Ceratempis longicornis Melander

Sinclair, Bradley J., 2008, Review of three little-known monotypic empidoid genera (Diptera: Empidoidea: Brachystomatidae), assigned to Trichopezinae, Zootaxa 1754, pp. 52-62 : 56-58

Ceratempis longicornis Melander

( Figs. 4–7 )

Ceratempis longicornis Melander, 1928: 218 .

Type material examined. LECTOTYPE (here designated), male labelled: “Nasel R[iver]; W[ashington] [ USA]/ 15 July [19]22/ ALMelander”; “ TYPE / Aprerempis/ longicornis / Mel [red label]”; “ALMelander/Collection/1961” ( USNM). My lectotype label “ LECTOTYPE / of Ceratempis / longicornis Mel. / des. B.J. Sinclair 1991 [red label]” has been attached to this specimen.

Paralectotypes: Same locality as lectotype, 8.vii.1925 (1 ɗ, USNM); Ilwaco, Washington, 28.vi.1925, A.L. Melander (2 ɗ, USNM). My paralectotype labels have additionally been attached to these specimens.

Melander (1928) described this species based on males from a series of eight syntypes. However, only four syntypes have been found and the location of the remaining specimens is unknown.

Additional material examined. USA. Washington: Pacific Co., Ft Canby SP, nr Ilwaco, 16.vii.1977, sweeping coastal forest, W.J. Turner (5 ɗ, CNC, USNM, WSU); ditto, 19.vii.1978, D.D. Wilder (2 &, CAS).

Recognition. This genus and species may be distinguished from other North American empidoids by its yellow colour, bare eyes, lack of distinct acrostichals and the postpedicel with dense grey pubescence.

Description. Male. Body entirely yellowish brown except postpedicel, ocellar triangle and fifth tarsomere darker. Dichoptic, eyes bare. Gena narrow, separated from eye. Antennae inserted above middle of head; scape twice length of globular pedicel; postpedicel three-times length of head, slightly tapered, clothed in dense grey pubescence; apical arista-like or peg-like stylus lacking. Proboscis lightly pigmented; palpus directed forward, bearing stout setae; labrum half-length of labium, subequal to hypopharynx; labellum not sucker-like, bearing pseudotracheae.

Prosternum small and isolated. All setae dark. Several minute acrostichals confined to anterior fifth of notum; 5–6 dc; 2–3 pprn; 1 presut spal; 2 npl; 2 psut spal; 1 pal; 2 sctl. Several setae on antepronotum; laterotergite with patch of pale setae.

Wing (length 3.8– 4 mm) hyaline; anal lobe not produced; apical half of wing broad; stigma lacking, single basal costal seta present. Sc complete; R4 and R5 divergent; cell dm with short projection apically; cell cua (= anal cell) elongate and narrow; anal vein (CuP+CuA) reduced to fold of membrane. Calypters with fringe of brown setae. Haltere yellowish brown.

Legs slender; pulvilli broad, pad-like; empodium not pulvilliform, bearing minute setulae along ventral margin. Femora with 1–2 antero- and posteroventral preapical setae. Fore tibia lacking anteroapical comb. Mid tibia with single anteroventral row of preapical short, stout setae; mid femur with corresponding ventral row of setae at base. Apical half of hind tibia with erect, dorsal setae; posteroapical comb absent. Apex of fifth tarsomere truncate.

Abdomen with scattered setae. In dried specimens, hypopygium erect, held at right angle to horizontal ( Fig. 4 ). Terminalia ( Figs. 4, 5 ): cercus unmodified; surstyli lacking. Epandrium deeply cleft, partially encircling hypandrium; with 3 stout setae arising from tubercle; tip with dark spur. Hypandrium shallow, with pair of slender hypandrial posterior processes; postgonites medial to hypandrial processes, sinuous and pointed apically; phallus straight, tubular.

Female. Similar to male except as follows: postpedicel twice length of head; mid tibia lacking single anteroventral row of preapical short, stout setae; mid femur lacking corresponding ventral row of setae at base. Spermatheca not visible in macerated specimens. Apex of abdomen truncate, typical of Trichopezinae ( Figs. 6, 7 ): T7 with dense posterior fringe of long setae; posterior margin with large notch; S7 elongate, extending beneath S8. Segment 8 narrow; dorsal region of posterior half of T8 membranous; anterior margin with wide, short apodeme extended into segment 7; S8 narrow strip, articulated at anteroventral edge of T8. T10 narrow, undivided medially, bearing short, blunt spine-like setae. Cercus heavily sclerotized, arched dorsally, bearing short setae.

Distribution. There is only a single species of Ceratempis known, from the type locality and its surroundings in extreme southwestern Washington ( Fig. 8 , arrow); collected in coastal forests.

Remarks. Ceratempis is included in the Trichopezinae on the basis of the large anterior apodeme on female T8 and appears most closely related to Niphogenia Melander due to the shared presence of a small apical epandrial spur-like lobe and long pubescent postpedicel. A coloured habitus drawing of this species is found in Melander (1928, fig. 22). The male and female terminalia of C. longicornis is here described and illustrated for the first time. This genus can be identified using the key to genera of North American Empididae by Steyskal & Knutson (1981).

Figures

FIGURE 8. Known distribution of Boreodromia bicolor. Arrow points out also locality of Ceratempis longicornis.

FIGURES 2 – 7. Male and female terminalia. 2. Boreodromia bicolor, male, lateral view. 3. B. bicolor, female, lateral view. 4. Ceratempis longicornis, male, lateral view. 5. C. longicornis, male, hypandrium and phallus, dorsal view. 6. C. longicornis, female, dorsal view. 7. C. longicornis, female, tergum 7 removed, lateral view. Abbreviations: apod – apodeme, cerc – cercus, ej apod – ejaculatory apodeme, epand – epandrium, hypd – hypandrium, ph – phallus, ph gd – phallic guide, S – sternum, spmth – spermatheca, sur – surstylus, T – tergum. Scale bar = 0.1 mm.