Cerodontha (Dizygomyza) nigrihalterata, Boucher, Stéphanie, 2005

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 : 3-4

Cerodontha (Dizygomyza) nigrihalterata sp. nov.

( Fig. 1–7 )

Type material: Holotype. Male. COSTA RICA: Puntarenas: Golfito, R.F. Golfo Dulce, Estación Agujas, Sendera Ajo, 250– 350m. 2 Nov 1998. M. Umana. Manual. L_S_276750_526550 #56934, INB0003308651( INBIO)

Paratypes. COSTA RICA: Puntarenas: Est. Agujas. Send. Elvia. 300m. 3 Nov 1998. J. Matarrita, I. Lopez, J. Gutierrez. L_S_276750_526550 #51810 INB0003021049 (1M, INBIO); Golfito, R.F. Golfo Dulce, Estación Agujas, Sendera Ajo, 250– 350m. 2 Nov 1998. M. Umana. Manual. L_S_276750_526550 #56934, INB0003308650 (1F, INBIO); same except INB0003308658 (1M, INBIO); 3 km SW of Rincon, 9°55’N, 84°13’W, 10m, Oct–Dec 1990, malaise trap, P. Hanson (1F, USNM); R.F. Golfo Dulce, 5km W Piedras Blancas, 100m, malaise trap, x.1991, P. Hanson (1F, LEM); Peninsula Osa, 23 km N Pto. Jimenez, La Palma, 10m, Malaise trap, x–xi.1990, P. Hanson (1F, LEM); Cartago: Turrialba, vii­15 ­19.1965, P.J. Spangler (1M, USNM).

Diagnosis. This species can be differentiated from all other Cerodontha (Dizygomyza) species by the combination of the following characters: black halter, the presence of only one ors and wings conspicuously infuscated in cell r1 and r2+3.

Description. Head including antenna, brown, gena paler, yellowish­brown; epistoma and facial ridge yellowish. Thorax uniformly brown, calypter including margin white, fringe brown. Halter completely brown. Legs brown, except foreknee and tarsi pale yellow. Abdomen brown.

Frons width 0.35–0.40 mm; ratio of frons width to eye width 1.6–1.8; orbit broad, 0.22–0.27 width of frons at midpoint; orbit widening anteriorly ( Fig. 6 ); frons projecting above and in front of eye in profile, orbit forming only narrow ring below eye; eye slightly pubescent; lunule and anterior margin of orbit with patch of silvery pubescence best seen in posterodorsal view; orbit and ocellar triangle shining; frons with microtomentum; usually 3 ori and 1 ors (one aberrant specimen with 3 ors, including one displaced medially at margin of orbit and frons) anterior ori a little shorter than other ori; first 2 anterior ori inclinate; posterior ori reclinate and slightly lateroclinate; ors reclinate and slightly inclinate; 4–5 reclinate and/or inclinate orbital setulae, short, normal, in one row, present anteriorly (not reaching ors); first flagellomere slightly enlarged in male with white pubescence on lateral surface and black pubescence on medial surface, extent of white pubescence variable; first flagellomere in female with black pubescence apically and medially; arista longer than eye height with long pubescence; arista white basally in some specimens, not obviously swollen at base; gena with uniform width; gena height 0.20–0.25 times eye height; lunule broad, in the form of a semicircle, or a little higher, upper margin reaching level of first or second ori; bases of antennae widely separated. Three postsutural dc, anterior postsutural 0.57–0.70 times length of second postsutural; presutural dc absent; acrostichals irregular in 7–8 rows; prsc absent; one postsutural intra­alar; 1 presutural and two postsutural supra­alar; notopleuron with 2 bristles on ventral side. Midtibia with strong apico­ventral bristle, almost half as long as first tarsomere; no other bristles on fore or mid tibiae. Wing length 1.9–2.1 mm in males and 1.8–2.0 mm in females; R4+5 ending a little closer to wing tip than M1+2; costa extending to M1+2; wing conspicuously infuscated in cell r1 and r2+3 ( Fig. 7 ); cross­vein dm­cu present; second costal sector 3.8–4.7 times length of fourth; last section of CuA1 short: 0.48–0.56 times length of penultimate. Crossvein r­m located at 0.3–0.4 the length of cell dm.

Male genitalia. Distiphallus with tubules mostly parallel sided, slightly dilated at apex ( Fig. 1, 2 ). Hypandrium broad and rounded ( Fig. 1 ). Surstylus with patch of strong bristles at medioventral margin ( Fig. 3 ). Ejaculatory apodeme with narrow base and moderately enlarged at apex ( Fig. 4 ). Anal projection of epandrium prominent ( Fig. 5 ).

Derivation of Species Name. The species name refers to the black halteres of this species.

Comments. The conspicuously infuscated cells r1 and r3+ 4 in the wings and the presence of only one ors are unique characters among New World Dizygomyza . However, the dark halter is also present in Cerodontha inepta (Spencer) a species known from Brazil ( Spencer 1963). That species was originally placed in the subgenus Poemyza and was later transferred to Dizygomyza ( Spencer 1966) . But according to the description of the lunule (high and narrow, upper margin above level of upper ori) it seems that this species does not belong in the subgenus Dizygomyza . Unfortunately the species is known from a female specimen only. Other than the higher lunule, Cerodontha inepta differs externally from Cerodontha (D.) nigrihalterata by having 2 ori and 3 ors, orbital setulae unusually long, last section of CuA1 only slightly shorter than penultimate in ratio 20:22, wing only slightly brownish, and stalk of halter yellowish.

Figures

FIGURES 1 – 7. Cerodontha (Dizygomyza) nigrihalterata sp. nov. 1, phallus with hypandrium, ventral view; 2, phallus lateral view; 3, subepandrial sclerite and surstylus (ventral, left); 4, ejaculatory apodeme; 5, epandrium lateral view showing anal projection (ap); 6, head dorsal view; 7, wing.