Cavernocypris hokkaiensis, Munakata & Tanaka & Kakui, 2022

Munakata, Mizuho, Tanaka, Hayato & Kakui, Keiichi, 2022, Taxonomy and natural history of Cavernocypris hokkaiensis sp. nov., the first ostracod reported from alpine streams in Japan, Zoosystematics and Evolution 98 (1), pp. 117-127 : 117

publication ID

https://dx.doi.org/10.3897/zse.98.80442

publication LSID

lsid:zoobank.org:pub:47425689-5924-4BD7-909E-8726BD15A873

persistent identifier

https://treatment.plazi.org/id/3DBCDFE2-957F-485F-A91E-036E71EC75C0

taxon LSID

lsid:zoobank.org:act:3DBCDFE2-957F-485F-A91E-036E71EC75C0

treatment provided by

Zoosystematics and Evolution by Pensoft

scientific name

Cavernocypris hokkaiensis
status

sp. nov.

Cavernocypris hokkaiensis sp. nov.

Figs 2 View Figure 2 , 3 View Figure 3

Etymology.

The epithet Cavernocypris hokkaiensis is an adjective referring to the type locality, Hokkai-sawa Stream in Japan.

New Japanese name.

Shibare-doukutsu-kaimijinko, referring to the habitat having low water temperature. Shibare is derived from the Japanese verb shibare-ru (freeze), in a Hokkaido dialect; Doukutsu-kaimijinko is the Japanese name for Cavernocypris ( Tanaka et al. 2015).

Type locality.

Hokkai-sawa Stream, Daisetsuzan National Park, Hokkaido, Japan (Stn. 1: 43°41'08"N, 142°55'28"E).

Holotype: female, ICHUM-8247, one slide and one SEM stub, Stn.1, Hokkai-sawa Stream, riverbed sediment, 26 July 2021. Paratypes (five females): ICHUM-8248, 8249, one SEM stub and one slide for each; ICHUM-8250, 8251, one SEM stub; ICHUM-8252, one slide, voucher specimen for LC666823 (COI) and LC666824 (18S). Collection data for ICHUM-8249, 8252 are same as holotype; ICHUM-8248, 8251 were collected from Stn. 2 (43°41'17"N, 142°54'33"E) on 25 August 2020; ICHUM-8250 was collected from Stn. 1 on 25 August 2020. All individuals were collected by Mizuho Munakata.

Description of females.

Measurements (in millimeters, except for ratios) of carapace and valves: LV-L, 0.59-0.61 (0.60, N=3); LV-H, 0.30-0.31 (0.31, N= 3); LV-H/LV-L, 0.50-0.51 (0.51, N=3); RV-L, 0.58-0.61 (0.60, N=3); RV-H, 0.29-0.31 (0.30, N=3); RV-H/RV-L, 0.50-0.51 (0.51, N=3); Ca-W, 0.25-0.26 (0.26, N=2); Ca-W/LV-L, 0.41-0.42 (0.42, N=2).

Carapace (Fig. 2 View Figure 2 ) translucent white, with black eye; outer surface smooth, with sparse, tiny setae but without shallow pits; widest point at about mid-length (Fig. 2A, B View Figure 2 ); LV overlapping RV at ventral margin (Fig. 2A View Figure 2 ); no dorsal hump on LV (Fig. 2B-D View Figure 2 ); outer list present in ventral margin of both valves (Fig. 2A View Figure 2 ).

LV (Figs 2C, E, G View Figure 2 , 3A View Figure 3 ) with greatest height at about mid-length; anterior and posterior margins evenly rounded; apex of anterior margin lower than mid-height of LV and slightly higher than apex of posterior margin; in inner view, calcified inner lamella on anterior and posterior margins well developed (Figs 2E View Figure 2 , 3A View Figure 3 ); inner list present in ventral region (Fig. 2G View Figure 2 ); mid-ventral margin with inner triangular projection (Fig. 2A, G View Figure 2 ). RV (Figs 2D, F, H View Figure 2 , 3B View Figure 3 ) similar to LV in shape; inner list in ventral region absent (Fig. 2H View Figure 2 ). Two oblong mandibular muscle scars and four oblong adductor muscle scars on LV and RV (Figs 2E, F View Figure 2 , 3A, B View Figure 3 ). Hinge adont.

An1 (Fig. 3C View Figure 3 ) with seven podomeres. First podomere with one dorsal and two ventrodistal plumed setae and Wouters organ. Second podomere with dorsodistal seta reaching distal edge of third podomere and Rome organ. Third podomere with dorsodistal seta reaching distal edge of fourth podomere and ventrodistal seta extending beyond middle of fourth podomere. Fourth podomere with two dorsodistal setae of unequal length (longer one extending to distal edge of seventh podomere) and two ventrodistal setae reaching distal edge of sixth podomere. Fifth podomere with two dorsodistal setae of unequal length (longer one as long as podomeres 2-7) and two shorter ventrodistal setae. Sixth podomere with four outer distal setae as long as podomeres 1-7 and shorter inner distal seta. Seventh podomere with three distal setae of unequal length and aesthetasc ya (ca. 60% length of longest seta).

An2 (Fig. 3D View Figure 3 ) with five podomeres. First podomere (coxa) with two ventral setae. Second podomere (basis) with ventrosubdistal seta reaching distal edge of third podomere. Exopodite with one long and two unequal short setae. Third (first endopodal) podomere with six inner subdistal short natatory setae extending slightly beyond distal edge of third podomere, ventrodistal plumed seta reaching distal edge of fifth podomere, and mid-ventral aesthetasc Y. Fourth podomere undivided, with two mid-dorsal setae, dorsosubdistal setae z1-3 extending beyond middle of claws G2,3, mid-ventral plumed setae t1-4 of unequal length, and distal claws G1-3 of nearly equal length. Fifth podomere with bifurcate aesthetasc y3 (longer part half the length of claw GM) and claws Gm,M; Gm ca. 70% length of GM; GM reaching tip of claws G1-3.

Md (Fig. 3E, F View Figure 3 ) with coxa, palp comprising four (one basal and three endopodal) podomeres, and vibratory plate. Coxa with several distal teeth and one subdistal plumed seta. First podomere (basis) with one ventrodistal seta, ventrodistal setae S1,2, and ventrodistal short seta α; setae S1,2 subequal in length, bearing row of long setules. Vibratory plate (exopodite) with four rays. Second (first endopodal) podomere with three dorsodistal setae of unequal length (longest reaching tip of claws on fourth podomere), four mid-ventral long plumed setae (not extending beyond tip of claws on fourth podomere), and mid-ventral plumed short seta ß (shorter than half the length of mid-ventral plumed setae). Third podomere with four dorsosubdistal setae and two ventrosubdistal setae; inner distal region with plumed seta γ and two plumed setae. Fourth podomere with two distal setae and four distal claws.

Mx (Fig. 3G View Figure 3 ) with palp comprising two podomeres, three endites, and vibratory plate (not illustrated). First palpal podomere with five dorsodistal setae of unequal length and one ventro-subdistal seta. Second palpal podomere not spatula-like, but rectangular, with two distal setae and three distal claws. First endite with two ventroproximal setae and ca. nine distal setae. Second endite with ca. eight distal setae. Third endite with two distal serrated spines and six distal setae.

L5 (Fig. 3H View Figure 3 ) with protopod and palp; vibratory plate absent. Protopod with two setae a and at least nine distal plumed setae of unequal length; setae b, c, and d absent. Palp with distal plumed setae h1-3.

L6 (Fig. 3I View Figure 3 ) with six podomeres. First and second podomeres (protopod) with seta d2. Third (first endopodal) podomere with ventrodistal plumed seta e reaching middle of fifth podomere. Fourth podomere with ventrodistal plumed seta f reaching beyond distal edge of fifth podomere. Fifth podomere with ventrodistal plumed seta g. Sixth podomere with dorsodistal seta h3, ventrodistal plumed seta h1, and distal curved claw h2.

L7 (Fig. 3J View Figure 3 ) with four podomeres; third and fourth podomeres fused to form pincer organ. First podomere (protopod) with plumed setae d1,2,p. Second (first endopodal) podomere with ventrodistal plumed seta e not reaching middle of fused podomeres 3 and 4. Fused third and fourth podomeres with mid-ventral plumed seta f not reaching tip of L7, subdistal long plumed seta h3, distal hook-like seta h2, and subdistal tiny seta h1.

UR (Fig. 3K View Figure 3 ) strongly reduced. Proximal part longer than wide, with one seta. Distal part flagellar in shape.

Rake organ (Fig. 3L View Figure 3 ) with stout rod and ca. eight blunt distal teeth.

Genital hooks on female copulatory organ present (not illustrated).