Neonesidea alwakasaensis, Asaba & Asaba & Tsukagoshi, 2024

Asaba, Erika, Asaba, Reina & Tsukagoshi, Akira, 2024, Three new interstitial species of the genus Neonesidea (Bairdioidea: Podocopida: Ostracoda) from the infralittoral zone in Japan, Zootaxa 5397 (3), pp. 377-396 : 389

Neonesidea alwakasaensis sp. nov.

( Figs. 7E, F , 10 , 11 )

Type series. All examined specimens collected at infralittoral zone of coarse sand beach in Tai Beach, Wakasa Bay, Kyoto Prefecture, Japan (35°34’52.8”N, 135°14’11.2”E, Loc. 3 in Fig. 1 ) on 9 September 2016. Holotype: adult male ( SUM-CO-2542 ), left valve length 0.84 mm, height 0.47 mm, appendages mounted on glass slide and valves preserved in cardboard cell slide . Paratypes: 5 adult males ( SUM-CO-2536 , 2537 , 2540 , 2541 , and 2543 ) and 3 adult females ( SUM-CO-2538 , 2539 and 2544 ) .

Etymology. After name of type locality, Wakasa Bay. Prefix “al” formed from first letters of Latin words arena (sand) and locus (space), characterising their interstitial habitat.

Description. Carapace ( Fig. 10 ) characters almost corresponding to Neonesidea arenalocus sp. nov. Dorsal margin of valve weakly arched and making waterdrop-like outline. Approximately 12 small but conspicuous spines along postero-ventral margin of right valve. Frills along anterior and posterior margins not developed. No auxiliary dentitions along interior margin.

Eye. Naupliar eye. No eye spot on carapace.

Antennula ( Fig. 11A ). Seven articulated podomeres. Chaetotaxy almost corresponding to Neonesidea arenalocus sp. nov.

Antenna ( Fig. 11 Bm and 11Bf). Five articulated podomeres. Chaetotaxy almost corresponding to Neonesidea arenalocus sp. nov.

Mandible ( Fig. 11C ) consisting of 5 podomeres. Chaetotaxy almost corresponding to Neonesidea arenalocus sp. nov.

Maxillula ( Fig. 11D 1 , D 2 ). Chaetotaxies almost corresponding to Neonesidea alyamanai sp. nov.

Fifth limb ( Fig. 11E 1 , E 2 ) consisting of 5 articulated podomeres. Chaetotaxies almost corresponding to Neonesidea arenalocus sp. nov.

Brush-shaped organ (in male) ( Fig. 11H ), consisting of extremely asymmetrical paired branches. Well-developed branch with more than 10 setae on distal end and 6 conspicuous annulations. Smaller brunch with several setae.

Sixth limb ( Fig. 11F ). Consisting of 5 articulated podomeres. Chaetotaxy almost corresponding to Neonesidea arenalocus sp. nov.

Seventh limb ( Fig. 11G ). Consisting of 5 articulated podomeres. Chaetotaxy almost corresponding to Neonesidea arenalocus sp. nov.

Furca ( Fig. 7E, F ) bearing 7 setae. Terminal-most 2nd seta (2) almost same length as terminal-most (1) seta. Other chaetotaxies almost corresponding to Neonesidea arenalocus sp. nov.

Caudal process ( Fig. 7E, F ). One simple short seta, approximately 20 µm long.

Male copulatory organ ( Fig. 7E ). Basal capsule sub-semicircular and consisting of some lobes. Distal lobe shaped like the head of Raptores. Copulatory duct bending largely at proximal part.

Female genital lobe ( Fig 7F ). Semicircular main lobe with coiled spiral and bent tube inside. Two derivative lobes at proximal end and middle of main lobe.

Dimension. See Table 3 .

Occurrence. Known only from type locality.

Remarks. The general shape of the carapace is similar to that of the other two species, Neonesidea arenalocus sp. nov. and N. alyamanaensis sp. nov. However, this new species does not have a frill in the right valve or auxiliary dentitions along the interior margin. Instead, this new species has approximately 12 small but conspicuous spines along the postero-ventral margin of the right valve. The shape of the distal lobe of the male copulatory organ in this new species is distinguishable from the other two new species. The terminal-most (1) and second-most terminal (2) setae of the furca were almost the same length. The brush-shaped organ in this new species is also distinguishable from that in the other two new species because of the extremely asymmetrical paired branches and the well-developed branch with six conspicuous annulations.

Figures

FIGURE 1. Map showing the sampling localities of Neonesidea species. Miho-Masaki Beach (Loc. 1), Motojima (Loc. 2), and Tai Beach (Loc. 3).

FIGURE 2. Sampling in Miho-Masaki Beach (Loc. 1 in Fig. 1). A, detailed location of Miho-Masaki Beach (Loc. 1). B, sampling scheme in Loc. 1, sediment materials were collected at eight points at 0.5 m intervals. C, individual number / 500 ml of Neonesidea arenalocus sp. nov. (grey bars at the back) and other ostracod species (black bars at the foreground). Materials were collected on 18 June 2015.

FIGURE 7. Copulatory organs, furcae, and caudal process of Neonesidea arenalocus sp. nov. (A, male holotype, SUM-CO2522; B, female paratype, SUM-CO-2525), Neonesidea alyamanai sp. nov. (C, male holotype, SUM-CO-2532; D, female paratype, SUM-CO-2535), and Neonesidea alwakasaensis sp. nov. (E, male holotype, SUM-CO-2542; F, female paratype, SUM-CO-2544). CD, copulatory duct; CP, caudal process; DL, distal lobe. Setae on furcae are numbered (1–7) from distal to proximal. Scale: 100 μm.

FIGURE 10. Carapace morphology of Neonesidea alwakasaensis sp. nov. A and B, male left and right valves, respectively (SUM-CO-2536, paratype). C and D, internal view of male left and right valves, respectively (SUM-CO-2537, paratype). E and F, external view of female left and right valves, respectively (SUM-CO-2538, paratype). G and H, internal view of female left and right valves, respectively (SUM-CO-2539, paratype). I, dorsal view of male carapace (SUM-CO-2540, paratype). J, centre of internal ventral margin of male left valve (SUM-CO-2537, paratype). K, central muscle scars on female left valve (SUM-CO2539, paratype). Scale: 200 μm for A–I, 50 μm for J, K.

FIGURE 11. Appendages of Neonesidea alwakasaensis sp. nov. A, antennule; Bf, antenna of female; Bm, antenna of male; C, mandibula; D1/D2, maxillula; E1/E2, 5th limb; F, 6th limb; G, 7th limb; H, brush-shaped organ. A and D2, male paratype, SUM-CO-2541; Bf, female paratype, SUM-CO-2544; Bm, C, E1, E2, F and G, male holotype, SUM-CO-2542; D1 and H, male paratype, SUM-CO-2543. Scale:100 μm.