Cavernocypris cavernosa, Smith, Robin J., 2011

Smith, Robin J., 2011, Groundwater, spring and interstitial Ostracoda (Crustacea) from Shiga Prefecture, Japan, including descriptions of three new species and one new genus, Zootaxa 3140, pp. 15-37 : 16-20

publication ID	https://doi.org/ 10.5281/zenodo.207945
DOI	https://doi.org/10.5281/zenodo.6185459
persistent identifier	https://treatment.plazi.org/id/03EE4061-BE46-701A-ACAD-E195FE8CFD40
treatment provided by	Plazi
scientific name	Cavernocypris cavernosa
status	sp. nov.

Treatment

Cavernocypris cavernosa n. sp.

( Figs 1A–H View FIGURE 1. A – H , 2 View FIGURE 2 )

Material examined. Two females from gravel in the riverbed of the Myo-odani River, Katsuragawabomura-cho, Otsu, Shiga Prefecture, N35º 14’ 38.3”, E135º 52’ 19.9”, 4 October 2007. Two females from the head of a spring by the edge of a track in Hino-cho, Shiga Prefecture, N35º 00’ 06.2”, E 136º 19’ 47.6”, 16 April 2008. Eight females from a hole dug into the riverbank of a tributary of the Yasu River, Tsuchiyama-cho, Koka, Shiga Prefecture, N35º 00’ 18.1”, E136º 22’ 26.7”, altitude 608 m, 29 January 2010. Four females, six empty carapaces and five isolated valves from muddy gravel at the edge of a large spring in a steep sided river valley, Gongendani, Taga-cho, Shiga Prefecture, N35º 15’ 29.5”, E136º 21’ 49.4”, 30 September 2009. All material collected by the author.

Etymology. From the Latin cavernosus, meaning full of hollows or cavities, referring to the pitted ornamentation of the carapace.

Type locality. Large spring flowing from a limestone outcrop in Gongendani, Taga-cho, Shiga Prefecture, Japan, N35º 15’ 29.5”, E136º 21’ 49.4”. Substrate gravel, sand and a little mud.

Type material. Type material is from the type locality unless otherwise stated. Holotype: dissected female ( LBM 1430005063). Paratypes: two dissected females ( LBM 1430005064, LBM 1430005065), one empty carapace ( LBM 1430005066 from Myo-odani River, Katsuragawabomura-cho), two left valves ( LBM 1430005067, LBM 1430005068) and two right valves ( LBM 1430005069, LBM 1430005070).

Diagnosis. Carapace in lateral view elongate, maximum height towards the anterior, dorsal margin straight, posterior of maximum height, anterior margin more inflated than posterior margin. Dorsal view compressed, anterior and posterior margins equally rounded. Both valves lacking external lists. Left valve overlaps right valve. Carapace covered in well-defined, small pits. Wouters and Rome organs of antennule both relatively large and elongate. Antenna with strongly reduced natatory setae, claw G2 with strongly defined spines along posterior edge. Branchial plate of fifth limb with two rays. Sixth limb with relatively long e and f setae. Caudal ramus flagellumlike.

Description. Carapace ( Figs 1A–H View FIGURE 1. A – H , 2 View FIGURE 2 A) length 555–609 µm, height 269–314 µm. Lateral view with maximum height anterior of mid-length, with middle part of hinge straight, marked by distinct angles each end, sloping down towards posterior. Anterior margin more inflated than posterior margin, maximum curvature of both margins below mid-height. Ventral margin slightly concave. Left valve overlaps right along all margins. Both valves lack external lists near ventral margins ( Figs 1G, H View FIGURE 1. A – H ). Both valves with weak inner lists in ventro-posterior regions ( Fig. 1C, D View FIGURE 1. A – H ). Inner calcified lamella wide both posteriorly and anteriorly. Fused zone broad along ventral margin, distinctly enlarged in antero-ventral section, with numerous marginal pore canals. In dorsal view, both anterior and posterior margins equally rounded, maximum width approximately at mid-length. Surface of valves covered in numerous shallow pits, most distinct towards anterior and posterior margins, less distinct in central area. Colour pale greyish/ white with slight green tint in posterior and anterior regions.

Eye present but small.

An1 ( Fig. 2 View FIGURE 2 B) with eight segments, the first two of which partially fused together. First segment with relatively large and elongate Wouters organ on dorsal edge. Second segment with one seta on dorsal edge and two setae towards apical-ventral corner. Third segment with elongate Rome organ and one apical-dorsal seta. Fourth segment with one short apical-dorsal seta and one tiny apical-ventral seta. Fifth and sixth segments each with two long apical-dorsal setae and two much smaller apical-ventral setae. Seventh segment with four long and one very short (alpha seta) apical setae. Final segment with one long and two mid-length setae, and long aesthetasc y a.

An2 ( Figs 2 View FIGURE 2 C, D) with strongly reduced natatory setae on inner edge of first endopodal segment. Claw G1 slightly longer than both G2 and G3. Claw G2 with robust spines along posterior distal edge. GM slender, reaching to end of G2, Gm much smaller, about half-length of GM.

Md ( Figs 2 View FIGURE 2 E, F). Alpha seta small and slender. Beta seta with wide base, tapering to hirsute distal end. Gamma seta relatively slender with setules on distal half.

L5 ( Fig. 2 View FIGURE 2 G) with two small a setae on basis, and branchial plate consisting of two rays. Endite with approximately ten apical setae. Endopodite terminating with three setae of unequal length, longest of which very long.

L6 ( Fig. 2 View FIGURE 2 H) with five segments, first four very elongate. First segment with d2 seta, but d1 seta absent. Second and third segments with relatively long e and f setae. Fourth segment with small g seta. Final segment small and quadrate supporting tiny h3 seta, short h1 seta and very long, stout h2 claw.

L7 ( Fig. 2 View FIGURE 2 I) with sub-equal length d1, d2 and dp setae on first segment. Second segment with short e seta. Third segment with f seta protruding from mid-length. Distally with well-developed pincer arrangement.

CR ( Fig. 2 View FIGURE 2 J) strongly reduced and flagelliform, typical of subfamily, consisting of small, elongate base supporting one long and one short setae.

Remarks. Four species/subspecies of Cavernocypris have previously been described. The carapace shape and morphology of the appendages, including the two branchial rays on the fifth limb of Cavernocypris cavernosa n. sp. are similar to those of Cavernocypris subterranea ( Wolf, 1920) . However, C. subterranea only has shallow pits in the central part of the carapace, whereas the entire carapace of C. cavernosa n. sp. is covered with shallow pits, and the pits in the posterior and anterior regions are more developed than those of the central area. Additionally, C. subterranea has well-developed lists on the outer ventral margin of both valves, in contrast to C. cavernosa n. sp., which lacks similar lists ( Figs 1G, H View FIGURE 1. A – H ). Cavernocypris wardi Marmonier, Meisch and Danielopol, 1989 is not pitted, has a tighter curved posterior margin compared with C. cavernosa n. sp., and has three branchial rays on the fifth limb. Both Cavernocypris coreana coreana ( McKenzie, 1972) and Cavernocypris coreana elongata ( McKenzie, 1972) are somewhat different in carapace shape (the former being sub-triangular, the latter more elongate) compared to C. cavernosa n. sp. and additionally have four branchial rays on the fifth limbs and only six antennule segments.

Cavernocypris cavernosa n. sp. has a well-developed and relatively large Wouters organ on the first segment of the antennule, the first time such an organ has been found in this genus. It is unclear if other Cavernocypris View in CoL have a similar Wouters organ as the presence of the Wouters organ in the family Cyprididae View in CoL has only recently been recognized ( Karanovic 2005; Smith & Matzke-Karasz 2008).

Cavernocypris cavernosa n. sp. was found in low numbers in holes dug into coarse, poorly sorted gravels of rivers and springs.