Paracobanocythere grandis Higashi & Tsukagoshi, 2011, sp. nov.
Creators: name: Higashi, Ryouichi
name: Tsukagoshi, Akira
Publisher: name: Zenodo
Year: 2011
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Ostracoda
Podocopida
Cobanocytheridae
Paracobanocythere
Paracobanocythere grandis

description: Paracobanocythere grandis sp. nov.
(Figs 15 B, 16–19)
Type series. Holotype: adult male (SUM-CO-2004), right valve length 484 µm, height 157 µm, left valve length 497 µm, height 166 µm, appendages mounted on slide and valves preserved in a cardboard cell slide, Paratypes: 11 adult males (SUM-CO- 2005–2015) and 7 adult females (SUM-CO- 2016–2022). All illustrated specimens were collected at the type locality on July 29, 2006.
Type locality. Mochimune, Shizuoka City, Shizuoka Prefecture, Pacific coast of central Japan (Fig. 1 B), 34°55'04"N, 138°21'43"E. Marine littoral beach; sediment composed of clastic coarse sand and granules. Sampling depth approximately 10 cm.
Etymology. The Latin grandis (large) refers to the large carapace size of this species.
Diagnosis. Male larger than female. Carapace rounded triangular in anterior view, and upside-down heart shaped in posterior view. Anterior margin rounded and antero-ventral margin concaved in lateral view. Posterior margin rounded forming a pointed distal tip with ventral margin. Sixty-four pore systems per valve. Six and three marginal pore along anterior and posterior margins, respectively. Two vein-like structures running forward on inner surface of anterior marginal infold. Rib developed behind adductor muscle scars. Male copulatory organ remarkably asymmetric between both hemipenes: right one consisting of round-tipped and fused distal lobe and tip of capsule; left one consisting of sharply round-tipped and curved distal lobe, and claw-like extended tip of capsule.
Description. Carapace (Figs 16 and 17). Depressed dorso-ventrally and elongated. Rounded triangular-shaped outline in anterior view and upside-down heart shaped outline in posterior view. External surface smooth. In lateral view, anterior margin rounded, antero-ventral margin concaved and posterior margins rounded forming a pointed distal tip with ventral margin. Ventral area flat. All pore systems simple type and 64 per valve. Marginal infold broad in anterior area and narrow in posterior area. Two vein-like structures running forward on inner surface of centre of anterior marginal infold. Vestibula occupying most area of marginal infold. Left valve overlapping right valve along anterior, posterior and mid-ventral margins. Hingement of adont type. Four adductor muscle scars in oblique row.
Antennula (Fig. 18 A). Five articulated podomeres. First podomere short, distorted trapezoid: thin framework extended along posterior margin. Second podomere five and half times as long as first podomere, with one medium seta on outside of distal end and long setulae along middle of anterior margin. Third podomere one-third as long as second podomere and bare. Fourth podomere three times as long as third podomere, with one very short seta on middle of anterior margin, one long and two medium setae on antero-distal end, one long seta on middle of posterior margin and one long seta on postero-distal end. Fifth podomere two-fifths as long as fourth podomere, with one very long, one long seta, and one pair of basally fused setae composed of slender and round-tipped setae on distal end, respectively.
Antenna (Fig. 18 B). Four articulated podomeres. First podomere with unclear three-segmented spinneret (exopodite) on outside distal end. Second podomere two-fifths as long as first podomere, with one medium seta on postero-distal end. Third podomere three times as long as second podomere, with one medium and one short setae on antero-medial suture, one medium seta on middle of posterior margin and one short seta on postero-distal end. Fourth podomere one-fifth as long as third podomere, with setulous-tipped claw on antero-distal end and one short and one thick setae on postero-distal end.
Mandibula (Fig. 18 C). Coxal plate long, with one thick seta on antero-ventral part, two setae between first and second anterior coxal endites, and one seta between third and fourth anterior coxal endites. Seven coxal endites. Palp consisting of four articulated podomeres. First podomere with very long and setulous seta (exopodite) on outside proximal end and one medium seta on ventro-distal end. Second podomere five-fourths as long as first podomere, with one long seta on ventro-distal end. Third podomere two-thirds as long as second podomere, with two very long and setulous and one long and setulous setae on middle of dorsal margin, two long setae on ventro-distal end and one long seta on inside distal end. Fourth podomere one-third as long as third podomere, with one very long and two long setae on distal end.
Maxillula (Fig. 18 D). Thin branchial plate (exopodite) with ten setae. Basal podomere with one palp and three endites. Palp consisting of two indistinct podomeres: first podomere with three long setae on dorso-distal end and three long setae on ventro-distal end; second podomere as long as first podomere, with two long setae on distal end. Endites: dorsal one with six setae; middle one with five setae, and ventral one with four setae.
Fifth limb (Fig. 18 E). Four articulated podomeres. First podomere with one medium seta on antero-distal end and long seta on postero-proximal part. Second podomere four-thirds as long as first podomere, with one medium seta on antero-distal end. Bare third podomere two-fifths as long as second podomere. Fourth podomere six-fifths as long as second podomere, with setulae along middle of anterior margin and stout claw on distal end.
Sixth limb (Fig. 18 F, G). Remarkably reduced leg in male (Fig. 18 G): three articulated podomeres; first podomere with one medium seta on antero-proximal part, one short seta on antero-distal end, one medium and setulous seta on middle of postero-proximal part and setulae along postero-proximal margin; second podomere nine-tenths as long as first podomere, with one long seta on antero-distal end; third podomere three-fifths as long as second podomere, with one setulous and undeveloped claw on distal end. Normal walking leg in female (Fig. 18 H): four articulated podomeres; first podomere with one medium seta on antero-distal end and one long seta on posteroproximal part; second podomere four-fifths as long as first podomere, with one very short seta on antero-distal end; third podomere three-sevenths as long as second podomere; fourth podomere three-halves as long as third podomere, with stout distal claw.
Seventh limb (Fig. 18 H, I). Four articulated podomeres. First podomere with one medium setulous seta on postero-proximal part and one short setulous seta on antero-distal end. Second podomere nine-eighths as long as first podomere, with one short seta on antero-distal end. Third podomere one-third as long as second podomere with short setulae distally along one-third of anterior margin. Fourth podomere five-thirds as long as third podomere, with one stout distal claw and setulae along antero-distal margin. Distal claw sexual dimorphic: in male (Fig. 18 H), thick with two short stout spines on antero-proximal part, hook-shaped structure developing on distal end, one very short seta on posterior part near hook-shaped structure and setulae along antero-distal margin to proximal part of hook-shaped structure; in female (Fig. 18 I), only with setulae distally along two-thirds of anterior margin.
Male brush-shaped organ (Fig. 18 J). Consisting of two branches, each branch with about 16 setae on distal margin.
Male copulatory organ (Fig. 19A, B). Capsule of both hemipenes trapezoidal. Flexible copulatory duct (Cd) extremely long, more than five times of length of capsule. Tip of capsule (Tc) and distal lobe (Dl) remarkably asymmetric in right and left hemipenes. Right hemipenis (Fig. 19A): Tc and Dl fused and round-tipped. Left hemipenis (Fig. 19B): Tc strongly sclerotised, claw-shaped and ventrally curved; Dl slender, ventrally curved at distal third, and round-tipped.
Caudal part of female (Fig. 15 B). Genitalia consisting of sclerotised frame-work connected to round structure and pouch with very long duct. Caudal rami near genitalia, with one seta. One seta posteriorly near caudal rami. Caudal process very small.
Eye. Absent.
Dimensions. See Table 4.
Length (µm) Height (µm)
Mean Observed range N Mean Observed range N Male Right valve 491 481–503 5 160 157–165 5 Left valve 508 497–519 4 170 166–175 4 Female Right valve 464 457–471 5 154 151–158 5 Left valve 478 466–486 5 166 162–171 5
Occurrence. So far known only from type locality.
Remarks. Paracobanocythere grandis sp. nov. has some unique characters compared with its congeners, i.e. Paracobanocythere hawaiiensis and P. watanabei sp. nov. The sexual dimorphism of the distal claw of the seventh limb is so far observed in only P. grandis sp. nov. The proximal spines and hook-shaped structure might play a role in mating behaviour of male, e.g. clasping female or giving physical stimulus to female. This new species is also characterised by the extremely long Cd of male copulatory organ.
description: Published as part of Higashi, Ryouichi & Tsukagoshi, Akira, 2011, Four new species of the interstitial family Cobanocytheridae (Crustacea: Ostracoda) from central Japan, pp. 33-56 in Zootaxa 2924 on pages 50-54, DOI: 10.5281/zenodo.207881