Megapropodiphora arnoldi Brown 2018

Brown, Brian V., 2018, A second contender for " world's smallest fly " (Diptera: Phoridae), Biodiversity Data Journal 6, pp. 22396-22396 : 22396

Megapropodiphora arnoldi Brown 2018 sp. n.

Materials

Type status: Holotype. Occurrence: recordedBy: D. Amorim, J. Raphael; sex: female; lifeStage: adult; preparations: mounted on slide in Canada Balsam by B. Browns; Taxon: genus: Megapropodiphora; specificEpithet: arnoldi; scientificNameAuthorship: Brown 2018; Location: country: Brazil; stateProvince: Amazonas; locality: 12 km S Novo Airao ; verbatimElevation: 34 m; locationRemarks: forest; decimalLatitude: -02.71; decimalLongitude: -60.95; Event: samplingProtocol: Malaise trap; eventDate: 2013-12-08 / 2013-12-09 Type status: Holotype. Occurrence: otherCatalogNumbers: LACM ENT 334268

Description

Female (Figs 2, 3). Body length 0.395 mm, flattened, limuoid. Flagellomere 1 pointed, with long setae almost as long as flagellomere 1 + apparently 2-articled arista (difficult to discern due to small size of specimen). Palpus large, broad with apical setae. Proboscis greatly reduced. Genal margin with few setae. Frons broad, without differentiated bristle-like setae; eye greatly reduced to few ommatidia. Scutum with short sparse setae dorsally. Scutellum with 2 pairs of large setae. Forelegs, especially forecoxa, greatly enlarged; forefemur with three anteroventral setae. Mid- and hind legs greatly reduced, possibly vestigial. Abdomen extremely small, covered by scutellum. Oviscape pointed.

Male unknown (but see below).

Diagnosis

Female. Minute, limuloid; body setae scattered, sparse; wing with shed blades and short costa; head and scutum large, scutellum covering almost entire abdomen; oviscape thin, pointed, indicating a parasitoid lifestyle. Edge of scutum lateroventrally extended, posteriorly ending in narrowed flange (Fig. 4). Forelegs greatly enlarged; mid- and hind legs reduced.

Similar genera. Males of Brachycosta Prado, 1976, have a short costa, but much longer than that of Megapropodiphora gen. n., are much larger in size and have a larger frons and head. Females of this new genus are differentiated from all other phorids by minute size, leg structure and elongation of the scutellum to cover the abdomen.

Etymology

The genus name is Latin for large foreleg, referring to the structure of the female. The specific epithet refers to Arnold Schwarzenegger, former governor of California, whose own greatly enlarged forelimbs distinguished him in his pre-political careers.

Distribution

Amazonian Brazil

Biology

Unknown, but almost certainly a parasitoid. The torn wing membrane is reminiscent of other phorid flies that shed their wings when entering a social insect colony. It seems likely that the greatly enlarged forelegs are used to clutch a host, upon which the small, rounded body would appear similar to that of many phoretic mites.

Notes

A potential male specimen was accidentally destroyed during illustration process, but from memory only, it was as follows: minute, with small head; frons greatly reduced (as in male Chonocephalus Wandolleck, 1989) and extremely reduced head setae; wing with short costa and large blade. Lacking further information, I cannot assign this new genus and species to any subfamily.

It is common for researchers to change the alcohol in Malaise trap samples, pouring off the old liquid, stained yellow with body fluids of the many preserved insects. Also, we commonly drain the alcohol out of samples for safer or at least more legal transport of these chemicals. Fortunately, the samples including the M. arnoldi sp. n. were examined immediately after being collected and were thus not so treated. The tiny phorid flies described herein are easily lost when waste alcohol is drained off, such that any alcohol that is being disposed should be first examined carefully under a microscope. Furthermore, I suggest purposely “washing” Malaise trap samples in fresh alcohol to clean tiny insects off of the larger ones and search for further microfauna.