Idopterum Hampson, 1894

Huang, Si-Yao, Volynkin, Anton V., Wang, Min & Fan, Xiao-Ling, 2020, A new species of the subgenus Idopterum Hampson, 1894 of the genus Ammatho Walker, 1855 from China (Lepidoptera: Erebidae: Arctiinae: Lithosiini), with redefinition of the subgenus Idopterum, Zootaxa 4885 (2), pp. 271-276 : 272-273

Subgenus Idopterum Hampson, 1894

(Type species: Idopterum ovale Hampson, 1894 , by the original designation).

Idopterum Hampson, 1894 : The Fauna of British India, including Ceylon and Burma 2: 103, fig. 69

Ammatho (Idopterum) Hampson : Volynkin et al. 2019: 20, figs 11, 12, 109, 165.

Diagnosis. Excluding the unexamined A. (I.) admirabilis and A. (I.) novaepommeraniae , which might probably do not belong to this subgenus (see below), members of Idopterum have whitish or yellowish ground color on forewing with particular dark shades of different shapes. The male and female genitalia of Idopterum are similar to the ground plan of Ammatho (Striatella) . However, the male genitalia of Idopterum are characterized by the juxta with smooth or dentate medial bulge and lateral slender process, extremely long and medially curved distal costal process and the aedeagus vesica bears large cornuti field at the junction of aedeagus and vesica.

Remarks. 1. Volynkin et al. (2019) stated that beside the unique wing pattern mentioned above, the genitalia ground plan of Idopterum of both sexes are similar to those of the subgenus Striatella of the genus Ammatho , but in Idopterum the distal costal process is extremely long, and the juxta has swollen and shortly dentate lateral lobes, and the latter feature is unique within the generic complex. With the discovery of I. wuchunshengi sp. nov., the feature of the juxta should be corrected as in the new species the lateral slender process of juxta is smooth and not dentate. Apart from the autapomorphies in distal costal process and the juxta, we found that the large cornuti field presenting at the junction of aedeagus and vesica can also well recognize Idopterum among the genus Ammatho and the whole Asura / Miltochrista generic complex, so we regard this feature as a new autapomorphies of Idopterum . 2. According to the original description of Schaus (1922), A. (I.) admirabilis is “Fore wings maize yellow, a black line on base of costa, a subbasal black point in cell, an antemedial black line inbent and straight to inner margin; a black line from antemedial in cell outbent to inner margin close to postmedial…a black point at end of cell; postmedial line inbent on costa to above discocellular spot…”, which means this species probably has a “miltochristoid” pattern commonly found across the Asura / Miltochrista generic complex, and does not fit in the forewing pattern ground plan of Ammatho (Idopterum) . It is highly possible that A. (I.) admirabilis is not a true member of Ammatho (Idopterum) . Meanwhile, things are similar in A. (I.) novaepommeraniae , whose description was presented only in Pagenstecher (1900) but without giving a formal scientific name for it. Pagenstecher (1900) stated that A. (I.) novaepommeraniae is something grayish white with a discal spot and a wavy medial line, and according to this statement A. (I.) novaepommeraniae does not fit in the forewing pattern ground plan of Ammatho (Idopterum) . It is highly possible that A. (I.) novaepommeraniae is also not a true member of Ammatho (Idopterum) . Anyway, until the holotype of admirabilis (housed in the United States National Museum, Washington, USA) is examined, and the holotype of novaepommeraniae is found (the location is currently unknown) or the neotype for this taxon is designated (if the holotype is not found), the issue of the generic placement of the two species cannot be resolved.

Distribution. Species of the subgenus are known from mainland China, Indochina, Java ( A. (I.) admirabilis ) and Bismarck Archipelago ( A. (I.) novaepommeraniae ).