Mecynocera clausi I.C. Thompson 1888

Mecynocera clausi I.C. Thompson, 1888

Mecynocera clausi I.C. Thompson, 1888: 150, pl. 11, figs 1–4. Giesbrecht, 1893: 160, 161, pl. 5, fig. 1, pl. 11, figs 43– 45, pl. 35, figs 21, 22.- Andronov, 1970: 980 –984, figs 1, 2.- Corral, 1972: 37, pl. 11.- Bradford-Grieve 1994: 71, fig. 38.

Dolichocera tenuis.- Bernard, 1958: 195, fig. 15a (not Calocalanus tenuis Farran, 1926). Dolichocerea tenuis.- Bernard, 1963: 160 (not Calocalanus tenuis Farran, 1926).

Material examined: 4 males, eastern tropical Atlantic collected by the Alfred Wegener Institute of Polar and Marine Research, Bremerhaven, Germany, ANT XX/1, Station 18, 20 o 26’S, 0 5o 55’E, 19 November 2002, 0– 300 m. One specimen in formalin (NIWA 45661), two specimens dissected and mounted on slides, one specimen mounted whole on slide (NIWA 45661/1-3).

Supplementary description of male: Male 0.91 mm total length (Fig. 1 A)

Antennules symmetrically developed, neither of them geniculate, with 21 free segments, ancestral segments I–IV, V–VIII, XXVII–XXVIII fused.

Antenna (Fig. 2 A) well developed, sexually dimorphic. Basis with 2 setae. Endopod 2-segmented, segment 1 without setae, segment 2 with 6 + 6 setae. Exopod 6-segmented, segment 1 short without seta, segment 2 elongate bearing enlarged distal seta, segments 3–6 each with 1 seta.

Mandible (Fig. 2 B) with degenerate gnathobase. Palp well developed. Endopod 2-segmented, segment 1 with 2 setae, segment 2 with 8 setae, 5 of which elongate, exopod with 6 setae.

Maxillule (Fig. 2 C) reduced with degenerate inner lobes and endopod with 2 small setae. Exopod with 8 setae, praecoxal epipodite with 6 large setae.

Maxilla (Fig. 2 D) reduced to a small, knob-like remnant.

Maxilliped (Fig. 2 E) sexually dimorphic. Inner setae of syncoxa, basis and endopod segments absent or very reduced; 1 terminal and 2 outer endopod setae enlarged, plumose, 2 outer setae directed towards base of limb as is typical of Paracalanidae, Calanidae and Eucalanidae.

Leg 1 (Fig. 1 B) endopod indistinctly 2-segmented, segment 1 without inner seta, segment 2 with 2 terminal and 1 inner setae. Exopod segments 1 and 2 without outer distal spines and 1 seta on inner border of both segments, segment 3 with 1 outer border spine, 1 terminal spine and 4 inner border setae. Surfaces of rami not ornamented.

Leg 2 (Fig. 1 C) endopod 3-segmented, segments 1 and 2 each with 1 inner seta, segment 3 with 2 inner, 2 terminal and 1 outer setae. Exopod 3-segmented, segment 1 with 1 outer distal spine and without inner border seta, segment 2 with 1 outer distal spine and 1 inner distal seta, segment 3 with 2 outer border spines, 1 distal spine and 5 inner setae. Surfaces of rami not ornamented.

Leg 5 (Fig. 1 D) with right leg longest, 5-segmented on both sides, terminal segment on each side with 1 stout terminal spine and 1 small distal outer border setule. Surfaces of legs not ornamented.