Hyperlasion viridiventris ( FREY, 1945 )

Menzel, Frank, Vilkamaa, Pekka & Smith, Jane E., 2013, Overview of the Black Fungus Gnats from the Tristan da Cunha archipelago, including a redescription of Hyperlasion viridiventris (FREY) (Diptera: Sciaroidea: Sciaridae), Beiträge Zur Entomologie = Contributions to Entomology 63 (2), pp. 283-296 : 288-290

Hyperlasion viridiventris ( FREY, 1945)

( Figs 8–17 )

Literature:

– FREY (1945): 17, plate 2, figs 16–18 [as Scythropochroa (Hyperlasion) ]; – MENZEL & MOHRIG (1998): 363 [as Cratyna (Cratyna) ]; – MENZEL & MOHRIG (2000): 347, figs 215–218 [as Hyperlasion ] (not MENZEL et al. (1997): 145; misidentification, = Hyperlasion wasmanni SCHMITZ, 1918 ).

Material examined from the archipelago: NIGHTINGALE ISLAND: 2nd Pond [central of all 4 Ponds], 37°25'50"S 12°29'18"W, mire wetland, Scirpus sedges, mosses and Blechnum palmiforme ferns, Malaise trap (site 9, sample N86), 1 ♂, 26–28.iii.2005, leg. HÄNEL. West Landing, 37°24'96"S 12°28'68"W, coastal boulder platform, fur seals and tussock clumps, Malaise trap (site 5, sample N44), 4 ♂♂ 22 ♀♀, 31.iii.2005, leg. HÄNEL. West Road, 37°25'02"S 12°28'66"W, path inland from landing, tussock grassland some Scirpus sp. and alien species in path, Malaise trap (site 7, sample N46), 1♀, 28–29.iii.2005, leg. HÄNEL. TRISTAN DA CUNHA ISLAND: Between Plantation and Council Gulches, 37°07'43"S 12°29'24"W, 1267 ft. a.s.l., on path below the ‘Rim’ [escarpment], open bush ( Phylica sp. , ferns, heath and grasses), Malaise trap (site 4, sample T 45), 3 ♂♂, 10–14.ii.2005, leg. HÄNEL. Sandy Point, 37°11'47"S 12°22'61"W, 102 ft. a.s.l., woodland shrub, behind the hut, Malaise trap (site 9, sample T 47), 4 ♀♀, 21.ii.2005, leg. HÄNEL. Up Molly Gulch, on rim, below Dailies Hill, 37°11'44"S 12°33'53"W, 2270 ft. a.s.l., grassland mix, Malaise trap (site 7, sample T 49), 1 ♂, 15–21.ii.2005, leg. HÄNEL.

Other material studied:

Lectotype, ♂ [des. MENZEL in MENZEL & MOHRIG (2000): 347 and 761]. PORTUGAL: Azores, San Jorge, Lagoa do Calheta , 20.vi.1938, leg. FREY ( MZH).

Paralectotypes, 5 ♀♀. PORTUGAL: Azores, San Miguel, Furnas , forest, 23.vii–1.viii.1938 , 2♀♀, leg. FREY ( MZH); Azores, San Jorge, Ribeira do Salto , 18–23.vi.1938 , 1 ♀, leg. FREY ( MZH); Azores, San Jorge, Lagoa do Calheta , 20.vi.1938 , 2 ♀♀, leg. FREY ( MZH) .

Distribution:

The species was previously only known from the Azores (Pico, San Jorge and San Miguel Islands ). Accordingly , its status was regarded as a Macaronesian endemic ( BORGES et al. 2005). A total of 36 specimens were collected on

Tristan da Cunha and Nightingale Islands. New to Tristan da Cunha archipelago.

Description:

Male: Body length: ca 1.8 mm. Head: brown, roundish; eyebridge 2 facets wide, narrowed towards the middle into 1 facet, medially without facets. Antennae dark brown and short; 4th flagellomere 2.1–2.2 times as long as wide ( Fig. 16 ); necks short, pale and well differentiated; basal part 1.7–1.8 times as long as wide, with long, coarse setae and very long sensillae; antennal setae slightly longer than segment width. Maxillary palpi yellowish, with one club-like segment ( Fig. 12 ); palpal segment with 2–3 bristles (one long, distinctly curved outer bristle above sensory pit; 1–2 shorter bristles on apex of maxillary palp); sensory pit large, deep and on apex of maxillary palp; sensilla long. Thorax: dark brown. Anterior pronotum with 4–5 setae. Prothoracal episternum short, with 3–5 setae. Postpronotum bare. Katepisternum ( Fig. 14 ) short, low and distinctly emarginated, with cranial hollow. Mesonotum with sparse, short setae and 2–4 longer lateral bristles; scutum short, with rather short and thick laterals, thick and curved dorsocentrals in two indistinct rows, acrocentrals in anterior part only, short and curved. Scutellum distinct with 2 strong marginal bristles and some shorter setae. Legs and coxae short, strong and pale brown; coxae with strong and long setae; legs distinctly compact with short tarsi; fore femur thickened; tibiae short, shorter than tarsi, thickened towards apex; all tibiae without spines among the setae; apex of fore tibia with sparse prolateral patch of setae subapically; tibial spurs 1+2+2, shorter than diameter of corresponding tibiae, tibial spurs short and pin-like, one spur on mid and hind legs shorter (slightly unequal in length, sometimes both spurs reduced). Claws narrow and straight, without teeth. Wing ( Fig. 10 ) light brown with reduced, wedge shaped base (wing length 1.3 mm, width/length 0.45); C with sparse setosity; posterior veins weak and as the wing membrane without macrotrichia; stem of M longer than M-fork; fork of M short, triangular and very wide; x = y, both bare; CuA-stem short, about 1/3 to 1/2 x; R 1 = 0.75–0.85 R; R-R 1 short, merging with C well before base of M-fork; c = 0.65– 0.80 w. Halteres short, strong and brown with short stalk. Abdomen: slightly paler than thorax; body setae sparse, short, fine and dark. Hypopygium ( Fig. 8 ) about as high as wide, pale brown as abdomen; gonocoxites short; intercoxal area unmodified; ventral base widely rounded; inner margin with short, relatively dense setae. Gonostylus ( Fig. 9 ) longish oval, about 2.2 times as long as wide (slightly shorter than gonocoxite); apex widely rounded, with short and strong bristles (no apical tooth); innerside with 7 hyaline megasetae [spines] in upper half arranged in 2 groups (4 subapical and 3 very closely adjacent megasetae in middle). Tegmen higher than wide, unsclerotized and apically roundish; area of teeth very small and round, with fine teeth. Aedeagus very short.

Female: Similar to male but slightly larger. Body length: 2.5 mm. Head: Ocelli present. Eyebridge complete, 2 facets wide. Maxillary palpi with one segment ( Fig. 13 ), with 2–4 bristles (one distinctly longer). Antennae with 14 flagellomeres; basal segments of antennae dark; pedicel enlarged and distinctly attenuated; 4th flagellomere 1.7–2.2 times as long as wide ( Fig. 17 ); necks short and well differentiated; basal part 1.25–1.5 times as long as wide, with coarse, long, erect setae and very long sensillae; setae about as long as segment width. Thorax: Anterior pronotum with 4–5 setae. Prothoracal episternum with 7–8 setae. Katepisternum ( Fig. 15 ) larger and longer than in males, wedge shaped with cranial hollow. Legs slightly thicker than in male, forelegs strong, with swollen femur ( Fig. 11 ); tibial spurs short, one spur on mid and hind legs distinctly shorter (more strongly reduced than in males). Wings distinctly narrower than in males (wing length 1.4–1.6 mm, width/length 0.40– 0.45); R 1 shorter, = 0.5–0.8 R; c = 0.85 w; necks of halteres slightly shorter. Abdomen: long and narrow, with fine short setae, with greenish tint. All other characteristics as in males.

Discussion:

Hyperlasion viridiventris (FREY) was described from eight specimens from the Azores, of which one male (lectotype; hypopygium missing) and five females (paralectotypes) are left in the collection of MZH. The new specimens from Tristan da Cunha are in general paler than FREY (1945) indicated in the original description but this may be because the new specimens were kept in alcohol. The published record from the Canary Isle La Gomera in MENZEL et al. (1997) is a misidentification [not Cratyna viridiventris (FREY) ; = Hyperlasion wasmanni SCHMITZ ]. Consequently, to date H. viridiventris is only known from the three Azores Islands and the Tristan da Cunha archipelago. FREY (1945) wrote that there were some densely placed, short bristles inside of apex of the gonostylus. With a higher magnification however, 7 pale, hyaline megasetae can be seen in the upper half of the inner side of the gonostylus ( Fig. 9 ). Hyperlasion viridiventris is similar to the Palaearctic H. wasmanni SCHMITZ, 1918 [redescription in MENZEL & MOHRIG (2000): 346] and H. aliens MOHRIG, 2004 from Papua New Guinea and Seychelles Islands [redescription in MENZEL & SMITH (2009): 38]. Hyperlasion viridiventris and H. aliens both have relatively narrow gonostyles and a widely rounded tegmen apex. In contrast to H. viridiventris however, H. aliens has shorter flagellomeres with no sensillae on basal parts, a shorter tegmen, the inner side of the gonocoxites have sparse setae and there are only 4 hyaline megasetae on the inner side of the gonostyles. Hyperlasion wasmanni also has 7 megasetae on the inner side of the gonostyles, similar to H. viridiventris , but they are arranged differently. The species differ in that H. viridiventris has a less narrow hypopygium, the gonostyles are wider with the macrosetae more dorsally situated and the apex of gonostylus has longer setae. Furthermore, the tegmen of H. viridiventris is widely rounded, not higher than wide while the tegmen of H. wasmanni has a lateral constriction and flattened apex. H. viridiventris has a very distinct and unique extremely swollen (almost triangular) basal segment of the maxillary palp, and in the males the long outer bristles are typically above the sensory pit. With both of these characteristics it is possible to distinguish H. viridiventris (FREY) from H. wasmanni SCHMITZ and H. aliens MOHRIG.

Figures

Figs 8–17: Hyperlasion viridiventris (FREY), male and female:– Fig. 8: Hypopygium in ventral view,male; –Fig. 9: Right gonostyle in ventral view, male; – Fig. 10: Wing in lateral view, male; – Fig. 11: Fore leg in lateral view, female; – Fig. 12: Maxillary palp in lateral view, male; – Fig. 13: Maxillary palp in lateral view, female; – Fig. 14: Katepisternum in lateral view, male; – Fig. 15: Katepisternum in lateral view, female; – Fig. 16: 4th flagellomere in lateral view, male; – Fig. 17: 4th flagellomere in lateral view, female.