ISHIDAI, Kotov & Garibian & Bekker & Taylor & Karabanov, 2021

Kotov, Alexey A., Garibian, Petr G., Bekker, Eugeniya I., Taylor, Derek J. & Karabanov, Dmitry P., 2021, A new species group from the Daphnia curvirostris species complex (Cladocera: Anomopoda) from the eastern Palaearctic: taxonomy, phylogeny and phylogeography, Zoological Journal of the Linnean Society 191 : -

DAPHNIA ( DAPHNIA ) ISHIDAI SP. NOV.

( FIGS 5–8)

LSID: urn:lsid:zoobank.org:act:D8304465-FB1D-4365-9B2F-7C10D2130F0A

Daphnia sp. from Ootori-Ike of Kotov et al., 2006: 1070–1071, table 1, fig. 2.

Daphnia sp. ( Japan) of Juracka et al., 2010: fig. 9.

Daphnia sp. nov., clade J of Kotov & Taylor, 2019: figs 1, 2.

Etymology: This species is dedicated to Dr Seiji Ishida, who contributed to the study of D. curvirostris - like species and other cladocerans in Japan (see Ishida et al., 2006; Kotov et al., 2006) and collected the type series of this species.

Type locality: Lake Otori Ike (38.3658°N, 139.8302°E, 963 m a.s.l.), Yamagata Prefecture, North part of Honshu Island, Japan. The type series was collected on 10 October 2005 by S. Ishida .

Holotype: A parthenogenetic female, MGU Ml177. Label of the holotype: ‘ Daphnia ishidai sp. nov., 1 parth. ♀, Lake Otori ike, Honshu Osland, Japan, HOLOTYPE’.

Paratypes: Fifteen parthenogenetic females, MGU Ml178. Five juvenile males, MGU Ml179. Ten parthenogenetic females, MGU Ml180 .

Short diagnosis: Parthenogenetic female. Body subovoid; caudal spine short. Head relatively small, lacking an anterior crest, its posterior margin with a regularly arched projection; no deep incision between antenna I and labrum base. Rostrum relatively short (as a result, tips of longest aesthetascs reach its tip); rostrum tip slightly bent anteriorly and subdividing into two lobes by a ‘line’ of prerostral fold, with posterior lobe always larger than anterior one. Spinules present only on caudal spine and dorsal margin immediately near caudal spine. In posterior portion of valve, on inner face of valve, only a row of minute setules, but any setae absent. First abdominal process almost straight, directed anteriorly; second process short, bent distally; third process as a massive mound on the segment. Postabdomen with a smooth postanal angle. Postabdominal claw with three pectens of relatively rough denticles, among which denticles in third (distal) row are only somewhat shorter than the rest. Body of antenna I completely reduced; antennular sensory seta not found; aesthetascs protruding posteroventrally, and their tips reach tip of rostrum. Limbs I with relatively long setae 2 and 3; limb II with a relatively short anterior seta 1, bearing fine setules and 10–11 setae of filter plate of gnathobase; limb III with seta 2 of exopod III bearing medium-sized setules; seta 2 on exopodite III longer than seta 4; seta 3 on inner distal portion of moderate size; limb V with projected inner distal portion.

Juvenile female and male of first instar without a neck tooth.

Ephippial female with straight dorsal margin of valves; ephippium with two resting eggs, axes of which are perpendicular to its dorsal margin; egg chambers not separated from each other; posterodorsal portion of valves with caudal spine incorporated into ephippium.

Adult male with dorsal margin of valves almost straight, not elevated above head; depression between head and valves shallow; head with a well-developed rostrum, without a supra-occular depression. No setae and even setules on inner face of posterior margin. Abdomen with first and second processes as rounded mounds. Postabdomen with maximum height in its middle; postanal angle projected. Gonopore opens subdistally, without a genital papilla. Postabdominal claw as in female. Antenna I with notably small antennular seta, located far from distal end of antenna I body; male seta (flagellum) long, bisegmented; its distal segment naked, with a hooked tip. Limb I with ODL bearing a rudimentary seta and a large seta supplied with minute setules distally; on endite 3 both setae 2 and 2′ are relatively long. Limb II distal-most endite with a short, hook-like anterior seta 1, with setulated distal segment, along one side its basal-most setules are markedly robust.