Dixella suzukii Chaverri and Borkent, 2007

Chaverri, Luis Guillermo & Borkent, Art, 2007, The Meniscus midges of Costa Rica (Diptera: Dixidae), Zootaxa 1575 (1), pp. 1-34 : 28-30

Dixella suzukii Chaverri and Borkent n. sp.

( Figures 1J , 3D , 5D , 6J , 9C , 14B , 17, 19B )

Diagnosis. Male: only species of Dixidae in Central America with a short, conical gonostylus ( Fig. 14B ). Female: only species of Dixidae in Central America with a short lobe protruding from the lateral margin of abdominal segment 10 ( Fig. 17).

Description. Male. Head ( Fig. 1J ): brown, densely spiculate. Clypeus brown, as wide as long. Antennal scape, pedicel brown, flagellomeres yellowish. Thorax ( Fig. 3D , 5D ): scutum with wide dark brown medial vitta extending from anterior margin to middle of scutum, continuing as lighter, narrower brown band to supraalar area; lateral dark brown vitta broadly joined to medial vitta anteriorly near prescutal suture, extending to supraalar area, lateral margin notched above spiracular area. Scutellum, mediotergite dark brown. Pleura dark brown, somewhat patterned, except pronotum yellowish, katepisternum with yellow area on posterior margin. Wing ( Fig. 6J ; Table 1): with slight darkening over r-m; R2+3 originating at or distal to r-m; stem of R2+3 0.47 length of R3. Halter: pale, 0.30 length of fore femur. Legs: coxae, trochanters brown; femora yellowish with brown apices; tibiae, tarsi uniformly pale brown; claws as figured ( Fig. 9C ). Genitalia ( Fig. 14B ): tergite 9 with anterior margin somewhat concave, posterior margin straight, with numerous scattered setae. Sternite 9 with posterior margin with moderately broad excavation, with 5 elongate lateral setae. Gonocoxite as long as wide; basal lobe absent; apical lobe slightly longer than gonostylus, triangular apex with sharp ventral lobule and elongate dorsal lobule, stem with three elongate seta, one short subapical seta. Gonostylus densely spiculate, with elongate setae, broad basally, tapering gradually to apex. Parameres directed anteriorly, tips rounded, convergent. Aedeagus brown, elongate, narrow, directed posteriorly. Tergite 10 with narrow lateral band, posterolateral expansion, posteromedially with pair of protrusions.

Female. As for male, with following differences: Wing ( Table 2). Genitalia ( Fig. 17): sternite 8 with posterior margin concave medially, medial bulge with dense patch of setae, slightly wider posteriorly, with more setae than previous sternites; tergite 9 dark brown, posterolateral margin rounded, anteroventral margin notched; sternite 9 narrow, with sublateral ventral bulge; segment 10 as long as cercus, with scattered setae, with small basal protuberance; cercus short, slightly wider at base, with elongate setae.

Immatures: not described.

Distribution and bionomics. This species is known from two localities in Costa Rica and two localities in Panama ( Fig. 19B ) at 660–1585 m. In Costa Rica the habitat in which specimens were collected corresponds to Premontane Very Wet Forest. Larvae from the type locality were collected from a seepage pool with muddy substrate in a grazing area during the dry season (April). The male from 3 km E of Cambronero, Costa Rica was reared from a larva collected from a “wide shallow seepage from roadside bank in grazing area; water semipermanent, clear, with slow current; choked with grasses; bottom with mud, much dead grass; full sun” ( Heinemann and Belkin, 1977) during the rainy season (August). Adults from Panama were collected in light traps.

Taxonomic discussion. We studied males and females reared from identical larvae and pupae from the type locality, indicating that they are conspecific. Heinemann and Belkin (1977) recorded this species as Dixella sp. 1 with the following specimens in the USNM labled as such: CR 352-23 and 352-25. There are additional specimens of five associated larval and pupal exuviae labeled as Dixella sp. 1 which may conspecific with D. suzukii (CR352-20-22, 24, 26) but these were not associated with any adults and therefore are of uncertain identity.

Types. Holotype, male adult on microscope slide, labeled “ HOLOTYPE Dixella suzukii Chaverri and Borkent ”, “ Costa Rica, Cartago, Orosí, P.N. Tapantí-Macizo de La Muerte, orilla del puente del río Grande de Orosí , 1200 m, 27-IV-2001, B.H. Hernández, En charco, LN 259000 558850, BHB 470.30, larva and pupal exuviae associated” ( INBC) . Allotype, female adult on microscope slide labeled as holotype but with code BHB 470.36, ( INBC) . Paratypes: 5♂, 8 ♀, on microscope slides labeled as above but with codes BHB 470.13, BHB 470.14, BHB 470.38, BHB 470.22 (larva and pupal exuviae associated), BHB 470.35, BHB 470.05 (larva and pupal exuviae associated), BHB 470.12, BHB 470.21, BHB 470.37, BHB 470.24, BHB 470.27 (pupal exuviae associated), BHB 470.34, BHB 470 (3♂, 4 ♀, INBC; 1♂, 2 ♀, CNCI; 1♂, 2 ♀, USNM) ; 1♂, 1 ♀ on microscope slide, each with larval and pupal exuviae on separate microscope slides: Costa Rica, Alajuela, 12.7 km W of San Ramon on Natl. Rt. 1, about 3km E of Cambronero , 770 m, 13-VIII-1971, S.J. Heinemann ( USNM) ; 1♂ on microscope slide: Panama, Chiriqui, Chiriqui ViejoR. El Volcan 22-VII-1966, A. Broce, light trap ( USNM) ; 1 ♀ on microscope slide: Panama, David , Chiriqui, 24-VII-1964, A. Broce, light trap ( USNM) .

Derivation of specific epithet. We name this species suzukii to honour David T. Suzuki, a Canadian environmentalist who has devoted his life teaching the public about of the state of our earth and the importance of taking better care of our world.

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 3. Thoraces of male Dixella, dorsal view. (A) D. venezuelensis; (B) D. woodi; (C) D. lobata; (D) D. suzukii.

FIGURE 5. Thoraces of male Dixella, lateral view. (A) D. venezuelensis; (B) D. woodi; (C) D. lobata; (D) D. suzukii.

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 9. Claws of male Dixella. (A) D. woodi; (B) D. lobata; (C) D. suzukii.

FIGURE 14. Genitalia of male Dixella, dorsal view. (A) D. lobata; (B) D. suzukii.

FIGURE 19. Distributions of Dixella species in Costa Rica: (A) D. woodi—O, D. lobata—#; (B) D. venezuelensis—O, D. suzukii—#.