Limnellia Malloch

Genus Limnellia Malloch

Limnellia Malloch 1925: 331. Type species: Limnellia maculipennis Malloch 1925, original designation.­ Mathis 1989: 648 [Australasian/Oceanian catalog].­ Mathis and Zatwarnicki 1995: 258 –261 [world catalog].

Diagnosis. Limnellia is distinguished from other genera of the tribe Scatellini by the following characters: Small to moderately small shore flies, body length 1.25–2.50 mm; mostly dark brown to black, microtomentose to bare, shiny, frequently with cinereous guttate and vittate maculae; wing maculate, generally dark with white spots.

Head: Mesofrons distinct from duller parafrons, sometimes subshiny; lateroclinate fronto­orbital seta 1; inner and outer vertical setae both well developed; paravertical setae either reduced or absent; ocelli arranged in isosceles or equilateral triangle. Arista at most macropubescent. Face with shallow antennal grooves; interfoveal carina not projected or creased dorsally; facial setae mostly small, hair­like. Eye nearly round. Gena relatively short, bearing 1 well­developed seta.

Thorax: Acrostichal setae uniform in size, small, arranged in 2 rows that extend to base of scutellum; dorsocentral setae 2 (0+2); supra­alar seta either reduced or lacking; disc of scutellum bare; lateral scutellar setae 2. Wing maculate, mostly dark brown with white, generally guttate markings.

Abdomen: Tergites black, becoming shiny and polished posteriorly. Male terminalia: Epandrium a closed plate around cercal cavity, bearing articulated surstyli on anterior margin; gonites elongate with broad base, bearing setae on ventral portion; phallapodeme in lateral view nearly straight or deflected medially; dorsal aedeagal opening with a fold along ventral margin; aedeagus without distiphallus; ejaculatory apodeme usually present, small.

Discussion. Limnellia includes 18 species worldwide (Mathis and Zatwarnicki 1995) that occur in most temperate regions or at higher elevation in subtropical and tropical zones.

Although now stable, the early nomenclatural history of Limnellia reflects a lack of communications and our very fragmentary knowledge about these shore flies on a world basis. Malloch (1925) first described Limnellia from a female specimen collected in Sydney, Australia. Just five years later Cresson (1930) and Collin (1930), in separate but coincidental publications, redescribed the genus as Eustigoptera and Stictoscatella respectively. Both Cresson and Collin based their genus­group names on the same generitype, Notiphila quadrata Fallén (1813). Although Fallén's species was originally known only from Scandinavia, it is now known to be Holarctic in distribution (Mathis 1978, Mathis and Zatwarnicki 1995) but is obviously quite disjunct from the southeastern coast of Australia where its congener, which is the generitype of Limnellia, is found. Duda (1942), in an unusual paper from the standpoint of nomenclature, redescribed Limnellia yet again, this time as the subgenus Stranditella of the genus Lamproscatella Hendel. Duda also based Stranditella on the generitype, Notiphila quadrata. Duda's paper is unconventional in having most of the new genus­group and several of the included new species names as patronyms, all based on his colleague, Embrik Strand (1876–1953).