Cerodontha (Dizygomyza) scirpioides Zlobin 1997

Boucher, Stéphanie, 2005, Description of an unusual new Costa Rican species of Cerodontha (Dizygomyza) with additional notes on Neotropical species of Dizygomyza (Diptera: Agromyzidae), Zootaxa 993, pp. 1-8 : 6-7

Cerodontha (Dizygomyza) scirpioides Zlobin 1997

( Figs. 13–17 )

Description. Head completely brown including antenna; inner margin of orbit yellowish. Thorax uniformly brown; calypter whitish on basal portion, but pale brown on apical portion, margin and fringe brown; halter white. Legs brown, except foreknee yellow.

Frons width 0.35mm (male) – 0.39mm (female); ratio of frons width to eye width 1.5 (female) – 1.9 (male); orbits parallel sided, 0.18 width of frons at midpoint; frons only slightly projecting above eye in profile; frons mat with black microtomentum; orbit moderately shining; 2 inclinate ori, lower ori 0.66 length of upper ori; and 2 ors, upper strong and reclinate, lower weak, lateroclinate, 0.27 (female) – 0.55 (male) the length of upper ors; first flagellomere enlarged in male, strongly pubescent; pubescence not as strong in female and most easily seen on apical portion of first flagellomere; arista as long as eye height with distinct pubescence; gena slightly extended at rear; gena height 0.10 (female) – 0.13 (male) times eye height at midpoint; lunule with silvery pubescence; lunule broad, in the form of a semicircle; bases of antennae widely separated. Three postsutural and 1 presutural dc; acrostichals in 6 rows; prsc present, but weak; anepisternum with 1 strong and 5–6 medium sized bristles along posterior margin. Wing length 2.1mm (male) – 2.9mm (female) mm; wing tip at midpoint between M1+2 and R4+5; costa extending to M1+2; crossvein dm­cu present; last section of CuA1 0.65 (female)–0.68 (male) times length of penultimate; cross­vein r­m slightly before midpoint of cell dm.

Male genitalia. Distiphallus approximately same length as mesophallus. Tubules parallel sided and diverging in ventral view ( Fig. 13 ). Surstylus with a row of small to moderately long spines anteriorly and 2 long but weak bristles on lower margin ( Fig. 15 ). Epandrium with patch of medial posteroventral spines ( Fig. 15 ). Anal projection of epandrium prominent ( Fig. 16 ). Ejaculatory apodeme not greatly enlarged ( Fig. 17 ).

Comments. This species is easily distinguished from other Nearctic species by the presence of one strong upper ors and one much reduced lower ors. The species was originally described from Durango, Mexico. Additional specimens from Chiapas, Mexico ( MEXICO: Chiapas, San Critobal 7000’, 15.v.1969, H.J.Teskey, 1 female, CNC) and Cartago, Costa Rica ( COSTA RICA: Cartago, Dulce Nombre, Vivero Linda Vista 1400m, Malaise trap, vi–viii.1993, P. Hanson, 1 male, LEM) on which the above description is based apparently belong to this species. Although there are slight differences in external characteristics (gena height relative to eye height, wing length, color of calypter and fringe) and shape of genitalia of these specimens (distiphallus not as dilated in lateral view, and generally narrower, parallel sided in ventral view), these specimens are placed in C. (D.) scirpioides until more specimens become available to confirm possible variation of the species.

Figures

FIGURES 13 – 17. Cerodontha (Dizygomyza) scirpioides Zlobin. 13, phallus ventral view; 14, phallus lateral view; 15, epandrium with surstylus (ventral, left) 16, epandrium lateral view showing anal projection (ap); 17, ejaculatory apodeme.