Dixella jironi Chaverri and Borkent, 2007

Chaverri, Luis Guillermo & Borkent, Art, 2007, The Meniscus midges of Costa Rica (Diptera: Dixidae), Zootaxa 1575 (1), pp. 1-34 : 17-18

Dixella jironi Chaverri and Borkent n. sp.

( Figures 1F , 6F , 8B , 12B , 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 and with the gonostylus apically tapered ( Fig. 12B ). Female: unknown.

Description. Male. Head ( Fig. 1F ): brown, densely spiculate, with spicules more elongate than those in D. shannoni , D. hansoni , D. fernandezae . Clypeus yellowish, as wide as long. Antennal scape, pedicel, flagellomeres yellowish. Thorax: similar to D. shannoni ( Fig. 2C , 4C ). Scutum yellowish, with narrow lateral light brown band extending from anterior margin, widening near prescutal suture, continuing laterally to supraalar area, anterior to middle of scutum lateral band continues medially as faint yellow line, with row of setae to prescutellar area; acrostical, anterior dorsocentral, supraalar setae short, scattered. Scutellum, mediotergite brown. Pleura with 2 setae on posteroventral margin of posterior anepisternum. Wing ( Fig. 6F ; Table 1): with or without slight darkening over r-m; R2+3 originating either at or slightly distal to r-m; stem of R2+3 0.40 length of R3. Halter: pale, 0.40 length of fore femur. Legs: yellowish; claws as figured ( Fig. 8B ). Genitalia ( Fig. 12B ): tergite 9 with anterior, posterior margins curved, with setae more dense along posterior margin. Sternite 9 with posterior margin with moderately narrow excavation, with 3–4 posterolateral setae. Gonocoxite longer than wide; basal lobe quadrate; apical lobe cylindrical, tusk-like, slightly curved dorsally, tip rounded, 0.6 length of gonostylus, with elongate basal seta, midlength seta as long as half lobe length, two short subapical setae. Gonostylus slightly wider at base and apex, apex rounded, with short subapical seta. Parameres dark brown, narrow, sinuous, pointed, apices directed posteriorly. Aedeagus triangular. Tergite10 light brown, posterior margin slightly bilobed, with four short subapical setae.

Female and immatures. Unknown.

Distribution and bionomics. Dixella jironi is known only from the type locality in Costa Rica at 1700 m ( Fig. 18B ). Adults were swept from low vegetation near a small stream at the beginning of rainy season (May) in a habitat corresponding to Premontane Moist Forest.

Taxonomic discussion. The male adult of this species shares the medial pale band on the thoracic pleura of D. shannoni and D. hansoni . The apical lobe of the gonocoxite of the male genitalia is similar in the three species but in D. jironi it is longer, relative to the gonostylus. Further differences are present in the shape of the parameres, gonostyli and the tenth sternites of these three species (see key, Figs. 11A, B , 12B ).

Types. Holotype, male adult on microscope slide, labeled “ HOLOTYPE Dixella jironi Chaverri and Borkent ”, “ Costa Rica, San José, Escazú, Alto Tapezco , 1700 m, 31-V-1999, A. Borkent, LN 209100 518900” ( CNCI) . Paratypes: 3♂ on microscope slide (1♂, INBC; 2♂, CNCI) .

Derivation of specific epithet. This species is named for Luis Fernando Jiron, a former entomology professor at the Universidad de Costa Rica who has published extensively on fruit flies ( Diptera : Tephritidae ) and who was a student advisor 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 8. Claws of male Dixella. (A) D. fernandezae; (B) D. jironi; (C) D. venezuelensis.

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

FIGURE 12. Genitalia of male Dixella, dorsal view. (A) D. fernandezae; (B) D. jironi.

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— .