Scatellini

Costa, Daniel N. R., Mathis, Wayne N., Marinoni, Luciane & Sepúlveda, Tatiana A., 2024, Phylogeny and taxonomy of the shore-fly tribe Scatellini (Diptera: Ephydridae: Ephydrinae), Zoologia (e 23100) 41, pp. 1-35 : 8-10

Scatellini Wirth & Stone, 1956

Scatellini Wirth and Stone 1956: 466. Type genus: Scatella Robineau-Desvoidy, 1830 . – Olafsson 1991: 55–68 [relationships among Palearctic genera]. – Zatwarnicki 1992: 66–119 [phylogeny and classification]. – Mathis and Zatwarnicki 1995: 254–288 [world catalog]. – Mathis et al. 2014: 561–576 [review of genera and species from Brazil].

Description. Specimens of Scatellini may be distinguished from other Ephydridae by the following combination of character states: Body length 0.80–5.00 mm; generally dark brown to cinereous (rarely yellow), microtomentose to shiny. Posterodorsal arm of the gonite present and aedeagus with slipper or shoe-like shape.

Head: Mesofrons subquadrate, slightly wider posteriorly, with dull, densely microtomentose to shiny, with metallic luster; lacking interfrontal setae; usually 2 lateroclinate, fronto-orbital setae (most genera) or 1 ( Limnellia , Scatophila ). Antenna relatively short; arista essentially bare, macropubescent (most genera) or bearing long dorsal rays ( Philotelma ); pedicel with a row of setae along anterior margin, setae longer ventrally plus 1 proclinate and 1 vertical seta dorsally. Face protuberant, setulose to moderately densely pilose, marginal setae usually larger; dorsum of interfoveal hump usually similar to rest of face, dark colored in a few species, not shiny; eye bare, usually as long as high, nearly round to obliquely oval, generally oriented obliquely to plane of epistoma; gena short to high, usually bearing a genal seta (most genera) or lacking ( Haloscatella , Lamproscatella , Philotelma , Thinoscatella ); oral opening moderately large, gaping, usually concealing clypeus; oral opening moderately large, gaping, usually concealing clypeus; maxillary palpus long and slender; mediproboscis with small sclerite laterally ( Scatella , Thinoscatella ); labellum not overlapping the mentum posteriorly.

Thorax: Dorsocentral setae 2–3 (0+2, 1+2), some setae sometimes weakly developed, the posteriormost seta displaced laterally from alignment of others; postpronotum sometimes with 1 long setae (Parascatella); row of small intra-alar setae present; intrapostalar setae small, weakly developed; presutural supra-alar seta present, variable, subequal or larger than anterior notopleural seta; postsutural supra-alar setae small than postalar seta or subequal in length (Parascatella); 2 notopleural setae, placement of posterior seta variable, usually at same level as anterior seta; proepisternum lacking setae but often with a few setulae (Parascatella); prosternum bare of setae or setulae; anepisternum bearing 1 large seta just dorsad of midheight along posterior margin, several smaller setulae may also be present; anepimeron, meron, and metapleuron bare of setae. Wing hyaline to conspicuously infuscate with or without white spots; costal vein extended to vein M 1 (most genera) or to vein R 4+5 ( Scatophila ); crossvein r-m just posteriorly to distinctly distal to subcostal break ( Haloscatella [species from New Zealand], Philotelma , Limnellia , Scatophila ) vein R 2+3 usually long, terminating at approximately same distance from vein R 4+5 as tip of vein M 1 is from vein R 4+5. Hindcoxal strap not setose; pulvilli normally developed; tarsal claws short, curved.

Abdomen: Male with 5 visible abdominal tergites; tergite 5 distinctly trapezoidal or triangular; sternites 5 and 6 well developed, very small or absent; female with 7 visible tergites; tergite 5 subtrapezoidal, not triangular. Male terminalia: surstylus usually fused with ventral margin of epandrium and not evident (most genera) or evident as lobes, perhaps secondarily developed; aedeagus usually a sclerotized structure shoe-shaped (apparently basiphallus) ( Amalopteryx Eaton , Haloscatella [other than New Zealand species], Lamproscatella , Limnellia , Scatella , Scatophila , Thinoscatella ) or with a sclerotized basiphallus and a membranous distiphallus invested with short, sharp scales or scale-like thorns (some Haloscatella [species from New Zealand], Philotelma ); ejaculatory apodeme lacking ( Amalopteryx , Haloscatella , Lamproscatella , Limnellia , Philotelma , Scatophila , Thinoscatella ) or present (as an L-shaped, dorsoventrally flattened structure or a crescent shaped, laterally flattened structure) ( Apulvillus Malloch , Parascatella Cresson, Scatella , Synhoplos Lamb , Teichomyza Macquart ); phallapodeme rudimentary, like a laterally flattened bow ( Haloscatella , Lamproscatella , Haloscatella [other than New Zealand species]) or rod-like, lacking a keel ( Amalopteryx , Haloscatella [ New Zealand species], Limnellia , Philotelma , Scatophila ) or greatly reduced or lacking ( Apulvillus , Parascatella, Scatella , Synhoplos , Teichomyza ); gonites and hypandrium fused forming a single structure (“gonal arch”) ( Amalopteryx , Haloscatella , Lamproscatella , Thinoscatella , Apulvillus , Parascatella, Scatella , Synhoplos , Teichomyza , ground plan of Limnellia ) or separated into medial sclerite “hypandrium” and lateral structures representing gonites ( Philotelma , New Zealand Haloscatella , most Scatophila ) or separated medioventrally into 2 lateral structures “gonites” (most Limnellia ) (2 separate gonites are present also in some Scatophila (avida group), in which the “hypandrium” is reduced. Female Terminalia: sternite 7 as one rectangular sclerite or 2 lateral, small, circular to partially quadrate sclerites; sternite 8 divided into 2 sclerites; cerci bearing one prominent seta, strong or weak, inserted posteroventrally or without prominent setae; sternite 9/subanal plate without strong setae; operculum present or absent, when present helmet-like or tubular shaped.

Natural history. Foote (1995) compiled and summarized information about the natural history of Scatellini that was extracted from numerous articles that treated various included species. The species of Scatellini generally feed on algae, cyanobacteria and particles of various types of decomposing animal and plant organic matter, as well as various microorganisms that proliferate on that substrate. Species of Scatellini live in a wide variety of habitats, such as hot springs and alkaline or acid lakes (some species of Haloscatella , Scatella , Neoscatella , Scatophila ); marshes, mangroves, intertidal areas, dunes and sandy beaches, rocky coasts and other localities with large concentrations of salt. They also occur in muddy and sandy habitats along riverbanks and lakes. Some species are found on urban lawns. Scatella stagnalis ( Fallén, 1813) is often found in greenhouses and is the vector of a root disease caused by a Pythium fungus to crops in hydroponic cultures ( Goldberg and Stanghellini 1990). The larvae of one species, Scatella (Teichomyza) fusca Macquart, 1835 , occur in an unusual environment: localities and habitats that are soaked in urine, such as outdoor urinals. The larvae and adults of this species feed on human and animal excrement ( Vibe-Petersen 1998). This is also the only known species of the family Ephydridae that has been implicated in cases of myiasis ( James 1947).

Among all shore flies, Scatellini also includes a disproportionate number of species with reduced wings. We have thus far discovered 34 shore-fly species that have reduced wings to some degree ( Costa et al. 2016, Krivosheina and Ozerov 2016, per. obs.), with a preponderance of these, 20 species, occurring in Scatellini . Two monotypic genera in Scatellini are in fact characterized by reduced wings: Amalopteryx ( A. maritima Eaton ), and Tauromima ( T. mountwilhelmi Papp ). Species of Diptera with reduced wings occur more often in specific environments, such as oceanic islands, mountainous areas of high elevation, arctic and sub-Antarctic areas of low altitude, coastal and marine habitats; those not in these categories are species with terricolous or hypogenous habits, are ectoparasites or they live in social insect nests ( Hackman 1964, Roff 1990). These environments and the natural history of these groups promotes the emergence of several features common to these flies by convergent evolution, such as reduction of thoraces and halteres, strong legs, and large abdomens, besides the reduction and/or loss of wings ( Wagner and Liebherr 1992).

Distribution. Worldwide there are 247 species in Scatellini ( Mathis and Zatwarnicki 1995). This speciose tribe occurs in all biogeographic regions except Antarctica. Many of the nine included genera ( Amalopteryx , Haloscatella , Lamproscatella , Limnellia , Philotelma , Scatella [subgenera: Apulvillus , Parascatella, Scatella , Synhoplos , Teichomyza ], Scatophila , Tauromima , Thinoscatella ) are found throughout the world in temperate and tropical zones, particularly on shorelines and beaches.

In the Neotropical Region, which has numerous undescribed species, we have discovered considerable species diversity at higher elevations and associated with the Andes Mountains. In Colombia, for example, we collected specimens above 5000 m, (WNM, pers. obs.). There is also considerable diversity worldwide along maritime seashores in temperate and tropical zones. This range in elevation, from sea level to over 5000 m, is matched by few other tribes in Diptera .