Ephydrella macquariensis (Womersley)

Mathis, Wayne N. & Zatwarnicki, Tadeusz, 2025, A review of Ephydrella Tonnoir and Malloch from the New Zealand subregion (Diptera: Ephydridae) with description of a new species, Zootaxa 5673 (2), pp. 227-251 : 239-241

4. Ephydrella macquariensis (Womersley)

Figs. 24–30

Ephydra macquariensis Womersley 1937: 77 .

Ephydrella macquariensis .— Wirth 1962: 971 [generic combination].— Watson 1967: 32 [review].— Mathis 1989: 647 [Australasian/Oceanian catalog].— Marchant and Lillywhite 1994: 471–481 [list].— Mathis and Zatwarnicki 1995: 247– 248 [world catalog].

Diagnosis.—This species is distinguished from congeners by the following combination of characters:Moderately large species, body length 4.20–4.95 mm. Associated with freshwater to slightly brackish water habitats.

Head ( Figs. 24–26 ): Frons with mesofrons mostly shiny, metallic bronze to dark, greenish bronze, lacking distinctive gray areas laterally; parafrons mostly velvety black posteriorly, black areas lunate shaped immediately adjacent to lateral margin of mesofrons, gray on anterior third to half; fronto-orbits dark gray, grayish brown adjacent to parafrons, finely but densely microtomentose. Ocelli arranged in isosceles triangle, distance between posterior ocelli conspicuously shorter than between a posterior ocellus and anterior ocellus. Antenna grayish to blackish brown, basal flagellomere darker, densely microtomentose. Face mostly brown to grayish brown, darker dorsally, dorsum of hump brown, becoming grayer laterally in antennal fovea, lacking metallic reflections. Gena-to-eye ratio 0.38–0.48.

Thorax ( Figs. 24–26 ): Mesonotum mostly dark colored, brownish, darker along setal tracks, darker areas with considerable metallic reflections, shiny, but less so than mesofrons; scutellar disc mostly shiny, metallic bronzish, shiny area becoming diffused, gray toward periphery; postpronotum, notopleuron, and area just posterior of notopleuron gray to slightly tannish gray. Acrostichal setulae, except for posterior pair, small, sparse, and not organized into rows. Anepisternum brown to tan, becoming grayer ventrally; katepisternum gray. Wing: Veins and crossveins frequently darkened. Costal vein ratio 0.20–0.21; M 1 vein ratio 0.68–0.85. Femora and tibiae mostly gray, becoming darker, slightly blackish dorsally, toward apices; tarsi blackish brown dorsally, yellowish ventrally.

Abdomen ( Figs. 27–30 ): Tergites slightly two-toned, anterior 2/3 of each tergite dark green, metallic, ventral 1/3 grayish green. Male terminalia ( Figs. 27–30 ): Epandrium in posterior view ( Fig. 27 ) high, width about 2/3 height; surstyli in posterior view ( Fig. 27 ) with lateral margin shallowly but distinctly sinuous, apical extensions oriented laterally medial processes thickly developed basally, medial surface straight, lateral surface shallowly curved to acute apex; phallus in lateral view ( Fig. 28 ) longer than high, basal half roughly quadrate, apical half as a slender, parallel-sided, knife-like process, dorsal surface with a short, slender projection at midlength, thereafter apically with small U-shaped concavity, in ventral view ( Fig. 29 ) with apical 2/3 as a single, medial projection that gradually expanded from base to apex, apical surface tridentate with medial extension longer, triangular, base of apical section as 2 basolateral, digitiform projections with an obtuse point laterally, basal 1/3 of phallus with base as a band that is shallowly curved apicad laterally, thereafter as two band-like structures that connect with the apical 2/3 of the phallus; phallapodeme in lateral view ( Fig. 30 ) with keel only slightly shorter than height, extended margin shallowly rounded, ventral extension (to postgonite) nearly twice length as dorsal extension (to base of phallus), in ventral view ( Fig. 29 ) narrowly triangular, basal half nearly parallel sided, apical half flared to meet with basal band of phallus; postgonite+hypandrium in lateral view ( Fig. 30 ) somewhat rectangular, slightly expanded apically, apical margin shallowly sinuous, acutely pointed at ventroapical corner, in ventral view ( Fig. 29 ) with lateral margins rounded, apical 1/3 as a recurved extension, angulate medially as base, thereafter as a narrow extension, paralleling phallus.

Primary Type Material.— The lectotype female of Ephydra macquariensis Womersley , herein designated, is labeled “ TYPE [handwritten; circle; red]/Coll. 1670. S/a. 3/12/30 Macquarie I. B.A.N.Z.A. R.F Id. by H. Womersley [except for “Id. by H. Womersley’ ” handwritten; white]/ SAMA 29-5984 QR code box/ LECTOTYPE ♀ Ephydra macquariensis Womersley , designated by Mathis & Zatwarnicki red].” The lectotype female is double mounted (minute in a white rectangular block), is in good condition, and is deposited in the SAMA. Ten female paralectotypes ( SAMA 29-5985 – 29-5994 ), these also designated as paralectotypes herein, bear the same locality data as the lectotype .

Other Specimens Examined from Macquarie Island.— Aerial Cove (54°29.8′S, 158°56.2′E), 3 Mar 1961, K. C. Watson (4♂, 7♀; USNM) ; Bauer Bay (54°33.2′S, 158°52.6′E), 4 Jan 1961 K. C. Watson (1♂, 2♀; USNM) . Green Gorge (54°37.9′S, 158°53.9′E), 14 Feb 1961, K. C. Watson (3♀; USNM) ; Halfmoon Bay (54°29.9′S, 158°52.8′E), 8–19 Jan 1961, K. C. Watson (2♀; USNM) ; Langdon Point (54°31′S, 158°51.6′E), 19 Jan 1961, K. C. Watson (1♂, 1♀; USNM) ; Hasselborough Bay (54°29.6′S, 158°56.2′E), 5 Dec 1961, K. C. Watson (6♂, 7♀; USNM) .

Specimens Listed from Macquarie Island (these data taken from Wirth 1961: 971; all specimens collected by K. C. Watson in 1961): Plateau (54°29.9′S, 158°56.6′E), 8 Jan; Gadget Gully (54°30.5′S, 158°56.2′E), 26 Jan .

Type Locality.— Australasian / Oceanian: Macquarie Island; Station 81 (54°29.8′S, 158°56.2′E)

Distribution.—Australasian/Oceanian: Macquarie Island.

Remarks.—This species is distinguished from congeners from New Zealand, especially E. aquaria , E. assimilis , or E. thermarum , by the following combination of characters: facial protrusion or hump mostly unicolorous; mesonotum mostly shiny along setal tracks, metallic bronze, with gray area laterally; legs gray, tarsi, including the basitarsomeres, blackish brown dorsally, yellow ventrally; lateral surstylar processes relatively short, the lateral margins generally concave and sinuous. The apical extension is oriented slightly laterally and is blunt tipped.

Externally, E. macquariensis is very similar to E. aquaria , and we treat the former as a separate and valid species primarily based on the distinctive shape of structures of the male terminalia and the wide geographic disjunction (distance between Macquarie Islands and Wellington, New Zealand, is 1929 km).

The structures of the male hypopygium of this species are an interesting admixture of structures that externally demonstrate remarkable similarity to those of E. assimilis , especially the sinuous lateral margins of the surstyli and the proportionately large medial extension, which is thickened basally and is relatively long, compared to the length of the surstyli. The internal structures, on the other hand, are much more similar to those of E. aquaria , especially the projected keel of the phallapodeme (best seen in lateral views, Figs. 30 ), the apical, sword-like structure of the phallus in lateral view ( Fig. 30 ) and the rectangular-shaped postgonite-hypandrium complex. Even in dorsal views these structures are similar, though different in details. For example, the base of the phallus flares laterally as thumb-like, short, lateral projections, and the posterior projections of the postgonite are thin and slipper-like in both species.

Although Womersley (1937) first formally described this species, it had been reported seventeen years earlier by Tillyard (1920: 24–25) who provided an illustration of the larva and the crochets of an abdominal proleg. Tillyard further suggested that this species was a cranefly (family Tipulidae ) and proposed that (p. 25): “This larva and pupae may very probably belong to the genus Dicranomyia , or to some closely allied genus.” The pupa, which is a Nematoceran, may indeed represent a species of Dicranomyia Lamb or allied genus ( Tipulidae ). The larva, however, is a shore fly of the tribe Ephydrini and undoubtedly represents E. macquariensis , the only known species of that tribe from Macquarie Island.

Figures

FIGURES 24–26. Head and thorax of Ephydrella macquariensis (Womersley). 24. Head and thorax, latero-oblique, view. 25. Same, lateral view. 26. Same, dorsal view. Scale bar = 0.5 mm.

FIGURES 27–30. Male terminalia of Ephydrella macquariensis (Womersley; specimens from Macquarie Island. Aerial Cove, 3 Mar 1961, K. C. Watson). 27. External structures, posterior view. 28. Same, lateral view. 29. Internal structures, ventral view. 30. Same, lateral view. Scale bar = 0.1 mm.