Drosophila pictiventris Duda 1925
Creators: name: Grimaldi, David A.
Publisher: name: Zenodo
Year: 2018
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Diptera
Drosophilidae
Drosophila
Drosophila pictiventris

description: Drosophila pictiventris Duda, 1925: 211.
DIAGNOSIS: Coloration distinctive, elaborate, with light, cream-colored areas and dark brown markings; frons and scutum dark brown, the latter with faint, light brown, pollinose stripes; pleura with three thick, dark brown stripes alternating with thinner, cream-colored areas; legs light with light brown fuscous areas; wing with crossveins slightly clouded; abdomen mostly dark brown, with light median stripe, tergites 2–6 with light lateral spots and tergites 2–4 with additional light spots near lateral margins. Basal flagellomere with short setulae, arista with relatively long branches, 8 dorsal, 1–2 ventral; face relatively deep (FD/FW 1.21), cheek shallow (CD/ED 0.11), wing relatively short (ThL/WL 0.50). Oviscapt with distal pegs differentiated (apical one largest, vertical row of three dorsal ones, with gap between them). Male: Epandrium with pair of very large, thick setae laterally; cercus flattened; aedeagus relatively short (only slightly longer than aedeagal apodeme), finely scaled on ventral surface; surstylus with lateral row of five peg prensisetae, plus numerous spinelike ones medially.
DESCRIPTION: Coloration: Head: Frons mostly dark brown, anterior margin and thin median stripe ochre; fronto-orbital plates slightly lighter than frontal vittae; ocellar triangle and surrounding margin dark black-brown; light spot at base of outer vertical seta. Antenna with scape light, pedicel and basal flagellomere dark brown. Face light fuscous, lighter on oral margin; vibrissal angle and spot under cheek dark brown, cheek light; palp dark brown, clypeus slightly lighter; proboscis yellowish. Eye dark, dull red. Occiput dark brown. Thorax: Scutum dark brown, with faint light brown, pollinose stripes; light stripes coalesce on anterior portion of scutum, extending about 3/4 length of scutum; one stripe is median, two lateral to this (just inside dorsocentrals); lateral light stripe with short branch diverges toward supra-alar seta. Scutellum largely dark brown; postpronotal lobe light. Pleura with 3 dark brown, diffuse stripes, alternating with thinner, light, cream-colored stripes: 1 dark stripe from anterior edge to wing base, just under notopleural suture; another through middle of pleura, beginning just behind procoxa; third dark stripe covering all of katepisternum, meron, and metepisternum. Legs: All coxae light, cream colored; femora, tibiae, and tarsi light, fuscous brown, with slightly darker portions on femur (prebasally and preapically). Wing: Hyaline, only marking being slight infuscate cloud over crossveins and near wing base; veins brown. Halter with knob light, cream colored; stem light brown. Abdomen: Tergites mostly dark brown, with light median stripe through at least tergites 1–6, with row of light spots laterally on tergites 2–6; light spots lateral to this row on tergites 2–4, these coalesced on tergites 2 and 3. Little or no sexual dimorphism in coloration.
Head: Antenna: Scape with row of 5–6 fine setulae; pedicel setulose, with two larger setae; basal flagellomere of moderate length, tip at level of end of carina, setulae short; arista with 6–8 dorsal, 2 ventral branches plus small terminal fork, dorsal branches relatively long. Eye with dense, short interfacetal setulae; oval in lateral view, posterior margin slightly flattened. Face slightly raised, same width as lower part of frons; carina narrow, length ca. 0.65× depth of face. Vibrissa well differentiated from subvibrissal setulae, 1 pair; subvibrissal setae small. Frons: Fronto-orbital plates velvety, microscopically striate; fronto-orbital setae slender, slightly shiny. Anterior reclinate, posterior reclinate, inner vertical setae in line; proclinate seta slightly medial to this line, anterior (not lateral) to anterior reclinate; anterior reclinate seta midway between other orbitals, ca 0.4× length of proclinate; posterior reclinate slightly closer to proclinate than to inner vertical. Ocellar setae extending to level of proclinates; postocellar setae ca. 0.7× length of ocellars, tips crossing at apical quarter. Inner vertical setae upright, slightly inclinate; outer vertical setae strongly lateroclinate, slightly longer than inner verticals. Clypeus narrow; palp relatively small, with single large, subapical seta; proboscis at rest almost fully retracted under head, labellum small and barely exposed. Cheek relatively shallow.
Head measurements (N = 4): CD/ED 0.11 (0.10–0.15), ED/EW 1.34 (1.27–1.40), FD/FW 1.21 (1.13–1.31), FL/LFW 0.94 (0.88–1.00), HW/ HD 1.35 (1.21–1.43), Ocellar S-index 1.33 (1.23– 1.50), OR1/OR3 1.04 (1.00–1.12), OR2/OR1 0.48 (0.38–0.66), VT-index 1.03 (1.00–1.15).
Thorax: Setation: Acrostichals in 6 rows, ones just anterior to transverse suture barely enlarged; anterior dorsocentral seta anterior to posterior dorsocentral by little more than length of anterior dorsocentral, slightly medial to posterior dorsocentral; anterior dorsocentral significantly finer than posterior dorsocentral. Anterior scutellars parallel, posterior scutellars crossed for about 0.5× their length. Postpronotal lobe with 2 short setae; 3 notopleural setae (1 dorsal, other 2 near notopleural suture); 1 short, 1 long supraalar setae; 1 short postalar seta. Anterior katepisternal significantly smaller than (ca. 0.5× the length) posterior katepisternal; two fine setulae between these.
Legs: Forefemur with row of 4 long setae on ventrolateral surface; mid- and hind femora without such setae. Foretibia without larger setae; midtibia with ventroapical seta, hind tibia with preapical dorsal seta. Male foretarsus with a few very short, erect setulae on dorsal surface.
Thorax and wing measurements (N = 4): ThL 0.94 mm (0.86–1.08), DC-index 0.50 (0.39–0.63), S-index 0.48 (0.48–0.51), 4-V index 1.95 (1.85– 2.00), 5-X index 1.82 (1.52–2.20), C-index 2.05 (1.87–2.36), hb-index 1.68 (1.53–1.84), ThL/WL 0.50 (0.49–0.51), WL/WW 2.19 (2.18–2.23).
Male Terminalia: Epandrium arched, rather broad, with lateral row of ca. 8 setae, ventralmost two setae very large and thick; ventral lobe of epandrium small, barely reaching to level of surstylus, with marginal row of ca. 6 fine setae. Small, slender sclerite isolated between ventral lobe of epandrium and surstylus (remnants of epandrium?). Cercus not connected to epandrium, slightly less sclerotized, with microtrichia; sparse fine setulae on flattened ventral margin. Subepandrial sclerite large, with pair of faintly sclerotized and granular anterior arms. Surstylus pendulous, with dorsolateral row of heavily sclerotized 14–15 prensisetae pegs; middle row of large, sharp, sclerotized prensisetae; numerous finer ones medially. Hypandrium well developed; pair of large setae on paraphysis, two pairs smaller ones; posterolateral lobes concave, finely wrinkled. Aedeagus relatively short, about same length as aedeagal apodeme, apex slightly bulbous, membranous, without scales; shaft with fine overlapping scales ventrally. Ejaculatory apodeme relatively small, broadest portion a slender oval, at an oblique angle to apodeme. Female Terminalia: Oviscapt short, broad, oviscapt pegs as follows: vertical row of 3 dorsally, gap between this row and large apical peg; horizontal row ca. 9 pegs near ventral margin, significantly decreasing in size anteriad. Oviprovector well developed but scales relatively small and sparse. Spermatheca moderately sclerotized, dome shaped, externally smooth (not annulate or wrinkled), introvert ca. 0.8× length of capsule.
TYPE: Holotype, female, labelled “Higuito-San Mateo, Costa Rica, Schild 914, VII.16, Drosophila busckii-ventris n. sp. Det. Dr. O. Duda; Drosophila pictiventris n. sp. Type F, det. Duda.” In HNHM, Budapest. The type specimen was examined by me in 2010, by Wheeler (1954, 1963), and by Bächli (1984), who mentioned (p. 34) that “According to DUDA, all species described in this 1925 paper should be labelled ‘ Suiza de Turrialba,’” which is another locality in Costa Rica where Schild extensively collected.
OTHER SPECIMENS EXAMINED: USA: Florida: Highlands Co., Lake Placid, Archbold Bio. Sta., M. Deyrup, emerged indoors 10 Oct. 1989 from Suillus sp. [Boletaceae], 6♂, 6♀ (1♂, 1♀ dissected, nos. 8, 9 respectively); emerged indoors 17 Oct 1989 from Clytocybe sp., 2♂, 2♀; emerged indoors 19 Oct. 1989 from Russula sp. [Russulaceae], 4♀, 1♂; emerged indoors 30 Oct 1989 from Suillus granulatus [Boletaceae], 2♀; emerged indoors 2 Nov 1989 from Boletus sp. (6♀, 1♂), and from Amanita sp. [Amanitaceae], 1♀; emerged indoors 1 Nov 1989 from Russula abidula [Russulaceae], 1♂ (all AMNH). Archbold Biol. Sta. S.W. Frost, 12-29-64, 1 x (AMNH). Dade Co.: Homestead, VII/31/59, W.B. Heed, 1♂ (dissected, no. 61) (AMNH); near Homestead, 30/VI/92, D. Grimaldi, 2♂ (AMNH).
Based on my dissections of males, this is a very widespread species occurring from Florida, throughout the Caribbean, Central America, northern South America, and even the Galapagos. Male genitalia throughout the range are extremely uniform. Full neotropical distribution records will be provided elsewhere. Wheeler (1954) mentioned specimens he studied from San Andres Tuxtla, Vera Cruz (field notebook no. 2264.40) and Nochistlan, Oaxaca, Mexico; Soldedad, Cienfuegos, Cuba, and El Salvador. Wheeler’s Vera Cruz records are associated with a series of 13 glass slides of at least 13 males. The specimen from Cienfuegos, Cuba (2083.2), is based on a slide mount of only the epandrium, so I cannot confirm the identity of that record, but it is likely correct given the widespread, distinctive nature of pictiventris.
COMMENTS: Wheeler (1954) provided a brief redescription based on new material, as well as a description of the egg (with four slender filaments), puparium, and internal reproductive organs. The species seems to thrive in scubby, seasonally to perennially dry habitats in the lowland neotropics, such as the Archbold Biological Station in Lake Placid, Florida, seasonal dry forest of Guanacaste Province, Costa Rica (it was an abundant species in Malaise trap samples from there), and even several of the Galápagos islands (Carson et al., 1983). The Galápagos are well known for not having any fresh water, and it has a very depauperate drosophilid fauna. Of the 16 species known from these islands, seven are introduced cosmopolitan species and perhaps only two are endemic; the rest are widespread neotropical species like H. pictiventris. Carson et al (1983) reported H. pictiventris on fungi in the mesic upland forests of Isla Santa Cruz and Isabella, but it is absent from the extremely dry, hot lowlands. Desiccation tolerance and (judging from Deyrup’s host records from Florida) an ability to breed in diverse sorts of mushrooms probably account for the widespread distribution of this species.
description: Published as part of Grimaldi, David A., 2018, Hirtodrosophila Of North America (Diptera: Drosophilidae), pp. 1 in Bulletin of the American Museum of Natural History 2018 (421) on page 1, DOI: 10.1206/0003-0090-421.1.1, http://zenodo.org/record/10687866