Allotrichoma adustum Mathis 1991

Allotrichoma (Pseudohecamede) adustum Mathis

Allotrichoma (Pseudohecamede) adustum Mathis, 1991:17–19 [key, figures].

SPECIMENS EXAMINED.—BELIZE. Stann Creek District: Coco Plum Cay, Jul 1989, W.N. Mathis (1); Tobacco Range, Jul 1989, W.N. Mathis (1, 2); Twin Cays (Aanderaa Flats, south end of East Island), Nov 1987, Mar 1988, Jul 1989, D. Mathis, W.N. Mathis (4, 3).

DISTRIBUTION.—Nearctic: USA (FL). Neotropical: Bahamas, Belize, Ecuador, West Indies (Grand Cayman, Jamaica).

NATURAL HISTORY.—All Belizean specimens of this species that I have collected occurred sympatrically with A. abdominale. Although they are readily distinguished from the latter on the basis of morphological characters, how they partition the habitat is unknown. Most specimens were taken from the mud flat at Aanderaa Flats.

DIAGNOSIS.—Externally this species is very similar to A. fasciale Hendel in lacking a gray- to silver-colored stripe through the postpronotum and notopleuron and in the thoracic coloration, which is generally chestnut brown. It differs from A. fasciale in having the abdominal tergites mostly silvery gray; at most with basal two terga slightly brownish gray.

Allotrichoma (Pseudohecamede) adustum

Pseudohecamede facialis, in part, of author’s (misidentification): Wirth, 1965:737 [nearctic catalog]; 1968:5 [neotropical catalog].

DESCRIPTION.—Small to moderately small shore flies, length 1.65 to 2.20 mm.

Head: Proclinate fronto-orbital seta present, subequal in length to reclinate seta; pseudopostocellar setae present, about ¾ length of ocellar setae. Arista with basal thickened portion about ⅓ total aristal length; arista bearing 4–6 dorsal rays, basal 3 subequal in length. Face of female bicolored, silvery colored on ventral ⅔, concolorous with gena, brown dorsally, concolorous with frons; face of male more unicolorous, brown, concolorous with frons; lower facial margin shallowly emarginate.

Thorax: Presutural seta either absent or inconspicuous, similar to surrounding setulae; acrostichal setulae in 4 rows although lateral rows with sparse to lacking setulae anteriorly; mesonotum, anepisternum, and anepimeron brown to dark brown, pleural areas only slightly lighter in coloration ventrally and lacking horizontal stripes; katepisternum silvery colored. Wing milky white; veins pale colored, costal vein yellowish, those behind whitish; costal vein ratio 0.45; M vein ratio 0.44. Legs, except for tarsi, grayish to grayish brown; tarsi with basal 3 tarsomeres yellowish, apical 2 grayish brown.

Abdomen: Terga mostly silvery gray, some specimens with basal 2 terga very lightly brownish. Male terminalia (Figure 16) as follows: Epandrium in lateral view a narrow band, ventral margin not produced anteroventrally; cercus moderately narrow in lateral view, although obviously wider than width of epandrium; surstylus comparatively well developed, length longer than width of epandrium, apex slightly but irregularly angulate; aedeagal apodeme with basal portion small, irregularly shaped, with a moderately long posterior projection, which attaches to the hypandrium, and a longer, slightly tapered, dorsal projection, which attaches to the base of the aedeagus; aedeagus simple, distinctly tapered toward apex, apex narrowly rounded; gonite as an irregular rectangle, posteroventral angle only slightly produced, anterodorsal surface sinuate; hypandrium in lateral view nearly flat, with no evident development of separate arms.

TYPE MATERIAL.—The male holotype is labeled “BELIZE. Stann Crk. Dist. Twin Cays (Aanderaa Flats) 17–21 March 1988 Wayne N. Mathis.” The allotype female and one other female bear the same label data as the holotype. The holotype is double mounted (minute nadel in plastic elastomere block), is in excellent condition, and is deposited in the Smithsonian Institution (USNM). Other paratypes are as follows: BAHAMAS. Exuma Cays: Warderick Wells Cay, 10 Jan 1953, L. Giovannoli (1; USNM). Fortune Island (or Long Cay), near Albert Town, 7 Mar 1953, E.B. Hayden, L. Giovannoli (1; USNM).

BELIZE. Stann Creek District: Coco Plum Cay, 31 Jul 1989, W.N. Mathis (1; USNM); Tobacco Range, 30 Jul 1989, W.N. Mathis (1, 2; USNM); Twin Cays, Aanderaa Rats, 23–25 Jul 1989, 7–19 Nov 1987, D. Mathis, W.N. Mathis (3; USNM); Twin Cays, south end of East Island, 25 Jul 1989, W.N. Mathis (1; USNM).

ECUADOR. Guayas Gala (night), Dec 1955, J.R. Levi-Castillo (1, 1; USNM). Los Rio Vinces, Oct 1954, J.R. Levi-Castillo (1; USNM).

UNITED STATES. Florida: Dade Co., Everglades National Park, 10 Mar 1955, H.A. Denmark (1; USNM). Big Pine Key, 30 Dec 1954, H.V. Weems (1; USNM). Monroe Co., Bahia Honda Key (seashore), 11 Apr 1970, W.W. Wirth (1; USNM).

WEST INDIES. JAMAICA. Milk River Bath (mangrove), 11 Mar 1970, T. Farr, W.W. Wirth (2; USNM). Negril Beach (rocky shore), 12 Mar 1970, W.W. Wirth (1; USNM).

DISTRIBUTION (Figure 17).—Western Hemisphere from 30° north latitude to 3° south latitude, primarily in countries around or within the Caribbean and Gulf of Mexico but also Ecuador.

ETYMOLOGY.—The species epithet, adustum, is a Latin adjective for the color brown, in allusion to the brown, mostly concolorous anepisternum and anepimeron.