Dixella venezuelensis Lane

Chaverri, Luis Guillermo & Borkent, Art, 2007, The Meniscus midges of Costa Rica (Diptera: Dixidae), Zootaxa 1575 (1), pp. 1-34: 18-21

publication ID

http://doi.org/ 10.11646/zootaxa.1575.1.1

publication LSID

lsid:zoobank.org:pub:6D448CFC-0B62-46C0-92BF-24629AE3FCE0

persistent identifier

http://treatment.plazi.org/id/03A187C6-FF95-FF92-4EF8-FB59FA65FA84

treatment provided by

Felipe

scientific name

Dixella venezuelensis Lane
status

 

Dixella venezuelensis Lane  

( Figures 1G View FIGURE 1 , 3A View FIGURE 3 , 5A View FIGURE 5 , 6G View FIGURE 6 , 8C View FIGURE 8 , 13A View FIGURE 13 , 16A View FIGURE 16 , 19B View FIGURE 19 )

Dixella venezuelensis Lane, 1942: 91   ; 1953:50. Type-locality: Maracay, Venezuela. Holotype male (BMNH).

Dixella sp.   Edwards, 1932:15. Unnamed larva and pupa.

Diagnosis. Male and female: only species of Dixidae   in Central America with a round brown spot on the anepimeron ( Fig. 5A View FIGURE 5 ). Also only species of Dixidae   in Central America with a short stem of R2+3. ( Fig. 6G View FIGURE 6 ).

Description. Male. Head ( Fig. 1G View FIGURE 1 ): brown, with scattered spicules. Clypeus yellowish, 1.5 – 2.0 longer than basal width. Antennal scape, pedicel brown, flagellomeres yellowish. Thorax ( Fig. 3A View FIGURE 3 , 5A View FIGURE 5 ): 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 View FIGURE 6 ; 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 View FIGURE 8 ). Genitalia ( Fig. 13A View FIGURE 13 ): 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.

Female. As for male, with following differences: Wing ( Table 2). Genitalia ( Fig. 16A View FIGURE 16 ): 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 Dixella   from Venezuela; Lane (1942:93; 1953: 50).

Larva: As described by Edwards (1932:15; as unnamed Dixella   from Venezuela; Lane (1942:93; 1953: 51).

Distribution and bionomics. This species is known from Costa Rica and Venezuela ( Fig. 19B View FIGURE 19 ). 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 type locality at Maracay, Venezuela is 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. venezuelensis   are 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 allotype and two male and two female paratypes .. We examined the holotype, allotype and one male and one female paratype. It is uncertain where the remaining two paratypes are located. All type specimens were originally on pins (with the genitalia of the male paratype placed in balsam on a celluloid strip) and are now on slides. The type specimens were labeled “ venesuelensis Eds., 1941   ” even though Lane (1942) named this species D. venezuelensis   as a new species.

Types. Holotype, male adult on microscope slide, labeled “Holotipo”, “ Dixella (Dixella) venesuelensis Eds. 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 km NE de Quepos, 340 m, 15- 17-II-2003, A. Borkent, CD 5400, LN 172094 View Materials 522815 (4♂, 1 ♀, INBC; 3♂, 1 ♀, CNCI)   .

Derivation of specific epithet. This species is named for the country where the type locality is situated.

USNM

Smithsonian Institution, National Museum of Natural History

INBC

Instituto Nacional de Biodiversidad (INBio)

CNCI

Canadian National Collection Insects

Kingdom

Animalia

Phylum

Arthropoda

Class

Insecta

Order

Diptera

Family

Dixidae

Genus

Dixella

Loc

Dixella venezuelensis Lane

Chaverri, Luis Guillermo & Borkent, Art 2007
2007
Loc

Dixella venezuelensis

Lane, J. 1953: 50
Lane, J. 1942: 91
1942
Loc

Dixella sp.

Edwards, F. W. 1932: 15
1932