Trivialia, Malloch, 1923

Gaimari, Stephen D. & Soares, Matheus M. M., 2022, Unusual sexually dimorphic head morphology in Lauxaniidae (Diptera: Lauxanioidea) - a new species of the genus Trivialia Malloch from Peru, Zootaxa 5120 (3), pp. 391-401 : 392-393

TRIVIALIA Malloch

Trivialia Malloch, 1923: 53 (as subgenus of Deceia Malloch, 1923 ).

Type species. Deceia fuscocapitata Malloch, 1923: 53 (original designation).

Diagnosis. This genus can be differentiated from other lauxaniids by the following combination of characteristics. On the head, the frons is broader than long, bare of setulae, with the fronto-orbital setae reclinate and strong, with the posterior seta stronger. The ocellar setae are short and divergent, shorter than the postocellar setae. The eyes are almost round and are not narrowed below. The face is flat and dull (not glossy). The antennal first flagellomere is black, and the arista is short plumose with the basal-most dorsal rays usually the longest, and with shorter rays below. The scutum has 2 pairs of postsutural dorsocentral setae (and no presutural dorsocentral setae), with the anterior seta at about the midpoint between the posterior seta and the transverse suture. The postsutural intra-alar seta is absent (i.e., this genus is not in the Minettia group of genera). The anterior scutellar setae are parallel to slightly convergent, while the posterior scutellar setae are divergent. On the pleuron, the anepimeron is bare and there is 1 strong katepisternal seta (sometimes with an additional weaker seta anteriorly). On the wing, the costal setulae end well before the apex of R 4+5 (as is typical in Lauxaniinae ), and the R veins are bare.

Immatures. Unknown for the genus.

Distribution. North America ( USA [eastern, Virginia south to Florida]), West Indies ( St. Vincent), Central America ( Costa Rica, Panama), South America ( Colombia, Ecuador, Peru [new record]).

Remarks. Stuckenberg (1971) and Shewell (1987) considered this an endemic Nearctic genus. Besides being included in the key to Nearctic genera, Shewell (1987) provided a figure of the lateral head of the type species, Trivialia fuscocapitata Malloch, 1923 , which was also included in Gaimari & Silva (2010a). Photographs (lateral and dorsal habitus and oblique head) of the lectotype of one of the included species, Trivialia venusta ( Williston, 1896) , was also provided by Gaimari & Silva (2020).