Haloscatella Mathis

Mathis, Wayne N., Zatwarnicki, Tadeusz & Marris, John W. M., 2004, Review of unreported shore­fly genera of the tribe Scatellini from the New Zealand subregion (Diptera: Ephydridae) with description of three new species, Zootaxa 622, pp. 1-27 : 4-6

Genus Haloscatella Mathis

Haloscatella Mathis 1979: 6 [as a subgenus of Lamproscatella Hendel ; type species: Lamproscatella (Haloscatella) arichaeta Mathis , by original designation].­ Olafsson 1991: 42 [generic status].­ Mathis and Zatwarnicki 1995: 255 –256 [world catalog].

Diagnosis. Haloscatella is distinguished from other genera of Scatellini , especially those related to Lamproscatella , by the following combination of characters: coloration generally grayer and more densely microtomentose, particularly face, pleural areas and abdomen. Vestiture of mesofrons variable, but usually mostly microtomentose, appearing dull, at least thinly microtomentose, subshiny; eye wider than high, generally slightly oriented at oblique angle to oral margin; gena­to­eye ratio 0.40 or greater; posterior fronto­orbital seta inserted closer to anterior fronto­orbital seta than to inner vertical seta. Wing usually macropterous, normally developed; posterior notopleural seta inserted approximately midway between dorsal angle and posterior angle, at distinctly higher level than anterior seta; subapical scutellar seta 1/2 or less length of apical seta.

Head: Mesofrons generally dull, densely microtomentose, occasionally subshiny and thinly microtomentose, lateroclinate fronto­orbital setae 2 and 2 setulae, these slightly divergent and inserted anterior of and between larger setae, orientation of second smaller seta often at oblique angle to that of other fronto­orbital setae; ocelli arranged to form isosceles triangle, distance between posterior ocelli greater than distance between anterior ocellus and either posterior ocellus; gena­to­eye ratio 0.40 or greater; eye obliquely oriented to general plane of head; facial setae gradually longer toward oral margin; setae along oral margin only slightly longer than those above; porrect to dorsoclinate facial seta distinctive, large, near posteroventral angle of face, approximately in line with anterior margin of eye; face in profile protrudent.

Thorax: Insertion of posterior notopleural seta distinctly elevated above level of anterior seta; a distinct dorsoclinate seta toward anterodorsal corner of anepisternum; acrostichal setae weak, sparse, in 2 rows that sometimes converge or overlap each other; prescutellar acrostichal setae well developed, distinct from other acrostichal setae by being more widely set apart and slightly larger; wing mostly hyaline, some species infumate around crossveins and veins.

Abdomen: Male terminalia: Epandrium a closed plate around cercal cavity, without articulated surstyli at anterior margin; gonites elongate with narrow base, generally without setae, their posterior processes complete medially; phallapodeme in lateral view curved; dorsal aedeagal opening without fold along ventral margin; some species with distiphallus; distiphallus, if present, with membranous ventral elongate process that originates from distal aedeagal margin, covered by short, sharp scales or scale­like thorns; ejaculatory apodeme lacking.

Natural History. Haloscatella is distinctly halophilous and seems to proliferate best where saline or alkaline conditions are near saturation. In late summer, when the water level has lowered and exposed more shoreline around many of the shallow lakes of western North America, species of this genus are often found in great abundance. As the newly exposed shoreline dries, a white, crystalline layer of salt is formed on the surface, and cracks begin breaking the upper layers of sediment into smaller portions. Within the cracks thousands of flies are frequently encountered. The cracks probably provide protection from heat, and in their bottoms is the only nearby source of moisture. Scheiring and Foote (1973) also collected Haloscatella from small pools of saline water formed from the drainage of a large brine storage and salt plant near Rittman, Ohio.

Discussion. With the exception of H. dichaeta (Loew) , which is found in the Palearctic and Afrotropical Regions, and the three species described herein, this genus occurs exclusively in the Western Hemisphere. Their present center of diversity is western North America, where most species have widespread distributions ( Mathis 1979). Although some species occur along the coasts, they are also abundant inland, especially around the salt­caked shores of shallow saline or alkaline lakes.

The species of Haloscatella from the Western Hemisphere and H. dichaeta are somewhat homogeneous in overall appearance and are unlikely to be confused with other genera. The precedent of homogeneity, however, does not characterize the three species described below. Each is markedly different from each other externally with only H. karekare being superficially similar to congeners from western North America. Despite the lack of external homogeneity, we place the three New Zealand species in Haloscatella primarily based on external characters, especially the number of fronto­orbital setae, lack of a genal seta, bare or macropubescent arista and the number of dorsocentral setae. Some structures of the male terminalia, however, such as the cuticular thorns on the distiphallus, are also features of the genus Philotelma Becker.