Brachypogon singularis (Santos Abreu)

Dominiak, Patrycja, Szadziewski, Ryszard & Salmela, Jukka, 2020, Descriptions of Brachypogon surma sp. n. from Finland and B. singularis (Santos Abreu, 1918) from the Canary Islands (Diptera, Ceratopogonidae), Norwegian Journal of Entomology 67, pp. 235-245 : 238-244

Brachypogon singularis (Santos Abreu)

( Figures 4–7 )

Ceratolophus singularis Santos Abreu, 1918: 317 (female, Canary Islands), Borkent & Dominiak 2020: 156 (nomen dubium).

Brachypogon singularis : Borkent 1997: 5 (combination, nomen dubium).

Ceratolophus rufigastris Santos Abreu, 1918: 321 (female, Canary Islands); Borkent & Dominiak 2020: 156 (nomen dubium). Syn. n.

Norwegian Journal of Entomology 67, 235–245 (2020)

Brachypogon rufigastris : Borkent 1997: 5 (combination, nomen dubium).

Ceratolophus obscurus Santos Abreu, 1918: 323 (as variety of rufigastris , female, Canary Islands); Borkent & Dominiak 2020: 156 (nomen dubium). Syn. n.

Brachypogon obscurus : Borkent 1997: 5 (combination, nomen dubium).

Material examined. Neotype. Adult male,

present designation, Spain, labelled as follows:

B. (I.) singularis, ESP. Gran Canaria, Bco.

Tirajana, 16 XI 1995, light trap, Baez, Nilsson & Malmqvist, ( CEIG). Other materials . Same data as the neotype, 8 males, 2 females, ( CEIG) .

Diagnosis. Males of the species can be easily distinguished by having triangular aedeagus with subapical ring bearing strong ventral spine and two long dorsal plate-like projections, and U-like, strong and pointed parameres. Female similar to other species, with 2 unequal seminal capsules

Dominiak et al.: Descriptions of Brachypogon surma and B. singularis

and two internal, rod-like sclerotizations under the abdominal sternite 9.

Description. Male. Colouration. Body dark. Tarsomeres 1–2, especially those of mid leg, slightly paler; hind basitarsus dark. Head. Antenna ( Figure 4a ) with flagellomeres 2–5 or 2–10 fused (n=9); total flagellum length 0.65–0.70 mm (n=6), AR 0.95–1.00 (n=5). Palpus ( Figure 4b ) with third palpal segment stout, with well-defined shallow sensory pit located on distal half; length 0.044–

Norwegian Journal of Entomology 67, 235–245 (2020)

0.052 mm, PR III 1.7–2.1 (n=7); fourth palpal segment with 2–3 setae. Thorax. Anepisternum bare, katepisternum with single seta; scutellum with 4 marginal setae. Legs slender; hind leg with tibial comb composed of 7–9 large spines (n=9), and basitarsus with single row of palisade setae ( Figure 4c ); tarsomere 5 of all legs with small, equal-sized claws, lacking inner teeth, each with single long basal seta at base and with bifid apex; hind tarsal ratio TR

III

1.5–1.7 (n=8). Wing membrane slightly infuscated ( Figure 4d ), with some macrotrichia along apical margin; two short radial cells present, similar in length, first one slit-like, second broader; wing veins infuscated; wing length 1.10–1.20 mm, CR 0.53–0.54 (n=5). Genitalia ( Figures 7a–h ). Apicolateral processes of tergite 9 weakly developed ( Figures 7a, b, d, e ), each bearing single seta. Cerci small, each with single strong seta ( Figures 7a–c ). Proctiger heavily sclerotized, rectangular, frame-like ( Figures 7a, b ). Posterior margin of sternite 9 gently rounded ( Figure 7a ). Gonocoxite stout, 1.7 times longer than broad ( Figure 7a ). Gonostylus nearly as long as gonocoxite, straight, with slightly pointed apex ( Figure 7a ). Aedeagus triangular with high basal arch ( Figures 7f, g ); subapical ring armed with strong ventral spine curved ventrally and two dorsal long plate-like projections. Parameres ( Figure 7h ) with dorsobasal half relatively long, with well-established horn-like lateral processes; ventroapical half with basal part fused and apical part bifid, composed of two horn-like apicolateral processes.

Female. Colouration. Body dark. Tarsomeres 1–2, especially those of mid leg, slightly paler; hind basitarsus dark. Abdomen slightly paler (in both specimens examined filled with eggs). Head. Antenna with 8 proximal flagellomeres ovoid to subcylindrical, and 5 distal flagellomeres cylindrical; length of flagellum 0.43–0.44 mm, AR 1.22–1.23 (n=2). Maxillary palp ( Figure 5a ) with third palpal segment stout, with large but shallow sensory pit located apically; length 0.046 –0.049 mm, PR III 1.6–1.9 (n=2); fourth palpal segment bearing 2–3 setae. Mandible with 12 teeth, smaller in basal half, bigger towards apex ( Figure 5a ). Thorax. Anepisternum bare, katepisternum bearing single seta; scutellum with 4 setae. Femora and tibiae of all legs slender; hind tibial comb composed of 8–9 spines ( Figure 5b ); hind basitarsus armed with single row of palisade setae; all legs with tarsomere 4 subcylindrical and tarsomere 5 armed with slightly unequal large claws ( Figure 5b ), each with basal inner tooth; hind tarsal ratio TR III 1.9–2.0 (n=2). Wing membrane with single row of macrotrichia along whole distal and posterior margin ( Figure 5c ); two short and narrow radial cells present; wing veins infuscated; wing length 1.16 mm, CR 0.61 (n=1). Genitalia ( Figures 6a , 7i ). Sternite 8 divided lengthwise, separated from tergite 8, desclerotized medially, with broad triangular excavation on posterior margin. Medioventral halves of sternite 9 with slender, pointed arm; two internal, rod-like sclerotizations under sternite 9 present ( Figures 6a , 7i ). Sternite 10 with one pair of setae. Two ovoid, unequal, highly sclerotized seminal capsules present ( Figure 6b ), dimension (mean values) 0.054x 0.033 mm and 0.075x 0.054 mm (n=2).

Immature stages. Unknown.

Comments. The remains of the Santos Abreu’s collection of biting midges from the Canaries were examined by Borkent (1997), who designated the lectotypes, proposed several new junior synonyms, and treated some other names as nomina dubia. Among the latter, there are three names originally placed in the genus Ceratolophus Kieffer, 1899 but belonging to the subgenus Isohelea of Brachypogon , i.e. singularis (p. 317), rufigastris (p. 321) and obscurus (p. 323, as variety of rufigastris ). The type materials of these are believed to be destroyed ( Borkent 1997). In the new world catalogue of biting midges ( Borkent & Dominiak 2020) all these names were still treated as nomina dubia. In order to clarify the taxonomic status of these names and to stabilize the nomenclature within the taxonomically complicated subgenus Isohelea , we selected a male specimen of Brachypogon collected in the Canary Islands and designated here a neotype for Ceratolophus singularis Santos Abreu, 1918 . Among the materials examined there were specimens of both sexes, and the females perfectly fit to the description of this species given by Santos Abreu. Regarding the two remaining names, we propose here to treat them as conspecific, and moreover – as synonymous with B. singularis (new synonyms). Except of rather unimportant differences in colouration of the body, there are no other characters which allow to distinguish B. rufigastris and B. obscurus . According to the original description ( Santos Abreu 1918) female of B. rufigastris is characterized in having hind basitarsus as long as the combined length of two next tarsomeres (three tarsomeres in B. singularis ) and equal claws lacking inner teeth (slightly unequal with inner teeth in B. singularis ). However, when the results of Borkent’s (1997) study are taken into the consideration, it appears obvious, that the specific traits indicated by Santos Abreu as crucial for species delimitation are of much less taxonomic value. Borkent (loc. cit.) proved that many names authored by Santos Abreu are synonymous. It is essential to mention that biting midges of the genus Brachypogon are minute and especially females look very much alike, and thus their correct identification based on pinned specimens seems to be quite impossible or at least may cause difficulties.

Brachypogon singularis and B. clavatus ( Clastrier, 1966) are two species of the subgenus Isohelea currently known from the Canaries.

Rudimentary internal sclerites under the abdominal sternite 9 in females of B. singularis are homologous to those present in females of the subgenus Wirthomyia Vargas, 1973 of Culicoides Latreille, 1809 .

Figures

FIGURE 4. Brachypogon singularis (Santos Abreu, 1918), male (a, d – neotype). a. Antenna,b. Maxillary palp, c. Tibial comb and basitarsus of hind leg, d. Wing.

FIGURE 5. Brachypogon singularis (Santos Abreu, 1918), female. a. Mouthparts, b. Hind legs, c. Wing.

FIGURE 6. Brachypogon singularis (Santos Abreu, 1918), female.a. Abdominal sternites 8 and 9, ventral view, b. Seminal capsules.

FIGURE 7. Brachypogon singularis (Santos Abreu, 1918), genitalia of male (a–h) (a, f, h – neotype), and female (i). a. Male genitalia, ventral view, b–e. Ventral view of cerci and tergite 9, f. Aedeagus, ventral view, g. Aedeagus, lateral view, h. Parameres, i. Female abdominal sternite 9. Scale bar 0.1 mm.