Hebecnema anthracinella, Michelsen, 2019

Michelsen, Verner, 2019, Macaronesian Muscidae (Diptera). I. The genus Hebecnema Schnabl with description of a new Canarian endemic species and a review of the European fauna, Zootaxa 4706 (2), pp. 332-348 : 335-336

Hebecnema anthracinella sp. nov.

( Figs 2 A‒D, 8C)

“ Hebecnema vespertina (Fallén) ”; Becker 1908 a: 96 (Tenerife); Frey 1935: 134 (Gran Canaria, Tenerife); Santos Abréu 1976: 71 (Tenerife, La Palma); Chandler 1979 (La Palma). Misidentifications.

“ Hebecnema affinis Malloch ”; Hennig 1956: 138 (Canary Islands only); Báez 1977: 15, figs 2‒4 (Gran Canaria, Tenerife, La Gomera, La Palma). Misidentifications.

Becker (1908 a) recorded Hebecnema vespertina (Fallén) from the Canary Islands based on a series of males and females from Tenerife identified by P. Stein. However, it is evident from the treatment of the European Muscidae by Stein (1916) that his concept of H. vespertina included two species of Hebecnema that both have bare eyes but differ by the yellow vs. black colour of the halteres. This was first pointed out by Malloch (1921), who reserved the name H. vespertina for the species with black halteres and described the one with yellow halteres as a new species, H. affinis Malloch. Unfortunately , it was subsequently objected that J.R. Malloch should have used the name H. vespertina for the species with yellow halteres. The muddled nomenclature of the two species was ultimately settled by Pont (1984), who designated a lectotype linking the name H. vespertina (Fallén) to the species with yellow halteres, and he further decided that the European species with black halteres should be known as H. nigra (Robineau-Desvoidy) .

Frey (1936) recorded Hebecnema vespertina from the Canary Islands (Gran Canaria, Tenerife) based on new material identified by the muscid specialist L. Tiensuu. From the treatment of the Finnish Muscidae by Tiensuu (1935) it is evident that his concept of H. vespertina follows Malloch (1921) and accordingly refers to a species with black halteres.

Hennig (1956), who also followed the nomenclature of Malloch (1921), saw some of the specimens from Tenerife recorded in Becker (1908 a) and found them identical with H. affinis Malloch , the species with yellow halteres.At the same time he listed the record by Frey (1936) under H. vespertina sensu Malloch , the species with black halteres, without further comments. A posthumous publication by Hennig (1978) makes it clear that he did not accept the record of H. vespertina sensu Malloch from the Canary Islands.

New material of Hebecnema attained during fieldwork on my several visits to the western Canary Islands of Gran Canaria, Tenerife and La Gomera contained two species only, viz. H. fumosa (Meigen) with pilose eyes and yellow halteres and a species with bare eyes and blackish clouded halteres and calypteres. The colour characteristics of the second species agree with the Madeiran H. anthracina , but examination of the male terminalia showed that the western Canarian taxon represents a new species.

Finally, my re-examination of the Canarian specimens of Hebecnema identified by W. Hennig and L. Tiensuu as H. affinis and H. vespertina respectively revealed that they belong to the same species and are misidentifications of the endemic Canarian H. anthracinella sp. nov.

Material examined. CANARY ISLANDS: Type material [ NHMD]: Holotype ♂, LA PALMA: Las Tri- cias, 28°47´N 17°58´W, 660m, 11‒16.i.2013 (V. Michelsen) . Paratypes: GRAN CANARIA: Sagrado Corazón, 28°02´N 15°33´W, 700‒825m, 3♂, 1♀ 12‒17.i.2017 (V. Michelsen) ; TENERIFE: Los Portelas, 28°19´N 16°50´W, 830‒860m, 2♂, 1♀ 16.i.2012 (V. Michelsen) ; LA GOMERA: Los Loros, 28°09´N 17°16´W, 520‒770m, 1♂, 2♀ 5‒7.ii.2008, 1♂, 2♀ 18‒23.i.2012 (V. Michelsen) . Other material [ MNB, MZH, NHMD]: GRAN CANARIA: San Isidro, 28°01´N 15°33´W, 910‒975m, 2♂ 13‒18.i.2014 (V. Michelsen) ; TENERIFE: 1♂ xii.1900 (T. Becker) ; Oro- tava, 2♀ i.1901 (T. Becker) ; Guimar, 1♀ vi.1904 (T. Becker) ; Valle de S. Andrés, 1♀ 2.iii.1950 (H. Lindberg) ; Sta Ursula, La Quinta, 1♂ 9.iv.1993 (M. Koponen) ; Carrizal Alto, 28°19´N 16°51´W, 640‒730m, 1♂ 30.i‒3.ii.2016 (V. Michelsen) . LA GOMERA: El Cedro, c. 1000m, 1♀ 23.iii.1950 (H. Lindberg) ; 4♀ 21.xi.2002 (V. Michelsen) ; Agu- lo, Lepe, 2♂ 12.i.2006 (V. Michelsen) ; Epina, 28°10´N 17°18´W, 600‒670m, 1♂, 1♀ 13‒16.i.2019 (V. Michelsen) ; Arguamul, 28°11´N 17°17´W, 600‒750m, 1♀ 14.i.2019 (V. Michelsen) ; Meriga, 28°09´N 17°14´W, 600‒750m, 1♂, 1♀ 16.i.2019 (V. Michelsen) ; Lomito Fragoso, 28°07´N 17°10´W, 220‒250m, 1♀ 19‒24.i.2019 (V. Michelsen)

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Etymology. The specific name anthracinella should signal a possible closest relationship with the Madeiran Hebecnema anthracina .

Diagnosis. Parafacials dull brownish grey in anterodorsal view. Thorax and abdomen with dark shine through thin brownish pruinosity; male abdomen with a narrow median dark stripe on tergites III‒V; female abdomen with uniform dark shine. Wing, calypteres and halter blackish clouded. Legs black with mid and hind tibiae darkly ochre yellow. Eye practically bare. Male head in profile with middle part of parafacial concealed behind the eye. Distance between presutural rows of acrostichal setae equal to (male) or slightly exceeding (female) their distance to rows of dorsocentral setae; setulae between acrostichal rows in two irregular rows. Vein C bare on dorsal surface. Hind tibia with 1‒2 av setae. Male sternite V, surstylus and cercus distinctive ( Figs 2 A‒D). Sternite V very different from that of the otherwise very similar H. anthracina from Madeira. Ovipositor of the H. vespertina type ( Fig. 8C ).

Description. Size. Wing length 4.7‒6.1 mm.

Male. Ground colour of body, antennae, palpi and legs brownish black to black, only mid and hind tibiae ochre brown to dark ochre yellow. Head uniformly brownish grey pruinose; thorax and abdomen with a strong dark shine through thin brownish grey pruinosity; a pair of narrow dark stripes between dorsocentral and acrostichal rows faintly visible on anterior half of mesonotum in posterior view; a very narrow median dark stripe is present on tergites III‒V on the abdomen. Entire wing, calypteres and halter brownish black clouded. Eye practically bare. Head with strongly holoptic eyes; frons at narrowest point only about one-third as wide as anterior ocellus, on anterior half with 3‒4 pairs of frontal setae accompanied by some setulae; width of parafacial uniform, well maintained down- wards, on middle part flexed inwards and normally concealed behind the eye in profile view. Postpedicel ca. 2.5 times longer that wide; arista plumose, but longest branches not exceeding width of postpedicel. Acrostichal setae in front of suture consisting of 4 pairs separated by finer setulae in two irregular rows; distance between acrostichal rows equals their distance to adjacent dorsocentral rows. Dorsocentral setae 2+4. Prealar seta absent. Katepisternal setae 1+2. Wing vein C without setulae on dorsal surface; Rs node without setulae. Hind tibia with 1‒2 av setae. Sternite I bare. Sternite V ( Figs 2A, B ) with uniform cover of short robust setulae. Hypopygium ( Figs 2C, D ): shape and chaetotaxy of cercus and surstylus species distinctive.

Female. Apart from usual sexual differences different from the male as follows: Abdomen with a stronger black shine through sparse dark grey pruinosity, leaving no indication of a median dark stripe. Parafacial narrowing downwards, usually narrowly visible behind eye in profile view. Distance between presutural acrostichal rows slightly wider than their distance to adjacent dorsocentral rows. Ovipositor ( Fig. 8C ) of the Hebecnema vespertina type.

Remarks. The present species belongs to the Hebecnema vespertina species group. It is easily separated from other European species of Hebecnema except the Madeiran H. anthracina by the dark calypteres. It is readily separated from H. anthracina in the male sex by the different shape and chaetotaxy of sternite V, surstyli and cerci. The females of H. anthracina and H. anthracinella sp. nov. are presently inseparable unless their provenance is known.

Distribution. Canary Islands: Gran Canaria, Tenerife, La Gomera, La Palma. Endemic to the western Canary Islands.

Figures

FIGURE 2. Hebecnema anthracinella sp. nov. Male terminalia. A, B. Sternite V in ventral and lateral views. C, D. Cerci, surstyli and epandrium in posterior and lateral views.

FIGURE 8. Hebecnema spp. Ovipositor, left half only, except for sternites VI and VII. A, B. H. umbratica (Meigen). C. H. anthracinella sp. nov. Abbreviations: Ce = cercus; Ep = epiproct; Hy = hypoproct; St = sternite; T = tergite.