Paracypria plumosa, Hiruta, Shimpei F. & Kakui, Keiichi, 2016

Hiruta, Shimpei F. & Kakui, Keiichi, 2016, Three new brackish-water thalassocypridine species (Crustacea: Ostracoda: Paracyprididae) from the Ryukyu Islands, southwestern Japan, Zootaxa 4169 (3), pp. 515-539 : 529-533

Paracypria plumosa sp. nov.

( Figures 13–16 )

Material examined. Holotype: ICHUM 4915 (male), 24°26′32″N, 124°8′21″E, Kabira Bay , Ishigaki Island, Okinawa , Japan, 28 March 2013, soft parts mounted on 10 slides, carapace mounted on a microfossil slide. Allotype: ICHUM 4920 (female), collection data same as for holotype, soft parts mounted on nine slides, carapace mounted on a microfossil slide . Paratypes (collection data same as for holotype): ICHUM 4916–4919 (males) and 4921–4923 (females), soft parts mounted on glass slides, carapaces mounted on microfossil slides; ICHUM 4926– 4928 (females), mounted on stubs for SEM observation; ICHUM 4924–4925 (females), exoskeleton and carapace after DNA extraction mounted on a glass slide.

Etymology. The new specific name is an adjective, Latin plumosa (plumose), referring to the plumed brushlike structure on the terminal claw of the mandibular palp and the largest tooth of the coxal plate.

Diagnosis. Carapace with maximum height anterior of mid-length, ventral margin straight, anterior margin broadly rounded, posterior margin sharply rounded. A1 with non-bulbous Rome organ. Terminal segment of Md palp with large brush-like claw fused to segment, coxal plate with fine setae on largest tooth forming comb-like structure. Male palp of L5 symmetrical, with 2 long one shorter rays protruding from palp. Female L5 with slender palp and very short h1–3 setae. Zenker organ with 5 internal rosettes. Hp small and rounded, distally with one round lobe. Uropodal ramus with small Sa, fine Sp1, longer Sp2 setae, and claws Ga and Gp with robust spines distally.

COI barcoding sequence. AB920555 (658 bp), from ICHUM 4924 (paratype).

Description of male. Carapace ( Figures 13 A, B; 14A) 0.57–0.60 mm long, 0.27–0.28 mm high (n = 4); 0.59 mm long, 0.27 mm high in holotype; elongate in lateral view, maximum height anterior of mid-length, broadly rounded at anterior end, posterior margin sharply rounded, slightly concave ventrally; spindle-shaped in dorsal view, with maximum width anterior of mid-length. Valves transparent, with brownish epidermal pigment except around fused median eyes; fine setae present on smooth surface.

A1 ( Figure 14 B) seven-segmented. First two podomeres fused, with one dorsal and two long apico-ventral plumose setae. No Wouters organ present. Third podomere wider than long, with apico-dorsal seta, and Rome organ. Fourth podomere quadrate, with apico-dorsal seta. Fifth podomere quadrate, with one long apico-dorsal seta. Sixth podomere quadrate, with two long apico-dorsal and one apico-ventral setae. Seventh podomere with four long apical setae. Eighth podomere elongate, slender, with one long, one normal, and one short setae, and aesthetasc ya.

A2 ( Figure 14 C) five-segmented. First podomere (Pr) with one long, apico-ventral seta, one medium-long, antero-proximal seta, and one latero-proximal seta. Second podomere (EI) with two apico-ventral setae, aesthetasc Y, and Exo, which consists of one long and two short inconspicuous setae; 4 + 1 natatory setae extending to the tip of A2 terminal claw. Third podomere (EII) with two mid-apical male bristles (t2 and t3), one apico-ventral seta (t1), one stout apico-dorsal (t4) and one normal setae, and aesthetasc y2. Fourth podomere (EIII) with claws G1 short G2, z1 and z2, setae short z3, and one short apico-ventral seta. Fifth podomere (EIV) with GM and short, fine Gm, one apical seta, and aesthetasc y3.

Md ( Figure 14 E) consisting of coxal plate and four-segmented palp. Coxal plate with antero-lateral plumose seta and five stout teeth, latter interspersed with several setae of various lengths. Largest teeth with comb-like process ( Figures 13 D; 14E). Palp with smooth alpha seta; smooth, long gamma setae; and plumed, very short beta seta. First podomere with exopodal plate (Exo). Terminal podomere of palp fused with terminal claw to form distally plumed claw ( Figures 13 D; 14E); with two apical setae and one shorter apical seta.

Mx ( Figure 14 F) with elongate vibratory plate, three masticatory processes, and two-segmented palp.

L5 ( Figure 15 A, B) with palp, vibratory plate (Exo; not illustrated), one antero-proximal seta, one antero-apical seta, and one postero-apical seta. Vibratory plate with four filaments. Palp transformed into two-segmented clasping process; first segment with two long and one shorter apico-ventral filament-like rays; terminal segment stout, curved, with one terminal seta. Masticatory process with numerous setae.

L6 ( Figure 15 C) five-segmented. Fifth podomere with one long terminal claw (h2) and one short, one indistinct short fine setae (h1, h3).

L7 ( Figure 15 D) four-segmented. Penultimate segment fused. First podomere with three setae (d1, d2, dp). Third podomere with one short, curled, reflexed apical (g), one mid-ventral setae (f). Fourth podomere with two short setae (h1, h2) and one long, curved seta (h3) plumed from the tip to half its total length.

Zenker organ ( Figure 15 F) with 5 + 2 internal rings of spines. Proximally with spherical lobe.

Hp ( Figure 15 E) with one distally rounded ventral lobe. Prelabyrinthal inner spermiduct (r) wide, forming thin-walled chamber. Bursa copulatrix (p) simple, with chitinous process (t).

Uropod ( Figure 15 F) with one anterior seta (Sa) and one fine (Sp1), one normal (Sp2) posterior setae. Tips of the two terminal claws (Ga, Gp) with robust spines.

Description of female. Carapace ( Figure 13 A–C) 0.57–0.60 mm long, 0.26–0.28 mm high (n = 3); 0.59 mm long, 0.28 mm high in allotype.

A2 (figure 14D) four-segmented. First (Pr) and second (EI) podomeres similar to those of male. Third podomere (EII + EIII) with claws G1, short G2, G3, setae z1, z2, z3, one mid-ventral aesthetasc y2, one long (t1) and three short mid-ventral setae (t2–4), and one mid-dorsal seta. Fourth podomere (EIV) with GM, shorter Gm, one apical seta, and aesthetasc y3.

Palp of L5 simple, non-segmented, with three apical setae.

Genital lobe with conspicuous, well-developed spiral canal ( Figures 15 G; 16A–D, Supplementary Data 3). Vaginal opening rimmed by sclerotized ring and forming bulbous process ( Figure 16 E, F). Seminal receptacle situated above genital lobe; duct connecting with spiral canal protrudes from mid-posterior part ( Figures 15 G; 16B).

In other characters, female similar to male.

Remarks. Among congeners, Paracypria plumosa sp. nov. is relatively small in body size, though Paracypria minuta McKenzie, 1968 and Pa. adnata Smith & Kamiya, 2006 are similar in body size. Paracypria minuta differs from Pa. plumosa in having a distally pointed lobe on Hp. The new species is generally similar to Pa. adnata from Yakushima Island, Japan, in the size of the carapace, in the shape of Hp, in having a stout claw fused to the terminal podomere of the Md palp, and in lacking a Wouters organ ( Smith & Matzke-Karasz 2008). However, these two species differ in the mid-ventral seta on the penultimate segment in female A2 (long and stout in Pa. plumosa ; fine and short in Pa. adnata ); the stout claw on the terminal segment of the Md palp (forming a brush-like tip in Pa. plumosa ; typical for the genus in Pa. adnata ); the largest terminal tooth on the coxal plate (with a comb-like process in Pa. plumosa ; with denticles along the inner edge in Pa. adnata ); the number of filament-like setae on the male clasping process (three in Pa. plumosa ; two in Pa. adnata ); and Sp1 on the uropodal rami (long in Pa. plumosa ; short in Pa. adnata ).

Figures

FIGURE 13. Paracypria plumosa sp. nov. Females, SEM images; A, B, paratype, ICHUM 4926; C, paratype, ICHUM 4927; D, paratype, ICHUM 4928. (A, B) Lateral views of LV and RV, respectively. (C) Lateral view of female with RV removed. (D) Enlarged image of masticatory apparatuses; arrowheads indicate brush-like fused claw on Md palp, and comb-like structure on terminal tooth of coxal plate.

FIGURE 14. Paracypria plumosa sp. nov. A – C, E, F, holotype, male, ICHUM 4915; D, allotype, ICHUM 4920. (A) Lateral view of LV. (B) A 1. (C) Male A 2 (inset, details of third to fifth podomeres). (D) Female A 2 (inset, details of terminal two podomeres). (E) Md (inset, enlarged details of comb-like process of Md coxa and fused brush-like terminal claw of Md palp). (F) Mx.

FIGURE 15. Paracypria plumosa sp. nov. A – F, holotype, male, ICHUM 4915; G, allotype, ICHUM 4922. (A, B) Left and right male L 5, respectively. (C) L 6 (first podomere not illustrated). (D) L 7. (E) Hp. (F) Uropod and Zenker organ. (G) Uropod and genital lobe with spiral canal.

FIGURE 16. Paracypria plumosa sp. nov. A – F, allotype, female, ICHUM 4922. Serial images of female genital organs. Arrowhead shows vaginal opening rimmed with sclerotized ring. Seminal receptacle is filled with sperms.