Balticopteryx Chen, 2018

Chen, Zhi-Teng, 2018, First record of subfamily Brachypterainae (Plecoptera: Taeniopterygidae) in Baltic amber: a new genus and species, Zootaxa 4527 (4), pp. 569-574 : 570

Genus Balticopteryx Chen , gen. nov.

Type species. Balticopteryx dui gen. et sp. nov., by monotypy.

Diagnosis. Diagnostic characters of the new genus Balticopteryx include: 1) body size extremely small, about 6.0 mm in length; 2) biocellate, each ocellus small and distant to each other; extremely long antennae, with about 50 segments; 3) wings without characteristic patterns, veins simple; RP, M and CuA of forewing each with two branches; only a single h vein presents in the costal area; 4) coxal gills absent; three tarsal segments equal in length; 5) sternum 8 mostly membranous, posteriorly with a small genital opening, anterior of the opening forming a sclerite; 6) postgenital plate elongated and pointed distally, exceeding part of the paraprocts; 7) cerci sixsegmented, apical segment unmodified.

The new genus is readily assigned to the family Taeniopterygidae because of the clear presence of three tarsal segments equal in length ( Stewart & Stark 2008, Teslenko & Zhiltzova 2009, Chen & Du 2018). Based on the wellproduced postgenital plate and the absence of coxal gills, this genus belongs to the subfamily Brachypterainae ( Ricker & Ross 1975) . In Taeniopterygidae , only the genus Kyphopteryx Kimmins, 1947 lacks the anterior ocellus; only in Doddsia Needham & Claassen, 1925 and Mesyatsia Ricker & Ross, 1975 , the anterior ocellus tends to be smaller than normal ( Ricker & Ross 1975, Zhiltzova & Zwick 1993). The complete absence of anterior ocellus in Balticopteryx has excluded its recognition as other taeniopterygid genera except for Kyphopteryx . Apart from the number of ocelli, other comparisons are made between Balticopteryx and the three above mentioned genera, Kyphopteryx , Doddsia and Mesyatsia .

In the three species of Kyphopteryx , the hind wing is exceptionally triangular, which is in normal shape in Balticopteryx (see figs. 623, 625 in Teslenko & Zhiltzova 2009 and fig. 1B in Kimmins 1946); RP has three branches in both wings, which has only two in Balticopteryx; wings have more irregular crossveins especially in subapical section, while the wing venation is simple in Balticopteryx; the 8th sternum of female is completely or partially sclerotized with a notch on posterior margin (see figs. 622, 624 in Teslenko & Zhiltzova 2009 and fig. 3G in Kimmins 1 946), which is mostly membranous in Balticopteryx with a small posterior genital opening. In the only species of the Nearctic Doddsia , Doddsia occidentalis ( Banks, 1900) , there are additional costal crossveins and more branches of RP and CuA in forewing (see fig. 3 of plate 33 in Needham & Claassen 1925); the sternum 8 is cleft at posterior half and the postgenital plate is beyond the abdominal tip (see fig. 1 of plate 46 in Needham & Claassen 1925), but in Balticopteryx, the sternum 8 is almost complete, and the postgenital plate is much shorter, only covering part of the paraprocts. In Mesyatsia , there are two to four costal crossveins including the humeral crossvein in the forewing ( Ricker & Ross 1975, Teslenko & Zhiltzova 1992, 2009), but there is only one in Balticopteryx. In addition, the female of Balticopteryx exhibits a much smaller body size of about 6 mm. In the other three genera, body size is generally over 10 mm in females.

Etymology. The genus name Balticopteryx refers to the holotype collection locality, Baltic.