Hecamede nuda Wirth 1956

Hecamede (Soikia) nuda Wirth

Hecamede nuda Wirth, 1956:379–380.—Cogan, 1980:657 [Afrotropical catalog].

Soikia argentata Canzoneri and Meneghini, 1969:1484.—Cogan, 1980:657 [synonymy with H. nuda].

Soikia nuda.—Canzoneri, 1981:203–204 [generic combination, list, Senegal]; 1982:58 [list, Sierra Leone].

DESCRIPTION.—Small to medium-sized shore flies, length 1.90 to 3.5 mm.

Head (Figures 48–50): Fronto-orbits and ocellar triangle densely microtomentose, microtomentum white to whitish gray; mesofrons yellowish orange on anterior portion; setae of frons poorly developed, frequently only 1 fronto-orbital seta that is oriented posterolaterally, if a 2nd is present, proclinate and inserted anteriad of reclinate seta; ocellar setae weakly developed, inserted slightly anteriad of anterior ocellus; both inner and outer vertical setae present, although inner seta much reduced, length about half that of outer seta. Antenna entirely pale, yellowish orange; arista mostly white to lightly mostly yellow, usually bearing 5 dorsal branches, occasionally with fewer. Face entirely microtomentose, microtomentum mostly white with pearly luster and some faint orangish coloration; conical facial prominence rounded in lateral view; facial setae 2, black, arising from bare, basal spots. Gena essentially concolorous with face, lacking black setae; gena high, eye-to-cheek ratio averaging 0.80. Clypeus bare, shiny black.

Thorax: Mesonotum densely microtomentose, gray to tan, except for portion immediately dorsad of cervix, which is shiny, black, dorsomedial margin as 2 short, extended areas; pleural areas gray to whitish gray; setae generally sparse and weakly developed, especially evident on disc of scutellum, with 20 or fewer setulae, and anepistermum, both of which have few setulae; acrostichal setulae in 3 or 4 regular rows; lacking a presutural, prescutellar acrostichal, or katepisternal seta and setae that are present frequently pale colored. Posterior surface of fore coxa and adjacent area of katepisternum black, shiny, bare, black area not extended dorsad above level of fore coxa. Legs with femora mostly gray, densely microtomentose; tibiae generally mostly yellow, but fore tibia usually with a ring of dark brown coloration, sometimes dark coloration more extensive; middle tibia with mostly white microtomentum on anterior surface; tarsi mostly yellow except for apical 1–2; fore femur with a conspicuous row of 10 to 12 stout setae along posteroventral margin; fore basitarsus with 2 or 3 black setae inserted toward base on posteroventral surface; hind basitarsus with 2 or 3 long, black setae inserted at base on anteroventral surface. Wing costal vein ratio averaging 0.40; M vein ratio averaging 0.60; last section of vein M straight.

Abdomen: Male terminalia (Figures 51, 52) as follows: 5th tergum more or less evenly sclerotized; epandrium (Figure 51) a more or less parallel-sided, dorsal band; surstylus (Figure 51) in lateral view long and narrow, curved anteriorly, tapered very gradually to acutely pointed apex, anterior margin with a few tiny setulae; cercus (Figure 51) moderately long and narrow, length less than height of epandrium in lateral view; gonite (Figure 52) irregularly and roughly triangular in shape in lateral view, with a narrow connection or gonal arch above aedeagus, lacking a larger, subapical seta; aedeagal apodeme (Figure 52) narrowly triangular in shape in lateral view; aedeagus (Figure 52) long and distinctly tapered toward apex; hypandrium shallowly concave and with a median structure anteriad, at juncture with sternum.

TYPE MATERIAL.—The holotype male of Hecamede nuda is labeled “beach at Umkomaas[,] Natal[,] S. Afr. 9 Dec. 1954[,] B.Stuckenberg/HOLOTYPE Hecamede nuda W.W.Wirth [red, species name and gender handwritten]/Hecamede nuda Wirth det. WWirth [species name and author handwritten]/Type No 62814 USNM [red, number handwritten].” The holotype is double mounted (thin wire that is twisted around the main pin), is in excellent condition, and is deposited in the USNM (62814).

The holotype male of Soikia argentata is labeled “plage SOMONE SENEGAL 4. X. 1961 [handwritten]/dans detritus vegetaux [handwritten]/HOLOTYPUS Soikia gen. n. argentata sp. n. [red, handwritten except for “HOLOTYPUS”].” The holotype is double mounted (pin in a rectangular card), is in good condition (the abdomen has been removed and dissected, and the parts are in a microvial that is attached to the pin), and is deposited in the MNHN.

OTHER SPECIMENS EXAMINED.—Afrotropical: KENYA. Gazi (60 km S Mombasa, Rt. A14), 5 May 1991, A. Freidberg, F. Kaplan (2; USNM). Mombasa, 1–3 Jan 1971, A.E. Stubbs (5, 4; BMNH); Ngomeni (150 km N Mombasa), 4 Dec 1989, A. Freidberg, F. Kaplan (3, 2; TAU, USNM).

MADAGASCAR. Antseranana: Sambava (beach), 14 Apr 1991, A. Freidberg, F. Kaplan (2; USNM). Toamasina: Fénérive (beach), Dec 1955, B. Stuckenberg (2; USNM). Toliara: Fort Dauphin (beach), 18 Apr 1991, A. Freidberg, F. Kaplan (27, 16; TAU, USNM); Morondava, 28–31 Mar 1990, W.E. Steiner, C. Kremen, V. Razafimahatratra (1; USNM).

MOZAMBIQUE. Lourenço Marques, 1 Jan 1956, B. Stuckenberg (1, 1; USNM).

OMAN. near Al Ashkara (21°64′N, 59°30′E, 5 m, coastal dunes, to light), 10 Oct 1990, M.D. Gallaghar (1; NMWL); Dhofar, Mughsail beach (in burrow of turret-building crab, Ocypode rotundata Miers), 11 Oct 1990, M.J. Ebejer, J.C.Deeming (1; NMWL).

SOUTH AFRICA. Natal: Umkomaas, 11 Oct 1983, A. Freidberg (1; USNM); Umkomaas (beach), 9 Dec 1954, B. Stuckenberg (4, 1; ANSP, NMP, USNM).

DISTRIBUTION (Figure 53).—Old World. Afrotropical: Kenya, Madagascar, Mozambique, South Africa. Palearctic: Oman. Canzoneri (1981, 1982) reported this species from Senegal and Sierra Leone respectively, but I have not studied species from either country in West Africa.

NATURAL HISTORY.—Wirth (1956:380) reported that Stuckenberg, the collector of the type series, found adults of this species resting on the sides of crab burrows (crabs of the genus Ocypode Fabricius) within a few inches of the entrance. The burrows are very common in the intertidal zone on the beaches of Natal. The female from Oman was also collected from the burrow of a turret-building crab, specifically Ocypode rotundata Miers. This habitat is also where some Omanian specimens of H. maritima (see p. 27) were collected and is not unique to this species or subgenus.

DIAGNOSIS.—This species and its sister species, H. tomentosa, are very distinctive and are not likely to be confused with any others. The two sister species, although similar, can be distinguished by the characters outlined in the key. In addition, the male terminalia of this species are diagnostic, especially the long, slender and curved surstylus, the gonite, which is pointed ventrally and lacks lobes, and the shorter and more robust aedeagus (Figures 51, 52).

NOTES ON VARIATION.—The population from Oman is quite distinct externally, and I have chosen to recognize its distinctiveness by describing here the external features that characterize it.

Head: Mesofrons yellowish orange on anterior portion; frons laterad and anteriad of ocelli with 2 bare bands that extend anteriorly from ocelli; coloration immediately laterad and anteriad of ocelli black; setae of frons poorly developed, frequently only 1 weak, fronto-orbital seta that is oriented posterolaterally, if a 2nd is present, proclinate and inserted anteriad of reclinate seta; ocellar setae weakly developed, inserted slightly anteriad of anterior ocellus. Gena high, eye-to-cheek ratio averaging 0.65.

Thorax: Mesonotum densely microtomentose, gray to tan, except for area immediately dorsad of cervix, which is shiny, black, dorsomedial margin evenly rounded; pleural areas gray to whitish gray; setae generally sparse and weakly developed, especially evident on disc of scutellum, with 15 or fewer setulae, and anepisternum, both of which have few setulae. Area comprising lateral and posterior surfaces of fore coxa and adjacent area of katepisternum black, shiny, black area extended dorsad to include anterior spiracle. Legs with femora mostly gray, densely microtomentose; fore tibia mostly blackish, only apices mostly yellow; hind basitarsus with 2 to 4 black setae inserted near base on anteroventral surface. Wing costal vein ratio averaging 0.36; M vein ratio averaging 0.60; last section of vein M straight.

Abdomen: As in nominate description.

Available samples suggest that the Omanian population is allopatric with those from the subsaharan Africa (Kenya to South Africa). I suspect, however, that additional collecting will reveal more or less continuous populations of this species along most if not all of the east coast of Africa and onto the Arabian peninsula. Moreover, I would be surprised not to find that the variation evident in the Omanian population is clinal.