Paracypria longiseta Hiruta & Kakui, 2016, sp. nov.

Paracypria longiseta sp. nov.

(Figures 8–12)

Material examined. Holotype: ICHUM 4908 (male), 26°33′36″N, 128°2′37″E, Oura River, Okinawa Island, Japan, 26 February 2011, soft parts mounted on 18 slides, carapace mounted on a microfossil slide. Allotype: ICHUM 4909 (female), collection data same as for holotype, soft parts and carapace mounted on two glass slides. Paratypes: ICHUM 4910 (female), collection data same as for holotype, soft parts mounted on a glass slide, carapace mounted on a microfossil slide; ICHUM 4911 (male) and 4912 (female), same locality as holotype, 22 November 2013, soft parts and carapace mounted on glass slides, carapace mounted on a microfossil slide; ICHUM 4914 (female), collection data same as for ICHUM 4911, mounted on stubs for SEM observation; ICHUM 4913, collection data same as for holotype, exoskeleton and carapace after DNA extraction mounted on a glass slide.

Etymology. The specific name is a noun in apposition, derived from the combination of the Latin longi (long) and seta, referring to the long, filament-like rays on the male L5 palp.

Diagnosis. Carapace with maximum height anterior of mid-length, ventral margin straight, anterior margin broadly rounded, posterior margin sharply rounded. A1 with Rome organ and Wouters organ. Final segment of Md palp with two long claws. Male L5 clasping process symmetrical, with three long mid-ventral rays and one shorter apical filament-like peg protruding from palp. Female L5 with slender palp and very short h1–3 setae. Zenker organ with 5 internal rosettes. Hp small, with protruding, rounded distal lobe. Uropodal ramus with short Sa, fine and very short Sp1–2 setae, and claws Ga and Gp with denticles distally.

COI barcoding sequence. AB920554 (658 bp) from ICHUM 4913 (paratype).

Description of male. Carapace (Figures 8 A; 9A, B) 0.68–0.70 mm long, 0.29–0.30 mm high (n = 3); 0.69 mm long, 0.30 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 9 C) seven-segmented. First two podomeres fused, with two dorsal setae and two long apico-ventral plumose setae, and Wouters organ. Third podomere wider than long, with apico-dorsal seta and Rome organ. Fourth podomere rectangular, with long apico-dorsal seta. Fifth and sixth podomeres both rectangular, each with two long apico-dorsal setae. Seventh podomere with four long apical setae. Eighth podomere elongate, slender, with two long setae, one shorter seta, and aesthetasc ya.

A2 (Figure 9 D) five-segmented. First podomere (Pr) with one long apico-ventral and one antero-proximal setae. Second podomere (EI) with one normal and one finer apico-ventral setae, aesthetasc Y, and Exo which consists of one long and two short setae; 4 + 1 natatory setae extending to tip of A2 terminal claw. Third podomere (EII) with two mid-apical male bristles (t2 and t3), one long apico-ventral (t1) and one apico-dorsal (t4) setae.

Fourth podomere (EIII) with claws G1, short G2, z1, z2, setae G3, short z3, and one short apico-ventral seta. Fifth podomere (EIV) with claws GM and short Gm, and aesthetasc y3.

Md (Figure 10 A) consisting of coxal plate and four-segmented palp. Coxal plate with antero-lateral seta and six stout teeth, latter interspersed with several setae of various lengths. Palp with smooth short alpha seta, and plumed very short beta seta, and plumed long gamma setae. First podomere with exopodal plate (Exo). Terminal podomere of palp with two long claws and three setae.

Mx (Figure 10 B) with elongate vibratory plate, three masticatory processes, and two-segmented palp. First podomere with two plumose setae.

L5 (Figure 10 C, D) with palp, vibratory plate (Exo), one antero-proximal seta, one antero-apical seta, and one postero-apical seta. Vibratory plate with four filaments. Palp transformed into two-segmented symmetrical clasping process; first segment with three long mid-ventral filament-like rays, one shorter apical filament-like peg. Terminal segment (Figure 10 C, D) stout, curved, with one terminal seta. Masticatory process with numerous setae.

L6 (Figure 10 E) five-segmented. Fifth podomere with one long terminal claw (h2) one short, and one indistinct short, fine setae (h1, h3).

L7 (Figure 10 F) four-segmented. Penultimate segment fused. First podomere with three setae (d1, d2, dp). Third podomere with one apical (g), one mid-ventral setae (f). Fourth podomere with two short (h1, h2) setae and one long, terminally curved seta (h3) plumed from the tip to three-fourths of its total length.

Zenker organ (Figure 11) with 5 + 2 internal rings of spines. Entrance to organ formed as a small star-shaped hole in a spherically shaped proximal end.

Hp (Figure 10 H) with large, round terminal outer lobe. Prelabyrinthal inner spermiduct (r) forms relatively large, thin-walled chamber. Bursa copulatrix (p) distally stout and rounded.

Uropod with one anterior seta (Sa) and two reduced posterior setae (Sp1, Sp2). Tips of the two terminal claws (Ga, Gp) with tiny denticles.

Description of female. Carapace 0.71–0.76 mm long, 0.31–0.33 mm high (n = 3); 0.75 mm long, 0.33 mm high in allotype.

A2 (Figure 9 E) four-segmented. First (Pr) and second (EI) podomeres similar to those of male. Third podomere (EII + EIII) with claws G1 G2, G3, and short z1, setae z2, z3, one mid-dorsal seta, and one long, three short mid-ventral setae. 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 protrude posteriorly, with conspicuous, well-developed spiral canal (Figures 10 G; 12A–C, Supplementary Data 2). Vaginal opening rimmed with sclerotized ring (Figures 10 G; 12D–F). From the lateral view, this opening situated at inner, proximal part of the genital lobes.

In other characters, female similar to male.

Remarks. Although we place this species in the genus Paracypria, it is generally similar to Pontoparta hartmanni Keyser, 1975. Wouters (1998) noted that there were some ill-defined genera in the tribe Thalassocypridini, including the genus Pontoparta. In a statistical analysis of affinities among 40 species representing seven genera in this tribe, based on 49 morphological characters, Maddocks (2005) found that the genus Pontoparta was inadequately diagnosed and needed redescription. The type species, Po. rara Várvra, 1901 had been described from one female specimen, and the holotype might be lost (Wouters 1 998). A temporary solution to this problem has been to avoid using the genus Pontoparta and to transfer species other than Po. rara to Paracypria (K. Wouters pers. comm.).

Paracypria longiseta sp. nov. is of medium carapace size (around 0.7 mm long) among the species in Paracypria and Pontoparta. Paracypria tenuis Sars, 1905, Pa. inopinata (Klie, 1939), Pa. uberis Maddocks, 2005, and Po. hartmanni Keyser, 1975 are similar in body size. The former three species differ from Pa. longiseta in having a distally broad lobe on each Hp. Especially in Pa. tenuis and Pa. uberis, additional processes are situated at the outer edge of the distal lobe. The shapes of the carapace and appendages are similar between Pa. longiseta and Po. hartmanni. However, Po. hartmanni, reported from Florida Everglades, USA, and redescribed by Maddocks & Iliffe (1993), clearly differs in the shape of the outer lobe shape of Hp (triangular in Po. hartmanni; protruding farther and more rounded in Pa. longiseta), the male clasping process on L5 (with two relatively short rays in Pa. hartmanni; with three long, mid-ventral filament-like rays and one shorter apical filament-like peg in Pa. longiseta), and the posterior setae on the uropodal rami (typical for the genus in Po. hartmanni; reduced and difficult to find in Pa. longiseta).