Curiosyntexis magadanicus Kopylov, 2019

Kopylov, Dmitry S., 2019, New anaxyelids (Hymenoptera: Anaxyelidae) from the Cretaceous of Asia, Zootaxa 4603 (2), pp. 341-353 : 349-350

Curiosyntexis magadanicus Kopylov , sp. nov.

( Fig. 2 E–H)

Etymology. The species name is derived from Magadan Region.

Material. Holotype PIN 3901 /19, part and counterpart imprint in tuffaceous mudstone. Imago, female. Head damaged, thorax poorly preserved excluding well-preserved mesonotum, abdomen well-preserved; antennae dissected, legs poorly preserved; fore wings partly destructed, but combining left and right wings allows to reconstruct fore wing venation, hind wings almost not preserved excluding R and a short part of Rs. Obeshchayushchiy; Russia, Magadan Region; Upper Cretaceous , Cenomanian, Ola Formation.

Description. Body uniform dark; fore wing with C, R and veins surrounding pterostigma dark, other veins paler, wing membrane without color pattern. Antennae with more than 12 antennomeres, antennomeres gradually decreasing in length and width from base towards antennal tip; the last antennomere rounded apically. Mesonotum sculptured with fine slightly transverse teeth; scutellum pointed forwards; the ratio of lengths of prescutum/longitudinal sulcus between the prescutum and scutellum/scutellum is 1.3/1.0/2.2. Fore wing with pterostigma 3.2 × as long as wide, veins enclosing pterostigma not wider than C or R, 2r-rs joining pterostigma at its midlength; 1-Rs 2.3 × as long as 1-M; 1-Rs joining Rs+M with almost no bent; Rs+M 0.8 × as long as 1-Rs; 3-Rs 1.7 × as long as 2-Rs and 4.7 × as long as 3+4Rs; 2+3-M 1.8 × as long as 4-M; distance between bases of 1r-rs and of pterostigma (estimated 1r-rs length) 2.1 × as long as 2r-rs; 2r-rs slightly reclined, 0.5 × as long as pterostigma width; cell 2+3rm 1.5 × as long as wide; cell 1mcu 1.6 × as long as wide; 1-Cu 0.6 × as long as 2-Cu; 1m-cu arched, proclined; 4-Cu 0.4 × as long as 3-Cu, meeting 3-Cu at right angle; 2m-cu strongly proclined, arched basad. Hind wing with only R and short stub of Rs tubular. Abdomen with tergites 1–6 almost of same width and length, tergites 7–9 1.6–2.0 × longer; ovipositor full length equals 0.87 × fore wing length, not protruding beyond apex of abdomen.

Measurements: body length 11.7 mm; head length 1.3 mm, thorax length 2.9 mm, abdomen length 7.2 mm, ovipositor length 4.8 mm; fore wing length 4.2 mm (preserved), 5.5 mm (estimated), width 2.4 mm.

Remarks. Curiosyntexis magadanicus is the only anaxyelid species discovered from the Late Cretaceous and the last in fossil record. It belongs to subfamily Syntexinae , the most abundant in Cretaceous and the only living nowadays.

The venation of this species is strongly apomorphic, and even more specialized than in recent Syntexis libocedrii . The venation of basal half of fore wing (‘before pterostigma’) is quite usual for syntexines. The only notable character here is partly lost 1r-rs vein. The previously known Cretaceous syntexines ( Eosyntexis , Cretosyntexis ) have this vein lost completely, while newly reported genera (Parasyntexis, Dolichosyntexis) have it fully developed. In Syntexis this character varies from fully developed to partly developed, like in Curiosyntexis. Widely desclerotized pterostigma of Curiosyntexis is unique within Cretaceous representatives of the subfamily, but characteristic for recent Syntexis . The apical half of forewing is deeply transformed. Transverse veins 3r-m and 2m-cu strongly displaced basad, 3r-m widely desclerotized. Tubular veins not developed beyond line connecting apices of pterostigma and 1A: even R, usually very strong in anaxyelids, is lost. Nevertheless, this species does not seem to be brachypterous. The veins in apical third of forewing were apparently replaced by a field of longitudinal folds like in some Siricidae (Tremex) or some Vespina ( Tiphiidae : Brachycistidinae ; Mutillidae ; Bradynobaenidae etc.). Hind wing venation is also deeply reduced. The only tubular veins are R and the base of Rs.

The fine teeth covering the surface of the mesonotum is evidently an adaptation to wood-boring ( Vilhelmsen & Turrisi 2011). It corresponds to the life-style known for recent Anaxyelidae . The transverse sculpture on mesonotum (teeth or rugae) is also known for recent Syntexis libocedrii , fossil Cretosyntexis montsecensis and Eosyntexis sp. (not described specimens from Burmese amber, pers. data). Ortega-Blanco with coauthors (2008) suppose that the sculptured mesonotum is characteristic for the whole subfamily Syntexinae , although this character is not known for the majority of fossil species due to the poor state of preservation.

Figures

FIGURE 2. A–B—Parasyntexis khasurtensis gen. et sp. nov., holotype PIN 5340/2178, Khasurty, Russia, Lower Cretaceous: A—interpretation (showing names of the veins used in this paper), B—part; C–D—Dolichosyntexis transbaikalicus gen. et sp. nov., holotype PIN 3064/1941, Baissa, Russia, Lower Cretaceous: C—interpretation, D—part; E–H—Curiosyntexis magadanicus gen. et sp. nov., holotype PIN 3901/19, Obeshchayushchiy, Russia, Upper Cretaceous: E—interpretation, F—reconstruction of fore wing obtained by the merging of preserved parts of left and right wings, G—part, H—counterpart. Scale bars 5 mm.