Brachydeutera adusta Mathis & Ghorpade 1985

Brachydeutera adusta

Brachydeutera pleuralis of authors.—Wirth, 1964:9 [in part, revision], [Not B. pleuralis Malloch, 1928.]

Brachydeutera longipes of authors.—Bohart and Gressitt, 1951:88. [Not B. longipes Hendel, 1913.]

DIAGNOSIS.—Moderately small to medium-sized shore flies, length 2.20–3.00 mm.

Head: Frons mostly uniformly brown except for olivaceous to greenish area laterad of ocelli; 2 prominent, lateroclinate fronto-orbital bristles, if third present, usually less than ⅔ length of either posterior 2. Antenna, ventral ½ of facial carina, and clypeus brown, concolorous with frons. Aristal branches 10–12. Facial carina moderately sharp ventrally, acutely pointed ventrally, more flattened dorsally. Face, except for ventral ½ of carina and clypeus, grayish white to faintly bluish gray. Palpus pale, yellowish.

Thorax: Mesonotal chaetotaxy moderately well developed; bristles generally well developed, setae of main setal tracks larger. Mesonotum mostly brown, stripes, if at all evident, faintly inconspicuous anteriorly, light grayish to olivaceous. Scutellar ratio 0.71; distance between apical bristles subequal to that between basolateral scutellar bristle and apical bristle. Anterior notopleural bristle present, although weaker than posterior one; katepisternal bristle apparently lacking. Brownish coloration of mesonotum continued ventrally but more or less merged with grayish coloration of pleural areas. Femora mostly yellowish basally, apically becoming brownish, especially mid- and hind femur; tibiae brownish; tarsi brown, apical tarsomeres slightly darker; male hind tibia lacking patch of ventral, long setae. Wing hyaline, clear; R2+3 moderately arched; R4+5 slightly arched; costal vein ratio 3.25; M vein ratio 0.58.

Abdomen: Dorsum uniformly dark brown, ventrolateral margins of terga with some grayish coloration, vestiture sparsely microtomentose, slightly subshiny. Male terminalia (Figures 1, 2) as follows: dorsal surface of epandrium shallowly concave; epandrial width at dorsum not much wider than lateral margins of cerci; lateral margins of epandrium generally becoming narrower ventrally and with 2 sinuate emarginations, both shallow; epandrium + surstyli mostly parallel sided, apex with inverted U-shaped, deep emargination which bears setae, in lateral view with anterior surface shallowly sinuate, with slight enlargement about ½ way between apex and epandrial connection; gonite thickly developed and with posteroventral process that is curved and narrowly pointed apically.

PRIMARY TYPE MATERIAL.—The holotype male, allotype female, and paratypes (6; BBM, USNM) are labeled “MARIANA IS. Guam, Inarajan X-'57 [Oct 1957], N. Krauss.” Other paratypes are as follows: AUSTRALIA. Queensland: Cairns, 28 Apr 1957, W.W. Wirth (1; USNM). CAROLINE ISLANDS. Ponape I.: Kolonia, Aug 1956, M.R. Wheeler (1; USNM). FIJI. Suva, 7 mi [11 km] N, Nov 1967, B. McMillan (2; BMNH). MARIANA ISLANDS. Guam, SE coast: 6 May 1945, caribao hole, G.E. Bohart, J.L. Gressitt (8; BBM, CAS, USNM). SAMOA ISLANDS. American Samoa: Auasi, Tutuila, 10 Dec 1953, C. Hoyt (1; USNM). SOLOMON ISLANDS. Kolombangara: 5 Sep 1965 (1; BMNH). The holotype is double mounted (glued to a paper triangle), is in good condition (abdomen removed, dissected, and stored in an attached microvial), and is in the USNM collections of the National Museum of Natural History, Smithsonian Institution.

DISTRIBUTION (Figure 3).—Australia (Queensland), Caroline Islands (Ponape Island), Mariana Islands (Guam), Samoa Islands (American Samoa).