Dixella shannoni (Lane)

Huerta, Heron & Ibáñez-Bernal, Sergio, 2021, A new species of Dixella, the first Mexican record of Dixella shannoni, and a summary of dixid records from Mexico (Diptera: Dixidae), Zootaxa 5016 (3), pp. 430-440 : 438

Dixella shannoni (Lane)

( Figs. 3C , 8 , 9 )

Dixa (Dixella) shannoni Lane, 1942: 88 . (male; figs.; Costa Rica). Type-locality: San Mateo, Higuito, Costa Rica. Holotype male (USNM). Lane, 1953: 51 (male; description; distribution; figs.; Costa Rica).

Dixella shannoni (Lane) : Stone, 1966: 10.2 (Catalogue of Diptera of the Americas south of US); Chaverri & Borkent, 2007: 11 (male, female; diagnosis; redescription; distribution; bionomics; figs.; Costa Rica); Greewalt & Moulton, 2016: 31 (morphological data matrix).

Remarks. This species was previously known only from Costa Rica ( Lane, 1942, 1953; Chaverri & Borkent, 2007). We examined two males from Oaxaca, collected in the vicinity of Yaveo ( Fig. 9 ). Based on the descriptions provided by Lane and Chaverri & Borkent, our specimens are conspecific. Dixella shannoni is distinguished from other species of the genus by the following combination of characteristics: 1) a wide pale medial band on the pleura extending from the anterior margin of the katepisternum to the posterior margin of the anepimeron ( Fig. 8A ); 2) R 2+3 originating distal to r-m ( Fig. 3C ); 3) and 4) aedeagus triangular anteriorly (in Fig. 8B , it seems short and rounded because the position of terminalia after the permanent slide was made), aedeagal apodemes long with apical portion hook shaped (labeled as parameres in Fig. 11A of Chaverri & Borkent (2007)), parameres blade like ( Fig. 8B ). Our specimens from Mexico agrees with the general body description and structures of the male genitalia, differing only by the scutum being darker. This species was collected at altitudes of 180–700 m in Costa Rica ( Chaverri & Borkent, 2007), and in Mexico was collected at an altitude of 440 m.

New records for Mexico. Oaxaca, Santiago Yaveo ( Fig. 9 ), trap CDC, GPS: 17° 20’ 8.5” N, 95° 41’ 38” W; 20 Nov. 2019 , coll. entomological brigade, 2 males (slides, in CAIM) .

Distribution. Mexico (Oaxaca), Costa Rica.

Figures

FIGURE 3. Wing, dorsal view. A. Male, Dixella atitla sp. nov. B. Female, Dixella atitla sp. nov. C. Male, Dixella shannoni. Abbreviations: C= costal vein; CuA= anterior branch of cubital vein; CuP= posterior branch of cubital vein; M 1 = first branch of media; M 2 = second branch of media; M 3 + 4 = third and fourth branch of media;; m-cu= medial-cubital crossvein; m-m= medial crossvein; Rs= radial sector; R 1 = anterior branch of radius; R 2 = upper branch of second branch of radius; R 3 = lower branch of second branch of radius; R 2+3 = second branch of radius; R = third branch of radius; r-m= radial-medial crossvein; Sc = sub4+5 costal vein. Scale = 0.5 mm.

FIGURE 8. Dixella shannoni. A. Thorax, lateral view. B. Male genitalia, ventral view. Scale: A= 0.5 mm, B= 0.1 mm.

FIGURE 9. Distribution in Mexico of Dixella shannoni in state of Oaxaca.