Dixella venezuelensis Lane, 1942: 91
1953:50
Edwards, 1932:15
The Meniscus midges of Costa Rica (Diptera: Dixidae)
Chaverri, Luis Guillermo
Borkent, Art
Zootaxa
2007
2007-09-05
1575
1
1
34
3726K
Lane
Lane
[151,481,1277,1303]
Insecta
Dixidae
Dixella
Animalia
Diptera
17
18
Arthropoda
species
venezuelensis
( Figures 1G, 3A, 5A, 6G, 8C, 13A, 16A, 19B)
Dixella venezuelensis Lane, 1942: 91; 1953:50. Type-locality: Maracay, Venezuela. Holotypemale (BMNH). Dixellasp. Edwards, 1932:15. Unnamed larva and pupa.
Diagnosis. Male and female: only species of Dixidaein Central America with a round brown spot on the anepimeron ( Fig. 5A). Also only species of Dixidaein Central America with a short stem of R2+3. ( Fig. 6G).
Description. Male. Head( Fig. 1G): brown, with scattered spicules. Clypeus yellowish, 1.5 – 2.0 longer than basal width. Antennal scape, pedicel brown, flagellomeres yellowish. Thorax( Fig. 3A, 5A): scutum with brown medial vittae extending from anterior margin to beyond middle of scutum, narrow medially, invaginated posteriorly; lateral brown vitta extending from supraalar area to prescutal suture; medial, lateral vittae not joined anteriorly. Scutellum yellowish, mediotergite brown. Pleura with ventral half of katepisternum, posterior anepisternum, mesomeron brown, with conspicuous round brown spot on anepimeron; with 2– 3 setae on posteroventral margin of posterior anepisternum. Wing( Fig. 6G; Table 1): without dark spot over rm; R2+3 originating distal to r-m; stem of R2+3 short, less than 0.20 length of R3. Halter:pale, 0.50 length of fore femur. Legs: coxae, trochanters yellowish; femora yellowish with apical portion brown; claws as figured ( Fig. 8C). Genitalia( Fig. 13A): tergite 9 with anterior, posterior margins nearly straight, with about 3 submedial setae, about 5 on lateral margin. Sternite 9 with posterior margin with broad but very shallow exca- vation, with 5 one submedial, two lateral setae. Gonocoxite broader than long; basal lobe not visible; apical lobe as long as half gonostylus length, tip curved posteriorly, with elongate basal seta, elongate midlength seta, two short subapical setae. Gonostylus twice gonocoxite length, slightly curved, densely spiculate, apex blunt. Apparent paramere slender, extremely pale. Aedeagus somewhat rounded posteriorly, with numerous spicules. Tergite 10, broad (exact shape uncertain due to the structure being pale), narrow posteriorly, with elongate submedial seta. FIGURE 10.Genitalia of male Dixella, dorsal view. (A) D. maculata; (B) D. hernandezi. FIGURE 11.Genitalia of male Dixella, dorsal view. (A) D. shannoni; (B) D. hansoni. Female. As for male, with following differences: Wing( Table 2). Genitalia( Fig. 16A): sternite 8 1.25 longer than width of posterior margin, yellowish anteriorly, brown posteriorly, posteromedial area with elongate setae in irregular rows, posterior margin slightly concave; tergite 9 yellowish, posterolateral margin not pronounced posteriorly; sternite 9 wide, anterior margin irregular, truncate medially; segment 10 slightly shorter than cercus, posterolateral margin acute, with two elongate setae; cercus yellowish, slightly wider at base. Pupa. As described by Edwards (1932:15; as unnamed Dixellafrom Venezuela; Lane (1942:93; 1953: 50). Larva: As described by Edwards (1932:15; as unnamed Dixellafrom Venezuela; Lane (1942:93; 1953: 51).
Distribution and bionomics.This species is known from Costa Ricaand Venezuela( Fig. 19B). In Costa Rica, specimens were collected with an aerial net along the margin of a narrow stream where pools had formed, at 340 m, during the dry season (February), in a life zone corresponding to Premontane Wet Forest. They were collected together with an adult male D. woodi. The typelocality at Maracay, Venezuelais at 68 m. Taxonomic discussion.The male and female of this species were associated by their similar pigmentation pattern and were collected together in the same habitat. The internal structures of the male genitalia are pale in this species and we were only able to identify the parts with difficulty. The exact shape of sternite10 may be incorrect because it was pale and difficult to discern. Several features of D. venezuelensisare unique in Central America: R2+3 has a short base, the clypeus is very elongate, the scutellum is yellow and contrasting with the dark mediotergite (Lane’s postnotum) and the dorsal portion of the anepimeron had a distinctive dark spot (Lane’s mesepimeron). Lane described the male holotype, female allotypeand two maleand two female paratypes.. We examined the holotype, allotypeand one maleand one female paratype. It is uncertain where the remaining two paratypesare located. All type specimens were originally on pins (with the genitalia of the male paratypeplaced in balsam on a celluloid strip) and are now on slides. The type specimens were labeled “ venesuelensisEds., 1941” even though Lane (1942)named this species D. venezuelensisas a new species. Types. Holotype, male adult on microscope slide, labeled “Holotipo”, “ Dixella( Dixella) venesuelensisEds. 1941", “Maracay, Ven., July 15, 1927, No. DI”, “ Venezuela F.M. Root, B.M. 1931. 217”, “ Holotype” ( BMNH). Allotype, on microscope slide, labeled as for holotype( BMNH). Paratype: 1♂, 1 ♀, Higuito, San Mateo, Costa Rica, Pablo Schild( USNM). Other material: 6♂, 2 ♀, on microscope slides, Costa Rica, Prov. San José, Tarrazú, San Carlos, Reserva Riosparaíso, orilla del Río Blanco, 16 kmNE de Quepos, 340 m, 15- 17-II-2003, A. Borkent, CD 5400, LN 172094 522815 ( 4♂, 1 ♀, INBC; 3♂, 1 ♀, CNCI). Derivation of specific epithet.This species is named for the country where the typelocality is situated.
1927-07-15
BMNH
F. M. Root
Venezuela
Venezuela
20
21
2
holotype
[283,1045,1114,1140]
BMNH
Venezuela
20
21
2
allotype
USNM
Costa Rica
Pablo Schild
Higuito
San Mateo
20
21
2
1
1
paratype
LN 172094
2003-02-15
2003-02-17
2003-02-15
INBC, CNCI
A. Borkent
Costa Rica
Tarrazu
340
Reserva Riosparaiso
San Carlos
20
21
9
2
7
San Jose