Hyadinini Phillips

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 : 403

Tribe Hyadinini Phillips et alia

Hydrinini Cresson 1944: 175. Type genus: Hydrina of authors, not Robineau-Desvoidy 1830 (= Philygria Stenhammar 1844 ), unavailable, based on a junior homonym.

Hyadinini Phillips et alia in Cresson 1949: 251. Type genus: Hyadina Haliday in Curtis 1837 .— Mathis and Zatwarnicki 1995: 200–214 [world catalog].— Hollmann-Schirrmacher 1998: 29, 45–56 [discussion].— Zatwarnicki & Ryczko 2014: 495– 515 [phylogenetic analysis and revision at generic level].

Philygriini [nomen nudum].— Wirth & Stone 1956: 469.— Cogan 1984: 149 [Palearctic catalog].

Philygriini Lizarralde de Grosso 1989: 51. Type genus: Philygria Stenhammar 1844 .— Mathis & Zatwarnicki 1995: 190–200 [world catalog].— Hollmann-Schirrmacher 1998: 50 [synonymy with Hyadinini ].

Diagnosis. The tribe Hyadinini is similar to Ilytheini but is distinguished by the following combination of characters: aristal hairs tending to be reduced (sometimes secondarily moderately well developed); acrostichal setae reduced, prescutellar pair lacking; dorsocentral setae frequently reduced in size and/or number (1+2, 0+2, or sutural+1); subepandrial plate fused with gonite dorsally, forming a rounded projection, sometimes joined medially over aedeagus to form a gonal arch (= subepandrial plate); gonites and hypandrium usually fused; gonite produced posteriorly as a long triangular to almost parallel sided projection, with apex variously modified.

Discussion. The monophyly of the tribe Hyadinini is established by the following synapomorphies ( Zatwarnicki 1992: 76; Hollmann-Schirrmacher 1998: 50): (1) reduction of scutellar/prescutellar acrostichal setae; (2) fusion of gonite with hypandrium; (3) reduction of dorsocentral setae; (4) lack of long branches on the arista; and (5) ventral elongation of the epandrium.

Only three described genera of the tribe Hyadinini occur on New Zealand, and two are revised in this paper. One, Parahyadina , is apparently endemic to these islands. The three genera can be identified by the key that follows. Edmiston & Mathis (2007) revised the three New Zealand species of Nostima , and herein, we treat the New Zealand species of Hyadina and Parahyadina . The New Zealand species of “ Hyadina ” will be treated in a forthcoming paper.

The New Zealand fauna of “ Hyadina ” and Parahyadina are anomalous within Hyadinini . The two New Zealand species of “ Hyadina ,” H. irrorata Tonnoir & Malloch and H. obscurifrons Tonnoir & Malloch , for example, are unlike more typical congeners from elsewhere in the world, notably by their large size and shape of the head, especially the comparatively high gena (Zatwarnicki & Mathis 2019).

Although Tonnoir & Malloch (1926) described Parahyadina as a separate genus, based on the generally welldeveloped, lateroclinate fronto-orbital seta, the included species are more similar to species of Hyadina from elsewhere in the world, including H. pullipes Cresson (1930) from Australia, than are the two named indigenous species of “ Hyadina .” Moreover, two of the new species that we describe herein, P. breva and P. edmistoni , often have a reduced though evident, lateroclinate fronto-orbital seta, unlike other congeners. Thus, the New Zealand fauna of Hyadinini is structurally diverse, which is undoubtedly a reflection of their varied evolution and phylogeny, as well as biogeography.