Dryxo freidbergi Mathis & Zatwarnicki 2002

Dryxo freidbergi

DIAGNOSIS.—This species is distinguished from congeners by the following combination of characters: parafacial with wide, blackish brown stripe immediately laterad of antennal base contrasting distinctly with silvery gray remainder of parafacial; mesonotum with numerous small, dark brown spots at bases of setae and setulae, 2 large, somewhat triangular, dark brown spots at posterior margin of scutum, and 2 spots on scutellum around bases of apical scutellar setae; postsutural supra-alar seta greatly reduced or absent; anepisternum lacking moderately long, slender setae along posterior margin; katepisternal seta usually greatly reduced, much weaker than notopleural seta, or lacking; femora except apices gray, concolorous with pleural areas, contrasting with yellow tibiae; male hindtarsi lacking long, slender setae on dorsal surface; tergites with dark band toward anterior margin, at most with a very thin, dark area along posterior margin; and 1st tergite with sparse, inconspicuous, dorsally erect setulae.

DESCRIPTION.—Large to very large shore flies, body length 5.90–6.45 mm; generally white with some brown coloration dorsally and with apices of legs yellowish.

Head: Generally densely microtomentose. Frons mostly silvery white to silver with some golden areas medially, anterior of anterior ocellus; length of inner and outer vertical setae about coequal, both reduced and about equal to length of pedicel; ocelli arranged either in equilateral or slightly isosceles triangle, usually with distance between posterior ocelli shorter than between either posterior ocellus and anterior ocellus. Antenna blackish brown to black; scape and pedicel sometimes with considerable fine, grayish to brownish microtomentum, especially dorsally; arista silvery white, bearing 8 or 9 dorsal rays. Face white to faintly tannish white, bare except for series of setulae paralleling frontal suture; parafacial concolorous with face except for a wide, brown to blackish brown stripe immediately laterad of antennal base. Eye slightly higher than wide. Gena high, anterior portion concolorous with face and parafacial, becoming whiter posteriorly; gena-to-eye ratio 0.50–0.54. Clypeus mostly bare medially, shiny black, becoming densely microtomentose laterally, especially along ventral margin.

Thorax: Mesonotum with small dark brown spots at bases of setae and setulae, 2 large, somewhat triangular to quadrate dark brown spots toward posterior margin of scutum, varying amounts of dark brown areas medially and along setal tracks (none consistently expressed), and 2 spots on scutellum at bases of apical scutellar setae; postsutural supra-alar seta greatly reduced or absent; anepisternum either lacking moderately long, slender setae along posterior margin or bearing 1 small, slender seta; katepisternal seta usually greatly reduced, much weaker than notopleural seta, or lacking. Wing hyaline; R stem vein bearing 4–6 short, thin setulae dorsally; costal-vein ratio 0.44–0.50; M-vein ratio 0.72–0.84. Femora except apices microtomentose, whitish gray, concolorous with pleural areas, contrasting with yellow to yellowish orange tibiae with faint and thin white microtomentum; male foretarsi similar to female, unmodified; forebasitarsomere of male similar to basitarsomeres of mid- and hindlegs; some lateroapical setae of forebasitarsomere of male parallel sided and bluntly rounded apically; hindtarsi lacking long, slender setae on dorsal surface.

Abdomen: Generally whitish gray and lacking bands, but with some brown to golden brown along extreme posterior margin; sometimes tergites 2 and/or 3 with some dark brown irregular maculations anterolaterally; 1st tergite with sparse, inconspicuous, dorsally erect setulae. Male terminalia (Figures 30–32): epandrium yellowish to yellowish orange, frequently exposed and conspicuous from dorsal angle, in posterior view (Figure 30) rounded arch-shaped, narrow dorsally, arms wider at dorsolateral level, ventrally becoming narrower; cercus ovoid, wider subventrally; presurstylus in posterior view (Figure 30) broadly triangular, length only slightly more than basal width, dorsomedial angle very narrowly produced, medial margin irregularly concave, ventral apex broadly rounded, lateral margin very shallowly arched; postsurstylus in lateral view (Figure 32) wide basally, becoming narrower to apex, with subapical, angulate indentation, in ventral view with both lobes of bilobed apex of about equal size, inner lobe essentially bare of setulae; aedeagus in lateral view (Figure 32) with base very wide, immediately narrowed, especially on inner surface, external surface with recurved, narrow lobe at midlength, apex irregularly and relatively broadly rounded; aedeagal apodeme in lateral view (Figure 32) with keel very shallow, ridge-like, bifurcate arms at attachment with hypandrium long; hypandrium moderately wide and deep.

TYPE MATERIAL.—The holotype male is labeled “CAMEROON Kribi (beach) Rt. N7 28, 29.XI.1987 [28–29 Nov 1987] A. FREIDBERG/HOLOTYPE Dryxo freidbergi W.N. Mathis & Zatwarnicki USNM [red label; species name, gender symbol, and “& Zatwarnicki” handwritten].” The holotype is pinned directly, is in excellent condition, and is deposited in the NMNH. The allotype female and six other paratypes (3, 2; USNM) bear the same locality data as the holotype.

DISTRIBUTION.—Afrotropical: Cameroon.

ETYMOLOGY.—The specific epithet, freidbergi, is a genitive patronym to honor one of the collectors of this new species from Africa.