Haloscatella harrisoni, Mathis, Wayne N., Zatwarnicki, Tadeusz & Marris, John W. M., 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 : 10-14

Haloscatella harrisoni sp. nov. ( Figs. 10–12 , 14 )

Diagnosis. This species is distinguished from congeners by the following characters: Small shore flies, body length 1.50–1.60 mm; generally brown to grayish brown with some bluish luster on pleural area and abdominal tergites; genal seta lacking, and wing brachypterous; bearing a large seta at subcostal break on anterior margin; abdominal tergites sparsely microtomentose, at least partially subshiny, uniformly bluish gray to brownish gray.

Description. Head: Frons generally microtomentose, appearing dull; mesofrons blackish brown with some grayish on posterior surface of vertex; parafrons more charcoal colored; fronto­orbits blackish brown; 2 fronto­orbital setae, posterior seta much larger, lateroclinate; anterior fronto­orbital seta proclinate, shorter, length about 1/4–1/3 lateroclinate seta. Antenna with scape and pedicel black, 1st flagellomere with base yellowish or orange, apical 2/3 black; arista moderately long, length equal to combined length of first 3 segments. Face uniformly gray to bluish gray; facial setae along peristomal margin well developed, ventroclinate, bearing 2–4 large setae along margin of facial protuberance. Eye higher than wide; eye ratio 0.74–0.78. Gena moderately low, gena­to­eye ratio 0.13–0.14; gena bearing setulae along ventral margin but lacking a large, genal seta.

Thorax: Mesonotum vittate, with dark brown stripes through acrostichal and dorsocentral tracks and with gray stripes between, especially evident presuturally; acrostichal setulae in 2 approximate rows, extended over most of scutal length, no presutural seta well developed, posteriormost pair slightly larger than anterior setulae; apical scutellar seta twice length of basal seta; posterior notopleural seta with elevated insertion compared to anterior seta; pleural areas mostly bluish gray, microtomentose; anepisternum with 1 porrect to slightly dorsoclinate seta at anterodorsal corner, this seta subequal to seta along posterior margin. Wing ( Fig. 14 ) brachypterous, pointed, length about 0.75 mm; bearing a large seta at subcostal break on anterior margin. Legs with femora and tibiae grayish black to black; tarsi brownish black to black with some yellowish coloration basoventrally.

Abdomen: Tergites sparsely microtomentose, at least partially subshiny, uniformly bluish gray to brownish gray. Male terminalia ( Figs. 10–12 ): Epandrium in ventral view ( Fig. 10 ) broadly oval, bearing a few setulae submarginally and toward venter; ventral margin somewhat extended as 2 shallow lobes bearing longer setulae; cerci hemispherical, evenly setulose; aedeagus with basiphallus in ventral view ( Fig. 11 , shaded) elongate, twice as long as wide, broadly pointed apically, in lateral view ( Fig. 12 , shaded) with basal 2/3 wide and broadly rounded on one surface and shallowly emarginated on opposite surface, apical 1/3 narrowed and asymmetrically pointed, distiphallus in retracted position 1.5 as long as basiphallus, the structure of its surface shown in square; phallapodeme in ventral view ( Fig. 11 ) T­shaped, in lateral view ( Fig. 12 ) a shallowly arched bar­like structure with an irregular surface on external surface toward articulation with base of aedeagus; gonite in lateral view ( Fig. 12 ) narrow, tapered to pointed apex that bears tiny setulae, in ventral view oriented medially, elongate with basal half nearly double width of apical half, hypandrium in lateral view shallowly arcuate, in ventral view ( Fig. 11 ) V­shaped.

Type material. The holotype male is labeled “ NEW ZEALAND, BO Bounty Is, Proclamation I[,] 25.xii.1997 A.M. Booth on rock face/ HOLOTYPE ɗ Haloscatella harrisoni Mathis Zatwarnicki & Marris [red].” The holotype is double mounted (minuten in a rectangular block of foam), is in good condition, and is deposited in the LUNZ. Paratypes are as follows: Same locality data and date as the holotype (2ɗ, 5Ψ; LUNZ, USNM); Depot Island (nest of Diomedea cauta salvini [= Thalassarche salvini ]; BITC 38), 18 Nov 1978, D. S. Horning (6ɗ, 3Ψ; MONZ, USNM, all but 2 ɗ in alcohol).

Distribution. Australasian/Oceanian: New Zealand (BO: Bounty Islands: Depot Island, Proclamation Island).

Remarks. This species from the Bounty Islands is known from only 17 specimens that were collected on two occasions. The Bounty Islands (47°45'S 179°02'E) lie 624 km east of Bluff on the New Zealand mainland ( Fraser 1986) and are barren, windswept, granitic outcrops that lack any permanent freshwater and are devoid of any vascular plants. These are the smallest subantarctic islands within the New Zealand subregion, with a total area of around 135 ha and include 14 named islands plus several small islets and rock stacks. The islands are composed of basement granites and are believed to be the remnants of a previously much larger land mass ( Fraser 1986). At times the islands are the home to vast numbers of nesting seabirds, including Salvin’s Mollymawk ( Thalassarche salvini (Rothschild)) and Erect­crested Penguins ( Eudyptes sclateri Buller ), and are a major breeding site for the New Zealand fur seal ( Arctocephalus forsteri (Lesson)) . Because of their remoteness, small size and difficult access, few scientific visits have been made to these islands, and as a consequence, little is known about their entomological fauna.

The terrestrial invertebrate fauna of the Bounty Islands is small but fascinating. The lack of species is not surprising given the small size of the islands and, perhaps as significant, the absence of any vascular plants. The fauna is typical of the subantarctic islands of the New Zealand subregion, with close affinities with its nearest neighbor, the Antipodes Islands, which are about 220 kilometers further south. Several species occur exclusively on the Bounty and Antipodes Islands, such as the hydrophilid beetle Tormissus guanicola (Broun) and the tineid moth Proterodesma turbotti Salmon and Bradley. Also of note is the high level of endemism among the Bounty Islands’ fauna. For example, five invertebrate genera, Pacificana Hogg ( Araneae : Miturgidae ), Ischyroplectron Hutton ( Orthoptera : Rhaphidophoridae ), Bountya Townsend ( Coleoptera : Carabidae ), Aphrosylopsis Lamb ( Diptera : Dolichopodidae ) and Sandrapsocus Smithers (Psocoptera: Elipsocidae ) are endemic to these islands.

The specimens from Depot Island were collected from an occupied nest of Salvin’s Mollymawk ( Thalassarche salvini ). The organic debris in the nest probably provided suitable substrate and food for larval development.

Haloscatella harrisoni is the sixth dipteran and the third flightless species recorded from the Bounty Islands ( Harrison 1953, 1976, Marris unpubl.). The high level (50%) of flightlessness among Diptera of the Bounty Islands is considerably greater than the 6% recorded for the slightly more southern Snares Islands and 13–15% for other New Zealand subantarctic islands ( Macfarlane and Andrew 2001).

Figures

FIGURES 10 – 12. Structures of the male terminalia of Haloscatella harrisoni (New Zealand. Bounty Islands. Proclamation Island). 10, Epandrium, and cerci, ventral view. 11, Internal genitalic structures (aedeagus (shaded), phallapodeme, gonites, and hypandrium), ventral view. 12, Same, lateral view.

FIGURES 13 – 15. Wings of Haloscatella species. 13, H. balioptera (New Zealand. Chatham Island: Tennants Lake). 14, H. harrisoni (New Zealand. Bounty Islands. Depot Island). 15, H. karekare (New Zealand. AK: Karekare).