Eudiaptomus transylvanicus ( Daday, 1891 )

Podshivalina, V. N., Sheveleva, N. G., Semenova, A. S. & Mirabdullayev, I. M., 2022, Eudiaptomus transylvanicus and E. vulgaris (Copepoda: Calanoida: Diaptomidae): comparative morphology, distribution and ecology, Zoosystematica Rossica 31 (1), pp. 42-54 : 44

Eudiaptomus transylvanicus ( Daday, 1891)

( Figs 1 , 2 )

Material examined. Russia, Chuvash Republic , near Atrat Vill., “kopan’” water body, 54.9991°N 46.6685°E, 3 July 2019, 9 males, 8 females ; same locality, quarry pond, 54.97798°N 46.72082°E, 26 May 2020, 2 males, 2 females ; same locality, carr lakelet, 54.97798°N 46.72082°E, 26 May 2020, 4 males (all E. Osmelkin leg.).

Redescription. Female ( Fig. 1a ). Body length 1.60–1.66 mm (n = 8). Last thoracic segment with well-developed asymmetrical wings. Genital compound somite gently dilated in central part, with medium-sized hyaline spines ( Fig. 1b , arrowed). Antennules extending closely to apices of apical caudal setae ( Fig. 1a ). Rostrum with two strong long curved asymmetrical processes ( Fig. 1d ). Edge of mandibular incision with single-vertex teeth: one ventral and six or seven central ( Fig. 1c, 1c′ ). Ventral tooth separated from other teeth by a deep diastema ( Fig. 1c′ ). Rather deep diastema present between outer ventral central tooth and other teeth. Central teeth acute, with wide base ( Fig. 1c′ ). Dorsal teeth double-vertex, acute, with narrow base. Maxilla and maxilliped with long plumose setae increasing filtration; these setae situated on sympodite compounds (precoxopodite, coxopodite), basipodite and endopodite. In leg 2, endopod segment 2 with Schmeilsche lobus ( Fig. 1e , arrowed). In leg 5, coxa with triangular lateral projection, with wide base, nearly as large as basipod ( Fig. 1f ); exopod segment 1 rectangular; exopod segment 2 with spine (bearing row of spinules) at base of segment 3 ( Fig. 1g′ ) and with terminal claw bearing row of spinules on lateral and medial margins ( Fig. 1g ); exopod segment 3 with two apical spines ( Fig. 1g ), longest spine extending to apex of terminal claw; endopod two-segmented, as long as exopod segment 1 or even longer, with distal row of setulae and with relatively long unequal setae: one apical and one subapical ( Fig. 1h ).

Male ( Fig. 2a ). Body length 1.40–1.55 mm (n = 9). Rostrum with two strong long curved processes and one distinct lateral process ( Fig. 2c ). Left antennule extending to middle of urosome. Right antennule with spiniform projections on segments 10, 11 and 13–16; segment 13 with longest projection ( Fig. 2b ); antepenultimate segment with small hyaline process ( Fig. 2b′ , arrowed). In right leg 5 ( Fig. 2d ), coxa with elongate projection supplied with hyaline spine; basis with two well-visible hyaline processes in proximal and distal parts of medial margin and with a small hook-shaped process between them ( Fig. 2e , arrowed), with granulate (not spinulate) surface near distal process ( Fig. 2e ); exopod segment 1 wider than long, with distinct acute dilation at outer distal corner; exopod segment 2 about 1.7 times as long as wide, with strong slightly curved claw and granulate (not spinulate) surface near it ( Fig. 2f , arrowed), with lateral dentate spine inserted in distal part of lateral margin ( Fig. 2f ); endopod two-segmented, reaching one-third of proximal part of exopod segment 2, with distal brush of setulae and three apical setulae ( Fig. 2g ). In left leg 5 ( Fig. 2d ), basis slightly narrowing distally, with small lateral process near distal margin; exopod two-segmented, with thick setae in middle of segment 1 and in proximal part of segment 2; proximal part of exopod segment 1 wider than its distal part; exopod segment 2 with long dentate spine (exopod 3, according to Dussart & Defaye, 2001) being slightly curved in proximal part, with tiny hairs on anterior surface and with five overlapping membranous folds on distomedial surface ( Fig. 2h ); endopod two-segmented, weak.

Figures

Fig. 1. Eudiaptomus transylvanicus (Daday, 1891), female. a – habitus, lateral view; b – genital compound somite; c, c′ – mandible; d – rostrum; e – endopod of leg 2, with Schmeilsche lobus; f – leg 5; g – exopods 2 and 3 of leg 5; h – endopod of leg 5. Scale bars: 0.5 mm (a), 200 µm (b), 50 µm (c, e), 40 µm (d, g), 10 µm (c′, f, h).

Fig. 2. Eudiaptomus transylvanicus (Daday, 1891), male. a – habitus, ventral view; b, b′ – right antennule; c – rostrum; d – leg 5; e – basis of right leg 5; f – exopod 2 of right leg 5; g – endopod of right leg 5; h – exopod 2 of left leg 5. Scale bars: 500 µm (a), 200 µm (b), 100 µm (b′, c, d), 40 µm (e), 30 µm (f), 20 µm (g, h).