Baccha elongata (Fabricius, 1775):768

Species extremely slender with petiolate abdomen at least 25 times as long as its least subbasal width; wings clear or with very faint brownish markings (Vockeroth 1992).

Baccha elongata (Fabricius, 1775).

Fabricius, J.C. (1775) Systema entomologiae, sistens insectorum classes, ordines, genera, species, adiectis synonymis, locis, descriptionibus, observationibus. Kortii, Flensbvrgi et Lipsiae [= Flensburg & Leipzig]. [32] + 832 p. [1775.04.17]

New description:

Head: Frons and face black, yellow in the ventral part between eye margin and mouth ventrad to facial tubercle, mostly white pruinose except facial tubercle and lunule shiny black, yellowish pilose. Face narrow, slightly receding below, with low distinct tubercle; margin of subcranial cavity curved strongly upward. Gena very narrow, black, white pilose. Antenna brown, very short, basoflagellomere oval to round, lighter ventrally; occiput black, silver pollinose, withish-yellow pilose, most external row with long pili.

Thorax: Scutum mostly shiny black, lightly pruinose anteriorly and laterally, with short yellowish pile; postpronotum yellowish, bare; postalar callus dark brwon; scutellum black, yellowish pilose, with sparse ventral scutellar fringe only laterally. Pleura mostly weakly pruinose, black, some specimens lighter on dorsal half close to wing base; anterior anepisternum, meron, metathoracic pleuron and metasternum bare; dorsal and ventral katepisternal hair patches widely separated. Postmetacoxal bridge entire. Calypter, plumula and halter yellow; spiracular fringes yellow. Wing almost entirely microtrichose except basal 1/4 of cells C, R, BM and CuP. Alula bare, much narrower than 2nd costal cell, anal lobe reduced; crossveins and extreme apex of wing faintly clouded in some specimens. Legs: eniterly yellow except metacoxa and metatrochnater brown, and metatarsus brown, yellow pilose; metacoxa without posteromedial apical hair tuft.

Abdomen greatly elongated (in males about 40 times as long), narrow, as least width of 2nd tergum; 2nd and 3rd terga much narrower thna scutellum; dark brown to black; 2nd tergum with narrow yellow anterolateral maculae; 3rd and 4th terga with short basal yellow fascia, some specimens without fascia on 3rd tergum.

FEMALE.

Similar to male except for normal sexual dimorphism and as follows: frons white pollinose laterally except a shiny black medial vitta from lunule to ocellar triangle; abdomen at least 25 times as long, reddish towards apex in some specimens; 5th tergum in females with very narrow yellow fascia on anterior margin or with pair of small anterolateral yellow maculae.

Some authors have recognized two species of Baccha, B. elongata (Fabricius) and B. obscuripennis Meigen, based on the presence/absence of dust on the frons of the male. Males of B. elongata usually have dust on the frontal triangle.

Synonyms:

Syrphus elongatus Fabricius, 1775: 768.

Baccha obscuricornis Loew, 1863: 15.

Baccha cognata Loew, 1863: 15.

Baccha angusta Osten Sacken, 1877: 332.

Baccha tricincta Bigot, 1883: 333.

Baccha karpatica Violovitsh, 1976: 138.

Baccha abbreviata Meigen, 1822: 200.

Musca erratica Scopoli, 1763: 345.

Baccha klugii Meigen: 1830, 349.

Baccha nigricornis Schummel, 1841: 169.

Baccha nigripennis Meigen, 1822: 200.

Baccha scutellata Meigen, 1822: 198.

Baccha sphegina Meigen, 1822: 198.

Baccha tabida Meigen, 1822: 199.

Baccha vitripennis Meigen, 1822: 200.

Musca elongata Schrank, 1803: 108.

GenBank accession number for this species are: protein-coding COI gene (EF127326; AY261707), rRNA 28S gene (EF127407; AY261754) and 18S gene (EU431540).

Body length: 7.2-10.2 mm.

Baccha elongata is a member of the tribe Bacchini, subfamily Syrphinae, and its phylogenetic position is unstable. Mengual et al. (2008) reported B. elongata as sister group o the tribe Pipizini. But most of the times, DNA analysis resolve this taxon alone as sister group of the tribes Paragini, Toxomerini and Syrphini; separated from the rest of Bacchini.

Larvae of B. elongata have been reported feeding on aphids (Aphididae) and on larvae of Lepidoptera (Mamestra persicae) (Rojo et al. 2003).

Adults visit flowers of Compositae, Rosaceae and Umbelliferae, Hedera etc. (Speight 2010). Dussaix (2005a) reared the species from larvae found on Aquilegia, Digitalis, Euphorbia, Hieracium, Hypochaeris, Sambucus nigra and Sonchus.

The flight period for this species is April/June and July/September or October (Speight 2010).

Baccha elongata is a widespread Holarctic species. In the Nearctic, it appears from Alaska to Nova Scotia, south to California, Ohio, and Virginia (Vockeroth 1992). In Europe from Scandinavia to the Mediterranean; central Spain eastwards to Greece and Ireland eastwards into European parts of Russia (Speight 2010). This species is also known from the Azores (Rojo et al, 1997).

Preferred environment: forest, both coniferous and deciduous, both young and old; also in scrub woodland, hedgerows and suburban gardens (Speight 2010).

Adult habitat and habits: flies within woodland, usually within 1-3 metres of the ground and as much in the shade as in the sun; seldom ventures far into open areas (Speight 2010).

Egg (from Chandler 1968 as B. obscuripennis):

White, greying slightly on development; mean length 1051 µ (n = 44, range 990-1135 µ), mean width 400 µ; rather bulbous, rounded at both ends; surface patterning of rows of inconspicuous, small whitish striations very slightly upraised. Chorionic sculpturing: dorsally, axes with side-branches only ccasionally in contact with those of neighbouring units; slight, non-particulate central areas, axes clearly visible; ventrally, groups of dots and rods. Ecological notes. Frequent; eggs found from May to October, with peaks in May and August-September; adult habitat preference for shaded regions; wide host acceptance range; eggs laid singly.

Third instar larva (from Dixon 1960):

Average length 9.5 mm., width 1.5 mm., height 1 mm. ; pale grey with a buff pink longitudinal band on either side of heart line extending laterally to dorsolateral ridges, and joined along median line on segment 4; each band divided and divergent posteriorly from segment 10 and anteriorly from segment 8; salivary glands faintly visible on segment 4; subcylindrical, tapering anteriorly, cuspidate posteriorly ; a dorsolateral longitudinal ridge on either side of the body; transversely wrinkled; fleshy projectjona and prominences absent; prolegs and claws absent; integumental vestiture absent; segmental ornamentation of microscopic pointed hairs mounted on individual papillae; external mouth hooks present; aphidophagous. Posterior respiratory process: postero-dorsal, almost as long as broad; spiracular plates separated by a median groove; circular plates oval to kidney-shaped, median and anterior to inner ends of spiracles I; dorsal spurs present as short inconspicuous folds well separated and median to circular plates; interspiracular ornamentation of five pairs of openings, two pairs of openings between spiracles I and II; three pairs of short, straight, spiracles four times as long as wide not mounted on carinae, and situated on areas sometimes pale and sometimes black; spiracles radiating on these areas.