Limnellia abbreviata (Harrison) Harrison, 2004

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 : 19-22

Limnellia abbreviata (Harrison) , new combination ( Figs. 24–27 )

Scatella abbreviata Harrison 1976: 136 .­ Horning 1977: 35 [ecology].­ Mathis 1989: 649 [Australasian/Oceanian catalog].­ Mathis and Zatwarnicki 1995: 270 [world catalog].

Diagnosis. This species is distinguished from congeners by the following characters: Wing brachypterous; small shore fly, body length 1.35 mm, body dark brown with grayish mottling, generally densely microtomentose.

Description. Head: Head ratio 0.69; mesofrons and fronto­orbits dark brown to grayish brown anteromedially; parafrons grayish brown; ocellar, both verticals and single fronto­orbital seta well developed and subequal; 2–3 lateroclinate setulae and a proclinate anterior setula that is slightly larger than other fronto­orbital setulae; inner vertical seta inserted anterior of outer seta. Scape and pedicel gray brown; 1st flagellomere yellowish orange; arista without hair­like, dorsal branches, length subequal to combined length of pedicel and 1st flagellomere. Face golden to grayish brown; face bearing 2 lateroventroclinate setae and 5 ventroclinate setae along peristomal margin; parafacial gray. Eye ratio 0.88; gena­to­eye ratio 0.08; gena with 1 large, posterior seta and 2–3 setulae anterior and posterior on postgena. Palpus blackish brown.

Thorax: Mesonotum mostly dark brown; with medial gray to whitish stripe on posterior 2/3 of scutum, slightly enlarged just before scutellum; 2 gray, elongate spots on anterior 1/3 between acrostichal and dorsocentral tracks and 1 elongate spot along dorsocentral track between setae; posterior apex of scutellum grayish; posterior notopleural seta at elevated insertion compared to anterior seta; postpronotum and posterior portion of notopleuron, extending onto supra­alar area, gray; pleurae mostly brown but dorsal margin of anepisternum and especially of katepisternum gray; only 1 anepisternal seta toward dorsum of posterior margin and 1 katepisternal seta. Wing ( Fig. 27 ) brachypterous, extended posteriorly to posterior margin of 2nd abdominal tergite. Legs with femora and tibiae blackish brown; basal 2 tarsomeres yellowish, apical 2–3 becoming increasingly more brownish distally.

Abdomen: Tergites mottled, mostly brown with gray spots or longitudinally linear marks, becoming increasingly grayer on more posterior tergites; tergites 3–5 with medial gray area and with gray surrounding brown spot just laterad of midline. Male terminalia ( Figs. 24–26 ): Epandrium in ventral view ( Fig. 24 ) broadly oval, lateral margins almost parallel sided, ventral margin broadly emarginate into which surstyli are based, evenly setulose; cerci with ventral angle more acute than dorsal angle but otherwise hemispherical, more setulose toward medial margin; surstyli in ventral view ( Fig. 24 ) somewhat triangular, bearing longer setulae along ventral margin but with several very short setulae apically; aedeagus (shaded) in ventral view ( Fig. 25 ) like a top with base wide and apex pointed, in lateral view ( Fig. 26 ) almost evenly wide although dorsal and ventral margins irregular, with a sub­basal, rounded notch dorsally, apex irregularly incised; phallapodeme in lateral view ( Fig. 26 ) long and narrow, margin irregular, in ventral view ( Fig. 25 ) Tshaped with basal bar shallowly flared, medial arm wider at articulation with base of aedeagus; gonite in lateral view ( Fig. 26 ) wide basally, apical 2/3 narrow, slightly curved, apex tapered to rounded point, in ventral view ( Fig. 25 ) apical projection becoming slightly wider apically but with an abruptly tapered, pointed apex; posterior projection forming an arch.

Type material. The holotype male is labeled “U. of C[anterbury]. ZOOLOGY DEPT. Loc.: opp. Mollymawk Inlet. SNARES IS. Hab.beating Poa astoni Date: 24­I­67 [24 Jan 1967] Coll.: P[eter].M.J[ohns] [white; details on locality, habitat, date and collector handwritten] / HOLOTYPE Scatella abbreviata ɗ det. R.A.Harrison [white; handwritten].” The holotype is preserved in alcohol, is in good condition, and is deposited in NZAC. There are also five female paratypes that are preserved in a separate tube of alcohol ( NZAC).

Other specimens examined. New Zealand. Snares Islands: South side Ho Ho Bay (on damp peat in sooty shearwater run), 11 Jan 1975, C. J. Horning (1ɗ; NZAC); Sinkhole (drainage area on rock face), J. W. Early (3ɗ, 7Ψ; AMNZ).

Distribution. Australasian/Oceanian: New Zealand (Snares Islands).

Natural history. Horning (1977) reported rearing this species from seepage sites on Snares Islands.

Remarks. This is the only known brachypterous species of Limnellia and is distinguished from congeners by the brachypterous wing and structures of the male terminalia ( Figs. 24–26 ).

When Harrison (1976) described this species he misinterpreted the number of lateroclinate fronto­orbital setae and thus misidentified the genus. The genus Scatella does indeed have two fronto­orbital setae, but specimens of S. abbreviata , including the holotype, have a single well­developed lateroclinate seta, and thus, Harrison’s statement (1976: 136) “By definition this species is a true Scatella ” is incorrect. Only two genera, Limnellia and Scatophila , of the tribe Scatellini have a single fronto­orbital seta, and species of these two genera with normally developed wings can be distinguished by the length of the costal vein (the costal vein is short in Scatophila , extending only to vein R4+5, and in Limnellia it extends to vein M). With a brachypterous wing and greatly reduced venation, as in this species, this character is impossible to use, and we had to rely primarily on structures of the male terminalia, especially the articulated surstyli at the ventral margin of the epandrium, to make the generic assignment.

Figures

FIGURES 24 – 26. Structures of the male terminalia of Limnellia abbreviata (New Zealand. Snares Islands: south side of Ho Ho Bay). 24, Epandrium, cerci, and surstylus, ventral view. 25, Internal genitalic structures (aedeagus (shaded), phallapodeme, and gonite), ventral view. 26, Same, lateral view.

FIGURES 27 – 28. Wings of Limnellia species. 27, L. abbreviata (New Zealand. Snares Islands: Sinkhole). 28, L. maculipennis (New Zealand. Hamilton, McKenzies Bush, Dinsdale).