Parahyadina irwini, Mathis & Zatwarnicki, 2019

Mathis, Wayne N. & Zatwarnicki, Tadeusz, 2019, Revision of the Shore-fly Genera Parahyadina Tonnoir and Malloch and New Zealand Hyadina Haliday (Diptera: Ephydridae), Zootaxa 4623 (3), pp. 401-440 : 429-432

Parahyadina irwini , sp. nov.

( Figs. 43 , 45–48 , Map 9 )

Diagnosis. This species is distinguished from congeners by the following combination of characters: Adults. Small shore flies, body length 1.35–1.85 mm.

Head ( Fig. 43 ): Lateroclinate fronto-orbital seta well developed, basal diameter comparable or only slightly reduced in comparison to basal diameters of vertical setae.

Thorax ( Fig. 43 ): Postsutural scutum without distinct, longitudinal vittae between acrostichal setae and dorsocentral setae. Wing hyaline; costal vein ratio 1.10–1.19; M vein ratio 0.23–0.38.

Abdomen. Tergites 3–5 with ventrolateral margin shallowly rounded; male sternite 4 weakly sclerotized, as 2 relatively approximate, lateral, longitudinal bars; male tergite 5 extended posteriorly in same plane as tergite 4; male sternite 5 Y-shaped, arms flared anterolaterally, moderately well developed. Male terminalia ( Figs. 45–48 ): Epandrium in posterior view ( Fig. 45 ) broadly oval with ventromedial projections tapered to narrowly rounded apex, bearing 4 setulae near midlength and a prominent apical setulae, in lateral view ( Fig. 46 ) with dorsal 2/3 narrow, linear, more or less parallel sided; surstylar length (from rounded, medial bump) about ½ height of cercus, angled slightly posteromedially, in lateral view ( Fig. 46 ) with a medial, short, hook-like protrusion, tapered from wider base to narrowly rounded apex, apex bearing a single, short seta, also bearing 4 setulae in a vertical line along anterior margin at midlength; cercus in posterior view ( Fig. 45 ) irregularly obovate, tapered to point dorsally, ventral margin broadly rounded, generally covered with small setulae, in lateral view ( Fig. 46 ) height almost twice width with anterior margin somewhat straight, posterior margin irregularly arched; aedeagus heavily sclerotized, in lateral view ( Fig. 48 ) tubular, elongate, with 2 basal prongs, dorsal protrusion about 3 times length of basal one, apically as an abruptly narrowed, acutely pointed projection, length slightly less than aedeagal width at midlength, in ventral view ( Fig. 47 ) about as wide as long, base broadly rounded, apical third narrowed, short, parallel sided with a short, medial projection; phallapodeme in lateral view ( Fig. 48 ) irregularly triangular with 2 moderately narrowed angles and truncate, wide, keel as third angle, in ventral view ( Fig. 47 ) narrowly hour-glass shaped, base narrowly Y-shaped with short arms, apex tapered to point, widest subapically; gonite and hypandrium broadly fused, in lateral view ( Fig. 48 ) robustly L-shaped, gonal portion bearing a digitiform, shallowly curved projection, hypandrial portion longer than wide, narrowly rectangular, in ventral view ( Fig. 47 ) generally irregularly rectangular, convexly truncate basally, becoming slightly wider posteriorly, posterior margin abruptly narrowed as digitiform, medially curved projections.

Type Specimen. The holotype male is labeled “ NEW ZEALAND. S. ISL. NN: Flora Saddle (41°11.4’S, 172°44.2’E), 12Feb 1998 [,] Wayne N. Mathis/ USNM ENT 00085386 [plastic bar code label]/ HOLOTYPE ♂ Parahyadina irwini Mathis & Zatwarnicki NZAC [red].” The holotype is double mounted (minuten in block of plastic elastomer), is in excellent condition, and is deposited in NZAC. Seven paratypes (4♂, 3♀; NZAC, USNM) bears the same label data as the holotype except for one male for which V. Hollmann was the collector.

Type locality. New Zealand. South Island. NN: Flora Saddle (41°11.4’S, 172°44.2’E) .

Other specimens examined. NORTH ISLAND. ND: Whananaki (7 km SW; freshwater creek; 35°32.9’S, 174°24.6’E), 6 Oct 2002, D. and W. N. Mathis (1♂; USNM).

SOUTH ISLAND . CO: Danseys Pass (1.2 km SW; 44°57.2’S, 170°22.0’E; 856 m), 11 Jan 2004, W. N. Mathis (1♂, 2♀; USNM) ; Danseys Pass (2.2 km NE; 44°56.9’S, 170°24.2’E; 586 m), 11 Jan 2004, W. N. Mathis (2♂, 2♀; USNM) . FD: Borland Saddle (22 km W Monowai; 45°44.8’S, 167°23.2’E; 945–988 m); 18 Jan 2004, W. N. Mathis (2♂, 2♀; USNM); Lake Monowai (45°48.7’S, 167°31.3’E; 225 m); 17–20 Jan 2004, W. N. Mathis (1♂; USNM); Monowai River (45°46.7’S, 167°35.7’E; 171 m); 17–18 Jan 2004, W. N. Mathis (4♂, 3♀; USNM) . MC: Acheron River (43°19.7’S, 171°40.5’E; 772 m), 10 Jan 2004, W. N. Mathis (3♂, 3♀; USNM); Lake Pearson (43°05.6’S, 171°46.8’E; 612 m); 3 Feb 2004, W. N. Mathis (4♂, 3♀; USNM) . NN: Graham Valley (41°12.1’S, 172°50.8’E), 12 Feb 1998, W. N. Mathis (1♂, 1♀; USNM) . SL: Orepuki (46°16.9’S, 167°44.3’E), 8 Feb 1976, L. L. Deitz (1♀; NZAC) .

Distribution ( Map 9 ). Australasian/Oceanian: New Zealand. North Island (ND), South Island (CO, FD, MC, NN, SL).

Etymology. The species epithet, irwini , is a Latinized genitive patronym to honor the contributions of Anthony G. Irwin to our study of shore flies ( Diptera : Ephydridae ), especially his editing skills and knowledge of the literature.

Remarks. Externally, this species is very similar to P. edmistoni , P. latistylis , and P. debilis but is distinguished from these by the following combination of characters: Male tergites three through five with ventrolateral margins shallowly and bluntly rounded, not acutely developed, as in P. edmistoni ; and male tergite five extends posteriorly in the same plane as tergite four. Structures of the male terminalia distinguish this species, especially the moderately short and thin surstylus and the robust and L-shaped gonite ( Fig. 48 ). The length of the gonite in lateral view ( Fig. 48 ) is about twice its basal width, the apex is irregularly and bluntly rounded, and there is a lateral, digitiform prominence.

Figures

MAP 9. Parahyadina irwini.

FIGURES 43–44. Antero-oblique view of head and thorax (Scale bar = 0.2 mm). 43. Parahyadina irwini sp. nov. (female; New Zealand. South Island. NN: Flora Saddle). 44. Parahyadina lacustris Tonnoir & Malloch (male; New Zealand. North ISLAND. ND: Whangaroa).

FIGURES 45–48. Parahyadina irwini sp. nov. (male; New Zealand. South Island. NN: Flora Saddle). 45. Epandrium, cerci, and surstyli, posterior view. 46. Same, lateral view. 47. Internal structures of male terminalia, ventral view. 48. Same, lateral view (scale bar = 0.1 mm).