Brachypogon Kieffer

Brachypogon Kieffer

(Figs. 13D, 15C, 19K, 24D, 29O, 32I, 35C, 43R, 48D, 58B, 73K)

DIAGNOSIS: Only pupa of Ceratopogonidae with setae D-1-T, D-2-T, D-4-T, and D-5-T tightly appressed and on a single, short tubercle (Fig. 29O). Also only pupa with prothoracic extension abutting the antenna but not extending to the palpus (Fig. 24D) and halter extending only to the anterior margin of tergite 2 (Fig. 32I).

DESCRIPTION: Total length = 1.13–2.03 mm. Without larval exuviae retained on abdomen. Exuviae with flagellum appressed against lateral margin of face (Fig. 15C). Ecdysial tear medial to base of antenna (Figs. 15C, 79D); along prothoracic extension. Head: Dorsal apotome (Fig. 19K), without ventral line of weakness, without dorsomedial tubercle, without central dome; dorsolateral cephalic sclerite (Fig. 13D) separated from scutum by thin cuticle, separate from scutum upon emergence, each side separated medially by dorsal apotome in whole pupa; mouthparts (Fig. 24D) with mandible well-developed, lacinia absent; palpus extending posterior to posterolateral margin of labium; labium separated medially by labrum, hypopharynx; apex of antenna (Fig. 35C) anterior to posterior extent of midlength portion of midleg (portion lateral to mesosternum); sensilla: dorsal apotomals (Fig. 19K)—1 short seta present or absent, 1 campaniform sensillum; dorsolateral cephalic sclerite sensilla—1 seta, no campaniform sensillum; clypeal-labrals (Fig. 24D)—0–1 seta or 1 seta and 1 small pit; oculars (Fig. 24D)—2 setae, 2 campaniform sensilla. Thorax: Prothoracic extension (Fig. 24D) short, present only dorsolaterally abutting antenna, not extending to palpus; mesonotum with short tubercles, not extending posteromedially, not dividing metathorax medially (Fig. 48D); respiratory organ (Fig. 43R) length/width = 2.37–4.77, moderately elongate to elongate, with blunt apex, area with single subbasal spiracle slightly expanded, somewhat flattened dorsoventrally, with pores closely abutting at apex of respiratory organ, arranged in single row, with one additional subbasal pore, outer surface with annulations, without other surface modifications, with or without short, wide pedicel, base without posteromedial apodeme, membranous base of respiratory organ short, tracheal tube straight to slightly curved along length, with weak spirals restricted to base; wing (Fig. 35C) with apical tubercle lateral to apex of hind leg, separated medially by fore-, midlegs; halter apex and hind leg (Fig. 32I) just separate to just touching; halter apex abutting anterolateral knob-like extension of tergite 2; legs (Fig. 35C) with lateral margin of foreleg near midlength of wing evenly curved; hind leg visible at lateral margin of wing (Fig. 32I); with apex of foreleg well anterior to apex of midleg; apex of hind leg slightly dorsal to, partially abutting apex of midleg laterally; sensilla: anteromedials—1 seta; anterolaterals—2 setae; dorsal setae (Fig. 29O)—D-1-T, D-2-T, D-4-T, D-5-T setae, all on one tubercle, D-3-T campaniform sensillum, D-3-T posterolateral to D-4-T; supraalar 2—campaniform sensillum; metathoracics (Fig. 48D)—1 seta, 2 campaniform sensilla; M-3-T near anterior margin of metathorax. Abdomen: without pigmentation pattern, segment 2 as wide or slightly wider than segment 3, segments with undivided, thin to thick setae, with rounded to pointed, short tubercles, tergites or sternites entire, each without membranous disc; segment 9 (Fig. 73K) not strongly modified, terminal processes closely approximated basally, each projecting posterodorsolaterally to nearly laterally, tapering to pointed apex; sensilla: tergite 1 (Fig. 48D) with 8 setae, 2 campaniform sensilla, including 3 lateral sensilla, D-2-I, D-3-I closely approximated, D-7-I situated posteriorly near D-8-I; segment 4 (Fig. 58B)—D-2-IV peg-like or slender seta, D-3- IV moderately elongate seta on separate tubercles; D-5-IV short seta, D-8-IV, D-9-IV moderately elongate setae; on short, separate tubercles, posterior dorsal sensilla in transverse row, arranged medially to laterally: D-5-IV, D-4- IV, D-7-IV, D-8-IV, D-9-IV; L-1-IV elongate seta on pointed tubercle, well anterior of posterior lateral setae; L-2- IV, L-3-IV, L-4-IV moderately elongate setae on pointed tubercles, V-5-IV, V-6-IV, V-7-IV short to moderately elongate setae on rounded tubercles; segment 8 without D-3-VIII, without L-1-VIII; segment 9 (Fig. 73K)—with D-5-IX, D-6-IX campaniform sensilla.

DISTRIBUTION AND HABITAT: The genus Brachypogon is known from 200 species from every Region worldwide (Borkent 2014). Immatures are generally in such small to moderately sized lentic habitats as pools, marshes, bogs and fens as well as the mud, sand or detritus at the margins of streams and creeks. At least within the Nearctic, species are diverse and often common in bogs and fens. At least two species were common as adults in the intertidial zone in western Costa Rica (pers. obs.).

TAXONOMIC DISCUSSION: There are only seven species of Brachypogon known as pupae (Tables 2–3).

Some previous descriptions have included illustrations of the respiratory organ with pores only at the apex (Mayer 1940, Kettle & Lawson 1952, Glukhova 1979 b, Harris 1981, Elson-Harris 1990, Szadziewski et al. 1994, 1997). All specimens examined here had an additional pore near the base and in some instances this was difficult to see. If present in all Brachypogon, the arrangement of pores and the squat, rectangular to somewhat funnel-shape of the respiratory organ would be unique in the Ceratopogonidae.

Debenham (1991) illustrates three species of Brachypogon from Australia and Mayer (1940) described one species from Sweden with only two posterior lateral sensilla on segment 4 (likely L-3-IV, L-4-IV) but these should be reexamined for the smaller L-2-IV possibly present.

Thienemann (1936:176) described a pupa as "genus incertum" that is almost certainly a species of Brachypogon. It has the characteristic respiratory organ shape and arrangement of pores (one basal) and the distribution of abdominal sensilla matches fairly well (there is an extra anterior lateral sensillum that would be unique to the genus but was likely an error).

MATERIAL EXAMINED: B. nitidulus: 1 pupal exuviae, Zaklin'e, Leningrad Province, Russia, 24-VI-1972 (ZIN). B. taivoi: 1 pupal exuviae, Chu river, Kochkorka, Issyk-Kul Province, Kyrgyzstan, 30-VIII-1971 (ZIN). B. ussuriensis: 2 pupal exuviae, Ussuri Nature Reserve, Primorskii Territory, Russia, 6-VI-1973 (ZIN). B. sp.: 1 pupal exuviae (in glycerin), 6 km E Salmon Arm, BC, Canada, 6-VI-1990 (CNCI); 1 pupa, 3 pupal exuviae (in glycerin), Spanish Lake, 6 km E. Falkland, 50°29.12N 119°28.07W, BC, Canada, 27-28-V-2008 (CNCI); 1 pupal exuviae, Blue Mountain Lake, New York, USA, 3-V-1960 (NYSM); 2 pupal exuviae, Flag Glade, Pocahontas County, Virginia, USA, 24-VI-1976 (VPIC); 5 pupal exuviae, 1 km downstream lower Cascade Falls, Giles County, Virginia, USA, 3-VII-1977 (5 VPIC); 1 pupal exuviae, Moung Sayaboury, Sayaboury Province, Laos, 19-II-1967 (BPBM); 1 pupal exuviae, Houay La stream, Moung Sayaboury, Sayaboury Province, Laos, 25-XI-1967 (BPBM); 1 pupal exuviae, Moung Sayaboury, Sayaboury Muong, Laos, 19-23-II-1967 (BPBM).