Revision of the Shore-fly Genera Parahyadina Tonnoir and Malloch and New Zealand Hyadina Haliday (Diptera: Ephydridae) Author Mathis, Wayne N. Author Zatwarnicki, Tadeusz text Zootaxa 2019 2019-06-26 4623 3 401 440 journal article 26379 10.11646/zootaxa.4623.3.1 e08d625a-f512-45c8-9cd2-a1069798ddab 1175-5326 3258532 6C8F0D4B-1830-4B87-ACA4-824C356FDA91 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 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). 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. MAP 4. Parahyadina bifurcata . 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.