Eosalpingogaster nepenthe (Hull)

General description:

Eosalpingogaster and Salpingogaster are readily distinguished from all other syrphine groups by the presence of distinct black spinose bristles on the metafemur combined with the petiolate abdomen and sinuate vein R4+5. Both genera have petiolate abdomens, but Salpingogaster is distinguished from Eosalpingogaster by the much more greatly sinuate vein R4+5; other syrphines with sinuate vein R4+5 have oval abdomens. Eosalpingogaster has 1st tergum not produced into a spur, vein R4+5 only slightly sinuate and occipital cilia in 3–4 rows dorsally. In contrast, Salpingogaster has 1st tergum produced laterally into a strong spur and occipital cilia reduced to a single row dorsally.

E. nepenthe is a very light species with pleuron, legs and 2nd abdominal tergum brownish red instead of black, as the rest of species. It has 3rd tegum also distinct with yellow fascia on basal 1/3 extending apically on lateral margins, and wing veins bordered with brown except apically.

Diagnostic description:

Similar to E. cochenillivora, but differs by having pleuron, legs and 2nd abdominal tergum brownish red instead of black, with posterior anepisternum yellow on posterior half and katepisternum with dorsal yellow macula; and wing with broader brown area on anterior margin, with 2nd costal cell entirely microtrichose and brown (in males and females). It has 3rd tegum also distinct with yellow fascia on basal 1/3 extending apically on lateral margins.

Size:

Length (3): body, 11.9–12.2 (12.1) mm; wing, 8.7–9.2 (8.8) mm.

Evolution:

Eosalpingogaster conopida was the only species included in the molecular phylogeny by Mengual et al. (2008a). In their analysis, Eosalpingogaster was resolved as sister group of Ocyptamus melanorrhinus, embedded in a clade formed by Ocyptamus and Toxomerus species. This placement was recovered again in Mengual et al. (2008b) when they used them as outgroup for Allograpta.

Eosalpingogaster was proposed by Hull (1949: 299) as a new subgenus of Salpingogaster Schiner. Hull based his decision on the absence of a sharp hook on anterior corners of the first abdominal segment and on the slight curvature of vein R4+5. In contrast, the species of the genus Salpingogaster have the first abdominal tergum produced laterally into a strong spur and vein R4+5 strongly sinuate.

Eosalpingogaster larvae are predators of scale insects (Coccoidea), in contrast with the larvae of Salpingogaster, which feed on spittlebugs (family Cercopidae).

The results from the molecular analysis by Mengual (Mengual and Thompson 2011) resolved Eosalpingogaster and Salpingogaster in two different clades, independent of the method used to infer the phylogeny, and they considered Eosalpingogaster as a valid genus.

A similar result was obtained by Mengual et al. (2012).

Associations:

Type material was reared from larvae found feeding on Dactylopius tomentosus (Lamarck) and the male specimen from Big Pine Key was reared from a larva preying on Dactylopius.

Distribution:

Eosalpingogaster nepenthe is only known from Florida (USA).

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Eosalpingogaster nepenthe (Hull)

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