior margins of basis with long setae. Pereopod 4 (Fig. 10J View Figure 10 ) with coxa bearing setae along anterior to ventral margins, posteroproximally concave; anteroproximal and posterior margins of basis with long setae. Pereopod 5 (Fig. 10K View Figure 10 ) with bilobed coxa bearing seta on anterior and posterior lobes; anterior margin of basis with robust setae, posterodistal corner weakly lobate. Pereopod 6 (Fig. 11A View Figure 11 ) with bilobed coxa bearing two setae on posterior lobe; basis with robust setae on anterior margin, posterodistal corner weakly lobate. Pereopod 7 (Fig. 11B View Figure 11 ) with elliptical basis bearing robust setae on anterior margin, posterodistal corner weakly lobate.

Coxal gills (Fig. 11G View Figure 11 ) ovate with stalks on gnathopod 2 and pereopods 3-6.

Pleopods 1-3 (Fig. 11C-F View Figure 11 ) with peduncles longer than rami, bearing distal seta on pleopod 1; retinacula paired (Fig. 11D View Figure 11 ); mediobasal margin of inner ramus with bifid plumose setae; rami well developed.

Uropod 1 (Fig. 11I View Figure 11 ) with peduncle bearing three basofacial robust setae and dorsal robust setae; inner ramus length 0.6 times as long as peduncle, with two medial robust setae and two ventroproximal setae; outer ramus length 0.9 times as long as inner ramus, with two medial and one lateral robust setae. Uropod 2 (Fig. 11J View Figure 11 ) with peduncle bearing dorsal robust setae; inner ramus as long as peduncle, bearing two medial and one lateral robust setae; outer ramus length 0.7 times as long as inner ramus, with lateral robust seta. Uropod 3 (Fig. 11K View Figure 11 ) with peduncle length 0.3 times as long as outer ramus, bearing robust setae on distal edge; inner ramus length 0.3 times as long as outer ramus, with seta on medial margin; outer ramus 2-articulate, proximal article with plumose setae on medial margin and robust setae on medial and lateral margins, terminal article length 0.2 times as long as proximal article with subapical setae.

Telson (Fig. 11L View Figure 11 ) length slightly shorter than width, each lobe with two lateral and three apical robust setae, and two dorsolateral and 1 subapical penicillate setae, cleft for 69%.

Male (NSMT-Cr 30786). Antenna 1 (Fig. 12A View Figure 12 ) length 0.24 times as long as body length; accessory flagellum 3-articulate; primary flagellum 25-articulate. Antenna 2 (Fig. 12B View Figure 12 ) length 0.6 times as long as antenna 1; peduncular article 4 length 0.8 times as long as peduncular article 5; peduncular article 5 and flagellum with calceoli (Fig. 12C View Figure 12 ); flagellum 16-articulate. Gnathopod 1 (Fig. 12D, E View Figure 12 ) with carpus length 1.2 times as long as length of propodus and 1.6 times width of carpus; propodus length 1.5 times width. Gnathopod 2 (Fig. 12F, G View Figure 12 ) with carpus length 1.1 times as long as length of propodus and 2.3 times width of carpus; propodus length 2.2 times width, palmar margin with two medial and two lateral robust setae. Uropod 3 (Fig. 12H View Figure 12 ) with peduncle length 0.4 times as long as outer ramus, peduncle bearing bent robust setae on distal edge.

Distribution and environment.

This species has been found in interstitial waters in Tokyo: the sand-filter bed of the Komae Purification Plant near the Tama River ( Uéno 1955); two springs - Mamashita Spring, Kunitachi and Hinochūōtoshokan Spring, Hino (this study).

Remarks.

The present specimens conform with the original description of E. kojimai by Uéno (1955). However, our specimens differed from the original description in the left mandible with 4-dentate lacinia mobilis and maxilla 1 with 11 serrate robust setae on the outer plate, which was 6-dentate incisor and 5-dentate lacinia mobilis of the left mandible, and 10 serrate robust setae in Uéno’s (1955) description. The exact number of these setae is difficult to ascertain because they are minute and overlap. This suggests that he may have misstated the number of setae. Unfortunately, the type specimen of this species is believed to be lost ( Tomikawa et al. 2007), so the character could not be verified. Examination of the present material from Kunitachi and Hino, Tokyo revealed some features that were not mentioned in the original description: maxilla 2 with inner plate bearing nine plumose setae in oblique row, uropod 1 peduncle with facial robust setae, and maxilliped inner plate with three subapical robust setae and medial robust seta.