Parahyadina bifurcata, 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 : 415-416

Parahyadina bifurcata , sp. nov.

( Figs. 17 , 19–22 , Map 4 )

Diagnosis. This species is distinguished from congeners by the following combination of characters: Adults. Small to moderately small shore flies, body length 1.85–2.20 mm.

Head ( Fig. 17 ): Lateroclinate fronto-orbital seta well developed, basal diameter comparable or only slightly reduced in comparison to basal diameters of vertical setae.

Thorax ( Fig. 17 ): 2 pairs of posterior dorsocentral setae, anterior seta shorter than posterior seta. Wing hyaline; costal section II about equal in length to costal section III; costal vein ratio 0.87–0.97; M vein ratio 0.23–0.25

Abdomen. Tergites 3–5 with ventrolateral margin shallowly rounded; male tergite 5 extended posteriorly in same plane as tergite 4. Male terminalia ( Figs. 19–22 ): Epandrium in posterior view ( Fig. 19 ) as an inverted, irregular U, surstyli oriented posteriorly, widest at ventral level of cerci, in lateral view ( Fig. 20 ) with dorsal portion of epandrium linear, shallowly concave on anterior and posterior margins, width of dorsal and ventral portions subequal; surstylar length (from level of fusion; Fig. 19 ) subequal to cercal height, angled very slightly posteriorly, with a medial, obtuse protrusion dorsally, thereafter ventrally tapered to narrowly rounded apex, apex bearing a single, short setula, also bearing 5 larger setulae in a vertical line along anterior margin at midlength, length of these setulae twice that of apical setula; cercus in posterior view ( Fig. 19 ) narrowly obovate, shallowly curved with narrowed dorsal apex nearly abutting that of other cercus, in lateral view ( Fig. 20 ) height almost twice width with anterior margin somewhat straight, posterior margin regularly but unevenly arched; aedeagus heavily sclerotized, in lateral view ( Fig. 22 ) rectangularly tubular, longer than wide, with base shallowly bifurcate with asymmetric, short arms, thereafter apically as straight, gradually tapered to moderately rounded apex, in ventral view ( Fig. 21 ) as a wide, squat, irregular drop with narrowed apical portion as a step before short apex, basally with shallow, medial V- shaped notch; phallapodeme in lateral view ( Fig. 22 ) irregularly rectangular, elongate, keel elongate, narrowly spool shaped, base with blunt, digitiform, elongate process extended to aedeagal base, opposite angle moderately acutely angulate, in ventral view ( Fig. 21 ) I-shaped with both apical and basal margins expanded; gonite and hypandrium broadly fused, in lateral view ( Fig. 22 ) robustly L-shaped, gonal portion shorter but more robust, bearing a shallowly triangular, sub-basal projection and an apical, digitiform projection, hypandrial portion much longer than wide, narrowly rectangular, lateral margins irregular, in ventral view ( Fig. 21 ) wider than long, basal portion (hypandrium) band-like, shallowly curved, lateral extensions (gonite) longer than wide, irregular, with apical portion bifurcate, medial prong oriented medially, digitiform, lateral prong narrowly triangular, shorter than medial prong.

Type Specimen. The holotype male is labeled “ NEW ZEALAND. S. Isl. FD: MonowaiRiv. 45°46.7’S 167°35.7’E; 171 m, 17–18 Jan. 2004, W. N. Mathis/ USNM ENT 00028123 [plastic bar code label]/ HOLOTYPE ♂ Parahyadina bifurcata Mathis & Zatwarnicki NZAC [red].” The holotype is double mounted (minuten in block of plastic elastomer), is in good condition (abdomen removed and dissected), and is deposited in NZAC.

Type locality. New Zealand. South Island. FD: Monowai (45°46.5’S, 167°37.0’E; 120 m) .

Other specimens examined. SOUTH ISLAND. KA: Hapuku Stream (42°13’S, 173°45.3’E; 420 m), 8 Jan 2004, W. N. Mathis (1♂; USNM).

Distribution ( Map 4 ). Australasian/Oceanian: New Zealand. South Island (FD, KA).

Etymology. The species epithet, bifurcata , is of Latin derivation and refers to the deeply bifurcate aedeagal base in lateral view.

Remarks. Although similar to P. bulla and P. lacustris , this species is distinguished by the greater number of setulae (5–6) on the surstylus at midheight. In addition, the aedeagus in lateral view is shoe-like with tapered and narrow “toe,” and the base of the aedeagus is relatively deeply bifurcate.

Figures

MAP 4. Parahyadina bifurcata.

FIGURES 17–18. Antero-oblique view of head and thorax (Scale bar = 0.2 mm). 17. Parahyadina bifurcata sp. nov. (male; New Zealand. South Island. FD: Monowai River). 18. Parahyadina bulla sp. nov. (male; New Zealand. Chatham Island. Tennants Lake).

FIGURES 19–22. Parahyadina bifurcata sp. nov. (male; New Zealand. South Island. FD: Monowai River). 19. Epandrium, cerci, and surstyli, posterior view. 20. Same, lateral view. 21. Internal structures of male terminalia, ventral view. 22. Same, lateral view (scale bar = 0.1 mm).