Parasterope sagami, Pham & Karanovic, 2022

Pham, Huyen T. M. & Karanovic, Ivana, 2022, Four new Parasterope (Ostracoda, Myodocopina) from the Northwest Pacific and their phylogeny based on 16 S rRNA, ZooKeys 1095, pp. 13-42 : 13

Parasterope sagami sp. nov.

Figs 5 , 6 , 7

Specimens examined.

Holotype female dissected on one slide, shells on SEM stub (NIBR IV0000890541). Paratypes: one male and one female dissected on separate slides, shells on SEM stub (NIBR IV0000890542). All from the type locality: Japan, Kanagawa, Sagami Bay (35°09.420'N, 139°36.556'E), 5 m, collected during 6thJAMBIO project on 13 February 2015 .

Etymology.

The species name was chosen after the Sagami Bay, from where the species was collected. It is an adjective agreeing with female gender of the genus.

Diagnosis.

Surface of the shell completely smooth. Posterior infold of the carapace with a broad shelf. Dorsal margin rounded in female and almost perpendicular in male. Lateral eye well developed with black pigmented ommatidia, smaller in female than in male. A1 8-segmented without d-bristle on the 8th joint. Uropodal lamellae with eight claws.

Description.

Female. Shell (Fig. 5a-c ). Carapace oval, broadening at posterior, greatest height near middle, carapace length 1.21 mm, height 0.83 mm. Carapace smooth and without ornamentation.

A1 (Fig. 6a ). 1st joint: with no hair on broad surface. 2nd joint: one spinous dorsal seta, no lateral bristle, and two dorsal spines on each side of dorsal margin. 3rd joint: seven setae: one short ventral and six dorsal. 4th joint: three setae (one long dorsal bristle and two short ventral bristle) and two small ventral spines. 5th joint: sensory bristle with six filaments without short proximal terminal. 6th joint: unidentified. 7th joint: a-bristle claw-like, bare; b-seta with marginal filaments; c-seta with marginal filaments. 8th joint: d-bristle absent; e-bristle bare, with blunt tip; f- bristle with marginal filaments; g-bristle with three filaments without proximal and marginal filament.

Bellonci orange (Fig. 7a ). Elongate with rounded tip, unclear constriction.

Eyes (Fig. 7a ). Lateral eye with 12 ommatidia obscured by black pigment; Medial eye rounded and pigmented.

A2 (Fig. 6b ). Protopodite: rounded without medial bristle. Endopodite: 3-jointed with long terminal bristle near junction between 2nd and 3rd join. Exopodite: 9-jointed; bristle of 2nd segment along ventral margin and spines along dorsal margin reaching 8th joint; 3rd-8th joints with natatory hairs and spines along proximal part of ventral margin. 9th article: four bristles (two long natatory and two short bristles). 1st-8th with minute spines at inner terminal corner.

Md (Fig. 6c ). Coxale endite: unable to determine. Basale endite with four spinous end bristles, three triaenid bristles with three pairs spines excluding terminal pair. Basale dorsal margin with three long terminal setae, without mid-bristle. Exopodite with hirsute tip and two small subterminal setae, exopodite length ~ ¾ of dorsal margin of first endopodite article. Endopodite: 1st joint: ventral margin with three bristles (one missing, one long with long marginal spines, and one shorter without spine or hair); 2nd joint: ventral margin: with three terminal bristles; dorsal margin: with stout a-, b-, c-, and d-bristles and one short bristle proximal to a-bristle; e-bristle missing, two medial bristles adjacent to b-bristle; three medial bristles forming an oblique row adjacent to c-bristle; f-bristle between c- and d-bristle, long, bare; g-bristle shorter than f-bristle. End segment with a strong dorsal claw-like bristle without marginal spines, three juxtaposed stout bristles of equal length.

Mxl (Fig. 7e ). Endite I with three bristles. Endite II with four bristles. Basale: one dorsal medial distal bristle, two ventral medial proximal bristles. Endopodite: 1st with one short α-seta and one hairy β-seta; 2nd article with two terminal bristles.

L5 (Fig. 7f ). Ventral section with fan of long setae. Comb: spinous exopodite bristle over past distal end of comb, one bristle just proximal at the ventral edge of comb.

L6 (Fig. 7g ). Anterior margin with one endite bristle. Ventral margin with two spinous anterior bristles separated by space from 13 bristles. Anterior, ventral, and posterior margins, and medial surfaces hirsute. Lateral flap spinous but without bristles.

L7 (Fig. 7h ). Each limb with 12 bristles. Six proximal and six distal bristles (three on each side).

F (Fig. 7i ). Each lamella with five claws and three posterior claws bristle-like. A total of eight claws and bristles.

Male. All features comparable to adult female; important differences are:

Shell (Fig. 5d-f ). Carapace more elongate than that of female and, carapace length 1.65 mm, height at middle 1.02 mm.

A1 (Fig. 7b ). Sensory seta with robust stem and many filaments. 7th and 8th joints with very long c- and f-setae (long as carapace length) each with numerous of marginal filaments. 2nd joint with lateral bristle. 2nd and 4th joints without dorsal margin spines.

Eyes. Lateral eye with 18 ommatidia obscured by black pigment.

A2 (Fig. 7c ). Endopodite with three articles, article two with two lateral setae, article three recurved with one small proximal seta.

Md (Fig. 7d ). Basale dorsal margin with two long terminal setae. Endopodite: 2nd joint: dorsal margin: with stout a-, b-bristles, c-and d-claws bristle-like, and two short bristles proximal to a-bristle; e-bristle present on male. Two oblique rows between b- and c-bristles (a row adjacent to b-bristle with four bristles, a row adjacent to c-claw bristle-like with six bristles).

Reproductive organs. Unknown.

Remarks.

Parasterope sagami differs from all other Parasterope representatives by the combination of the following characters:

Female. Dorsal margin of the Md basale has three long terminal setae next to the exopodite, and it has no mid-bristle. In addition, the A1 g-bristle has a peculiar shape, and there is no lateral bristle on the A1 2nd joint;

Male. The presence of the c- and d-claws bristle-like on the Md endopodite 2nd joint in the adult males is unique for the new species.

In addition to the above characters, P. sagami differs from P. busanensis and the morphology of the endite II of Mxl. Namely, the endite carries three rather than four bristles. Also, the short α-seta on the Mxl exopodite is absent in P. busanensis .

Parasterope jenseni was also described from Sagami Sea, Japan ( Poulsen 1965) and it also has no lateral bristle on the A1 2nd joint. It differs from P. sagami by having small lateral eyes with ~ 10 ommatidia; a long stem of the sensory bristle (~ 4 × the length of the 6th joint); and the presence of spines on the ventral margin of the protopodite of A2 ( Poulsen 1965).

Parasterope obesa Poulsen, 1965 from Misaki, Japan has a lateral bristle on the 2nd joint of A1 which is absent in the two above species; 4th joint of the A1 is without lateral spines on the ventral margin otherwise present in the new species; and there are more than ten bristles on the ventral edge of the comb.

GenBank numbers 16S: OK048683, OK048684; 18S: OK048721, OK048722.

Figures

Figure 5. Light microscopy and scanning electron microscopy images of Parasterope sagami sp. nov. a-c holotype female adult: a External view b Lateral view from right valve c Internal view from left valve. d-f paratype male adult: d External view e Lateral view from right valve f Internal view of left valve.

Figure 6. Parasterope sagami sp. nov. holotype female adult: a A 1 b A 2 c Md. Scale bar: 0.1 mm.

Figure 7. Parasterope sagami sp. nov. holotype male adult: a Bellonci organ e Mxl f L 5 g L 6 h L 7 i F. Paratype male adult: b A 1 c A 2 endopodite d Md. Scale bar: 0.1 mm.