Dixella hansoni Chaverri and Borkent, 2007

Chaverri, Luis Guillermo & Borkent, Art, 2007, The Meniscus midges of Costa Rica (Diptera: Dixidae), Zootaxa 1575 (1), pp. 1-34 : 13-15

Dixella hansoni Chaverri and Borkent n. sp.

( Figures 1D , 2D , 4D , 6D , 7D , 11B , 18B )

Diagnosis. Male: only species of Dixidae in Central America with a wide pale medial band on the pleura extending from the anterior margin of the katepisternum to the posterior margin of the anepimeron ( Fig. 4D ), with R2+3 originating distal to r-m (fig. 6D), and with the aedeagus bilobed anteriorly ( Fig. 11B ). Female: unknown.

Description. Male. Head ( Fig. 1D ): brown, densely spiculate. Clypeus brown, as wide as long. Antennal scape, pedicel brown, flagellomeres yellowish. Thorax ( Fig. 2D , 4D ): scutum yellowish, broad anterolateral brown line narrowing posterolaterally; lateral band continues medially as faint yellow line anterior to middle of scutum to prescutellar area, with single row of elongate setae; acrostical, anterior dorsocentral, supraalar setae short, scattered. Scutellum brown, mediotergite yellowish. Pleura with pronotum yellowish, propleuron, katepisternum, posterior anepisternum, anepimeron, metanepisternum brown; medial yellow strip extending from katepisternum to anterior half of anepimeron; 2 setae on posteroventral margin of posterior anepisternum. Wing ( Fig. 6D ; Table 1): with or without slight darkening over r-m; R2+3 originating distal to r-m; stem of R2+3 0.55 length of R3. Halter: pale, 0.45 length of fore femur. Legs yellowish; claws as figured ( Fig. 7D ). Genitalia ( Fig. 11B ): tergite 9 with anterior, posterior margins nearly straight, with scattered setae, more sparse medially. Sternite 9 with posterior margin with broad excavation, with one submedial, two lateral setae. Gonocoxite as long as wide; basal lobe rounded, medial margin somewhat rounded; apical lobe cylindrical, tusk-like, slightly curved dorsally, tip acute, 0.50 length of gonostylus, with elongate basal seta, elongate midlength seta, two short subapical setae. Gonostylus slightly swollen at base, apex not swollen, subapical spine not present. Parameres dark brown, narrow, each curved in S shape, apices convergent. Aedeagus as figured. Tergite 10 light brown, anterolateral margin rounded, posterior margin somewhat bilobed, with 1–2 short subapical setae, subbasal lateral brown membrane.

Female and immatures. Unknown.

Distribution and bionomics. Dixella hansoni is known from a single male in Costa Rica ( Fig. 18B ), collected at 10 m elevation during the dry season (January). The specimen was swept from the margin of either Quebrada Bonita or a small tributary of this stream. The habitat corresponds to Tropical Moist Forest in the lowlands.

Taxonomic discussion. This species is similar to D. shannoni but the medial strip of paler cuticle on the pleura extends posteriorly only to about the anterior half of the anepimeron, the tarsal claws differ in number of teeth, the tip of the apical lobe of the male genitalia is rounded in D. shannoni and acute in D. hansoni , the gonostylus in D. hansoni lacks apical setae, and tergite 10 differs in shape and number of setae in both species. A single female collected from the type locality but on 24-I-1994 (INBC) may represent the female of D. hansoni . However, we were unable to discern any difference between this female and those of D. shannoni and, with the information available, it may belong to either species.

Types. Holotype, male adult on microscope slide, labeled “ HOLOTYPE Dixella hansoni Chaverri and Borkent ”, “ Costa Rica, 2 Km NE Tárcoles, Carara NP, 1-I-1994, A. Borkent, CD 1726” ( CNCI).

Derivation of specific epithet. This species is named for Paul E. Hanson in recognition of his important and continuing research on the Hymenoptera and other insects of Costa Rica and for his invaluable teaching of entomology to the first author.

Figures

FIGURE 1. Head capsules of male Dixella, anterior view. (A) D. maculata; (B) D. hernandezi; (C) D. shannoni; (D) D. hansoni; (E) D. fernandezae; (F) D. jironi; (G) D. venezuelensis; (H) D. woodi; (I) D. lobata; (J) D. suzukii.

FIGURE 2. Thoraces of male Dixella, dorsal view. (A) D. maculata; (B) D. hernandezi; (C) D. shannoni; (D) D. hansoni.

FIGURE 4. Thoraces of male Dixella, lateral view. (A) D. maculata; (B) D. hernandezi; (C) D. shannoni; (D) D. hansoni.

FIGURE 6. Wings of male Dixella. (A) D. maculata; (B) D. hernandezi; (C) D. shannoni; (D) D. hansoni; (E) D. fernandezae; (F) D. jironi; (G) D. venezuelensis; (H) D. woodi; (I) D. lobata; (J) D. suzukii.

FIGURE 7. Claws of male Dixella. (A) D. maculata; (B) D. hernandezi; (C) D. shannoni; (D) D. hansoni.

FIGURE 11. Genitalia of male Dixella, dorsal view. (A) D. shannoni; (B) D. hansoni.

FIGURE 18. Distributions of Dixella species in Costa Rica: (A) D. maculata—O; D. hernandezi–-#, D. shannoni— ; (B) D. hansoni—O, D. fernandezae—#, D. jironi— .