Diaphanosoma macrophthalma Korovchinsky et Mirabdullaev, 1995

Korovchinsky, Nikolai M. & Sanoamuang, La-Orsri, 2008, Overview of Sididae (Crustacea: Cladocera: Ctenopoda) of Northeast and East Thailand, with description of a new species of the genus Diaphanosoma, Zootaxa 1682, pp. 45-61 : 53-55

Diaphanosoma macrophthalma Korovchinsky et Mirabdullaev, 1995

( Figs 26–29 )

Korovchinsky et Mirabdullaev, 1995: 238–240, figs 1–22; Korovchinsky, 2004: 297–301, Figs 107–109.

Material: 1) NE 430: Nong Tae swamp, Muang dt., Ubon Ratchathani Province, 0 2.06.2001, 1 adult female; 2) NE 443: Hui Lam Sebai marsh, Loeng Nok Thad dt., Yasothon Province, 0 2.06.2001, some adult females; 3) NE 574: small pond in floodplain of Mun River, Rattanaburi dt., Surin Province, 1 adult female; 4) LT 007: Hui Kud Noi Reservoir near Ban Tha Kok Daeng, Kham Ta Kla dt., Nong Khai Province, 0 4.2003, 1 adult female; 5) LBKL: Lake Bueng Khong Long in Nam Tok Tat Kham Forest park, Bueng Khong Long dt., Nong Khai Province, 0 8.2002, some adult females; 6) SK 39: Yam River, Akat Amnuai dt., Sakon Nakhon Province, 31.08.2004, 2 deformed adult females; 7) SK 40: canal at Hui Nong Nam Jun, Akat Amnuai dt., Sakon Nakhon Province, 31.08.2004, 1 adult female.

Diagnosis. Head large, rectangular, with well developed dorsal part ( Fig. 26 ). Eye large. Swimming antennae massive and long, reaching or extending past posterior valve margin. Distal outer side of antennal basipodite with relatively large lanceolate spine ( Fig. 27 ). Proximal segment of upper two-segmented antennal branch with prominent distal spine ( Fig. 28 ). Formula of antennal setae 4–8 / 0–1–4. Ventral valve margin with relatively narrow inflexion smoothly connected with ventro-posterior margin and bearing 10–12 long feathered setae. Ventro-posterior valve margins bear 25–30 denticles, in groups of 2–4 ( Fig. 29 ). Thin setules between the groups and 3–5 of them present above the row of denticles. One inner small spine near posterior margin of each valve.

Remarks. The general appearance and most diagnostic features of the Thai specimens correspond well to the original description of the nominate species except for one feature–large number of denticles along postero-ventral valve margins. To evaluate the taxonomic significance of the latter feature, it is necessary to revise its variability in specimens from all the species' range.

Distribution. Until recently, this species was known to be distributed from Middle Asia to Korea and Japan approximately within latitudes 30° and 45° N ( Korovchinsky 2004). Now it is found far to the south — in tropical South-East Asia, namely in Northeast Thailand at 15–18° S. Here it was found in low numbers in seven localities in provinces Nong Khai, Sakon Nakhon, Ubon Ratchathani, Yasothon, and Surin.

Figures

FIGURES 23 – 29. Diaphanosoma elongatum sp. nov., gamogenetic female, Yam River, Akat Amnuai dt., Sakon Nakhon Province, Thailand, 31.08. 2004. 23) general lateral view, 24) resting egg, 25) the same, enlarged. Diaphanosoma macrophthalma, female, marsh in Hui Lam Sebai, Loeng Nok Tha dt., Yasothon Province. 26) general lateral view, 27) distal part of antennal basipodite, outer side, 28) distal part of proximal segment of upper antennal branch, 29) posteroventral valve margin. Scale bars in mm.