Parapolycope oligohalina, Tanaka, Hayato & Tsukagoshi, Akira, 2010

Tanaka, Hayato & Tsukagoshi, Akira, 2010, Two new interstitial species of the genus Parapolycope (Crustacea: Ostracoda) from central Japan, Zootaxa 2500, pp. 39-57 : 41-48

publication ID	https://doi.org/ 10.5281/zenodo.195811
DOI	https://doi.org/10.5281/zenodo.6210178
persistent identifier	https://treatment.plazi.org/id/03B887C5-0A0D-5B34-FF3E-285920E16411
treatment provided by	Plazi
scientific name	Parapolycope oligohalina
status	sp. nov.

Treatment

Parapolycope oligohalina View in CoL sp. nov.

( Figs 2–7 View FIGURE 2 View FIGURE 3 View FIGURE 4 View FIGURE 5 View FIGURE 6 View FIGURE 7 )

Type series. All specimens collected at mouth of Kanogawa River ( Fig. 1 View FIGURE 1 C), Pacific coast of central Japan, 35°04'52"N, 138°51'33"E, on April 8th, 2007. Holotype: adult male (SUM-CO-1765), right valve length 0.22 mm, height 0.17 mm, left valve length 0.21 mm, height 0.15 mm, appendages mounted on slide and valves preserved in a cardboard cell slide, Paratypes: seven adult males (SUM-CO-1766, SUM-CO-1767, SUM-CO- 1768, SUM-CO-1769, SUM-CO-1775, SUM-CO-1776, SUM-CO-1777) and eight adult females (SUM-CO- 1770, SUM-CO-1771, SUM-CO-1772, SUM-CO-1773, SUM-CO-1774, SUM-CO-1778, SUM-CO-1779, SUM-CO-1780).

Etymology. Greek “oligo” and “haline” meaning “few” and “salty” respectively, referring to low salinity type environment of locality.

Occurrences. The mouth of Kanogawa River (Shizuoka Prefecture, type locality, medium sand), the mouth of Fujikawa River (Shizuoka Prefecture, 35°06'57"N, 138°38'25"E, medium sand, on April 14th, 2006), and the mouth of Okitsugawa River (Shizuoka Prefecture, 35°03'24"N, 138°32'05"E, medium sand, on August 21st, 2009). All specimens were collected from interstitial pore water.

Dimensions. See Table 1.

Diagnosis. Carapace slightly elliptical in lateral view. Carapace surface covered with puncta of varying size; coarse in middorsal to dorsal areas, fine in anteromedian, mid-anterior, and posterior areas. Length of male right valve 0.22–0.24 mm and left valve 0.21–0.24 mm, of female right valve 0.23–0.25 mm and left valve 0.23–0.24 mm. Serration along anteroventral margin: 11 sharp processes increasing in size toward ventral in right valve. Six claws on each furcal lamella. Male copulatory organ consisting of a curved short tube.

Description of adult male. Carapace ( Figs 2 View FIGURE 2 A–E, 3, 4). Oval in lateral view. Anteroventral margin of right valve with 11 sharp processes increasing in size to ventral, but absent in left valve. Marginal infold of each valve developing along anterodorsal to posteroventral margin. In right valve with ridgeline and wide groove, anteroventral groove with wrinkle, and one socket (part of hinge structure) forming dorsal end. In left valve with anterior thin groove and one knob (part of hinge structure) forming dorsal end. Right valve overlapping left valve along almost whole margin. External surface covered with circular puncta of varying size; coarse in middorsal to dorsomedian areas, fine in anteromedian, midanterior, and posterior areas. These puncta showing individual variation. Hinge structure consisting of one posterior element with jut and teeth, median element with a lot of fine and thin teeth in left valve, and posterior element with groove in right valve. Adductor muscle scars oval, consisting of three close scars.

Frontal organ. Absent.

Antennula ( Fig. 5 View FIGURE 5 C). Uniramus, four articulated podomeres. First podomere rectangular, with two and one tufts of setulae on anterior margin and lateral surface, respectively. Second podomere almost of same size as first podomere, with one long setulous seta and setulae on anterior margin. Third podomere about two–thirds length of second podomere, with one short seta at anterodistal end and four posterodistal setae consisting of one seta with large disk-shaped sucker, one long seta curving at tip, and two slender setae of subequal length, respectively. Fourth podomere very small with two very long and two long and slender setae at distal end.

Antenna ( Fig. 5 View FIGURE 5 E, F). Typically biramous with exopodite and endopodite consisting of eight and three podomeres, respectively. Exopodite: first podomere one–third length of basal podomere; second to seventh podomeres small, each with one very long seta at posterior end; eighth podomere very small, with one very long, two long, and one very short setae at distal end. Endopodite: first and second podomeres almost same length as first podomere of exopodite; second podomere widened distally, with three setae of different lengths along dorsal margin and six setae at distal end consisting of one short, two medium, three long; third podomere less than half length of second podomere, with one strong, hook-shaped seta extending backward, and three distal setae (one short and two long).

Mandibula ( Fig. 6 View FIGURE 6 A, B). Coxal endite with five teeth. Basis with three plumose setae on ventral margin. Exopodite absent. Endopodite consisting of two podomeres. First podomere with one plumose seta on ventral margin near proximal end and two long setulous setae on dorsal margin near distal end. Second podomere very small, bearing one setulous seta on ventral margin, one stout distal seta with setulae, and one bunch of setae at distal end.

Maxillula ( Fig. 6 View FIGURE 6 C). Precoxal endites with seven short setulous setae of different lengths. Coxal endites with two short plumose setae on medial surface near ventral margin, and three long plumose setae increasing in length distally on ventral margin. Basis and first podomere of endopodite fused. Basis with setulae on dorsal margin, and one long and one medium plumose seta on ventral margin. First podomere of endopodite with one short seta at dorsodistal end, and one short and two long setae on ventral margin. Second podomere small, with four setae consisting of one long with setulae, two long stout with bilateral spines at about one– third length from proximal end, and one long. Exopodite consisting of two podomeres. First podomere of exopodite with tuft of setulae on dorsal margin. Second podomere with tuft of setulae on dorsodistal margin, two slender, medium setae on ventral margin, and six setae consisting of two stout very long, two slender medium, and one short at distal end.

Fifth limb ( Fig. 6 View FIGURE 6 D, E). Coxa bearing branchial plate (epipodite) with ten long plumose setae and two short setulous setae on dorsal margin. Basis, endopodite, and exopodite fused. Basis with three long plumose setae on dorsal margin, one long stout setulous seta on ventral margin. Endopodite with two setulous setae on distal end. Exopodite with one stout setulous seta at distal end.

Furca ( Fig. 7 View FIGURE 7 A). Each lamella with six strong claws increasing in size towards anterior.

Male copulatory organ ( Fig. 7 View FIGURE 7 A). Arising from ventral outer surface of body at left side of terminal trunk segment and consisting of a curved short tube.

Upper lip ( Fig. 5 View FIGURE 5 A). Lobe with thumb-like process distally.

Description of adult female. Carapace ( Fig. 2 View FIGURE 2 F–J), mandibula, maxillula, fifth limbs, and furca ( Fig. 7 View FIGURE 7 B) similar to those of adult male.

Antennula ( Fig. 5 View FIGURE 5 D). Uniramus, four articulated podomeres. First podomere trapezoidal, with setulae on anterior part. Second podomere almost similar shape to first podomere, with one long seta and setulae on anterior margin, a few rows of fine setae on central surface, a few tufts of fine setae on distal part. Third podomere about half length of second podomere with one short seta at anterodistal end and one short seta at posterodistal end. Fourth podomere small, with five long setae.

Antenna ( Fig. 5 View FIGURE 5 G). Only endopodite different from that of adult male. Endopodite consisting of three podomeres. First podomere bare. Second podomere widened distally, with one seta at anterodistal end and six setae at posterodistal end. Third podomere about one–third length of second podomere, with one short and two long at distal end.

Upper lip ( Fig. 5 View FIGURE 5 B). Sub-semicircular.