Sphegina (Asiosphegina) crucivena, Hippa, Heikki, Steenis, Jeroen Van & Mutin, Valeri A., 2015

Hippa, Heikki, Steenis, Jeroen Van & Mutin, Valeri A., 2015, The genus Sphegina Meigen (Diptera, Syrphidae) in a biodiversity hotspot: the thirty-six sympatric species in Kambaiti, Myanmar, Zootaxa 3954 (1), pp. 1-67 : 34-35

Sphegina (Asiosphegina) crucivena sp. n.

Figs 2 D, 19A–D

MALE. Body length not measureable, wing length 7.3 mm. Head. Lost in both males studied. Thorax. Colour dull dark brownish to black, postpronotum and postalar callus dark yellow; pleura dark orange-brown; scutum black, pollinose, with non-pollinose, semi-shiny vitta medially; the pile of scutum short, adpressed and light; scutellum semicircular, shiny, brownish, ratio of length:width 1:2.5, pile similar to the posterior part of scutum, a pair of thin, not longer than scutellum, widely separated, pale setae at apical margin. Wing, Fig. 2 D. Hyalinous, stigma yellow, infuscated along transversal veins. Legs. Pro- and mesoleg yellow, tarsomeres 4 and 5 brownish. Metaleg: coxa brownish; trochanter simple, brownish; femur yellow with a broad ventrally interrupted diffuse brown annulus medially, basal part slightly concave dorsally, without black setae; tibia without apico-ventral tooth, brown, the basal 1/4 and an annulus on the apical 1/2 yellow; tarsus black. Abdomen. Length ratio of tergites I, II, III and IV 1:3.6:2.3:1.5. Tergites shiny brown to black; tergite III yellow on the anterior 1/3; tergite IV with anterolateral yellowish macula; the pile of tergites adpressed and pale, becoming longer towards the lateral margin; tergite I with 3 black and strong setae at lateral margin. Sternite IV ( Fig. 19 D) almost symmetrical, the pile pale; sternites VI–VIII simple, brown, the pile pale. Genitalia, Figs 19 A–C. Note the symmetrical surstyli and superior lobes, the very long curved aedeagal lobe and the long curved postero-dorsal part of aedeagus. FEMALE. Body length 4.8–6.0 mm, wing length 4.5–6.1 mm. Similar to male except for the normal sexual dimorphism. Face strongly concave, moderately projected antero-ventrally; frontal prominence well developed. Width of vertex at anterior ocellus:width of head 1:2.9; depth of the occipital fossa less than 1/4 of the width of an eye in dorsal view [1:3.3]. Width of face:width of head 1:3.2. Face ventrally yellow, rather shiny, dorsally black, pale pollinose. Gena shiny yellow. Frons and vertex shiny dark brown; frons with a pale-pollinose fascia just behind the frontal prominence which is narrowly interrupted in the middle; the pile short, erect and pale. Occiput shiny black. Antenna brownish-yellow; basoflagellomere elongated, ratio of length:width 1:0.7; arista short pilose. Length ratio of tergites I, II, III and IV 1:2.7:2.2:1.5. Ratio of length:width of tergites III and IV 1:1.2 and 1:1.8. Tergites I–III shiny black except for tergite III having yellow medial semiround or oval macula at anterior margin, tergites IV–VI yellow, tergite IV obscured antero-laterally. Tergite I with 2 dark-brown setae posteriorly at lateral margin. Sternite IV brownish, rectangular with at most slightly arcuate posterior margin, with pale pile; sternite V rectangular, nearly as long as wide, with long pale pile posteriorly.

Type material. HOLOTYPE. ♂, N.E. Burma, Kambaiti, 7000 ft., 14.v.1934, R. Malaise ( SMNH). PARATYPES. 1♂ with same data as holotype except 15.v. ( NBC); 1♀ with same data except 7.vi. ( BMNH); 1♀ with same data except 2000 m., 24.v. ( NBC).

Etymology. The name is composed of the Latin words crux, cross, and vena, vein, referring to the unusual cross vein between R1 and R2+3.

Discussion. Sphegina crucivena is very similar to S. forficata . Except for the characters mentioned in the key they differ by the following characters in the male genitalia: 1) in S. crucivena the dorsal margin of surstylus is bowed at the middle (in S. forficata the dorsal margin is evenly curved from base to apex), superior lobe is large, as long as sternite IX (small, one fourth of the length of sternite IX) and apex (posterior part) of the ejaculatory hood is simple (with tooth-like subapical lobe). The vestiture on the male sternite IV is also slightly different, in S. crucivena the pile medially at posterior margin being stronger than in the other parts while in S. forficata the pile is similar throughout.

Figures

FIGURE 2. Wing. A. Sphegina (Sphegina) uncinata sp. n. (paratype). B. S. (Asiosphegina) furva sp. n. (paratype). C. S. (A.) nasuta sp. n. (paratype). D. S. (A.) crucivena sp. n. (paratype). E. S. (A.) crassispina sp. n. (paratype). F. S. (A.) bidens sp. n. (paratype). G. S. (A.) carinata sp. n. (paratype). H. S. (A.) index sp. n. (paratype). I. S. (A.) simplex sp. n. (paratype). Scale 0.5 mm.

FIGURE 19. Sphegina (Asiosphegina) crucivena sp. n. (A, C holotype, B, D paratype). A. Left surstylus, lateral view. B. Right cercus, lateral view. C. Genitalia, lateral view. D. Sternite IV, ventral view. Scale 0.5 mm.