Siberiopelta bashkuevi Sinitshenkova & Yan, 2024

Sinitshenkova, Nina & Yan, Evgeny, 2024, The most ancient roachfly (Insecta: Plecoptera, Peltoperlidae) from the Lower Cretaceous of the West Transbaikalia, Russia, Zootaxa 5523 (2), pp. 284-290 : 285-288

Siberiopelta bashkuevi Sinitshenkova & Yan , sp. nov.

urn:lsid:zoobank.org:pub:E15C766C-5E89-47B1-A70A-E68C66373C71

(Figs. II–V)

Etymology. The new species is named in honor of the paleoentomologist Alexey Bashkuev, who collected the material during the field trip in 2019

Type material. Holotype No 5340/4159 part and counterpart of complete nymph, paratypes No 5340/4166 part and counterpart of nymph without head, No 5340/4158 part and counterpart of nymph without abdominal apex. Borissiak Paleontological Institute , Russian Academy of Sciences , Moscow. The location of Khasurty , 10 km south of the village. Tsakir (50 ° N, 103 ° E) in the Zakamensky district on the middle course of the Khasurty River in Buryatia , Western Transbaikalia, Russia.

Horizon and locality. The Formation is not designated. Lower Cretaceous, Neocomian in old sense ( Kopylov et al., 2020).

Diagnosis. As for the genus.

Description. Dimensions in mm. Body length of holotype 5340/4159—8.1, the length of the cerci—almost 1.5. Preserved body length of the paratype 5340/4158—9.5, paratype 5340/4166—9.5, its estimated total body length is about 12, the length of the cerci 2.0.

On holotype 5340/4159, where an almost intact nymph without antennae is preserved, the head length is 125% of the pronotum length, the eyes are located on the sides of the head. Width of the head is 52% of the pronotal width. Pronotum with slightly concave anterior and convex posterior margins; rounded lateral corners and slightly convex lateral margins. Mesothorax and metathorax with very short, widely rounded wing pads. The abdomen is 1.6 times longer than the thoracic region, which formed with short and wide segments. The forelegs are the shortest, the profemoral length is 1.4 times the length of the pronotum. The hind legs are the longest, the hind femur length is almost twice the length of the metathorax. The abdomen length is slightly more than 1.5 times its maximum width; the last abdominal segment has a wide rounded apex. Cerci consisting of short segments, at least 6, their length does not exceed the width of the last abdominal segment. The entire body is covered with dense setation.

On paratype 5340/4158, the head with fragments of antennae, the thoracic region with legs, and seven abdominal segments are preserved. The structural features of the head, pronotum and legs coincide with those of the holotype, but in contrast, this specimen preserves fragments of antennae, which are almost equal in length to the length of the thorax. The antennae consist of short segments, the length of which is slightly greater than their width. This paratype is larger than the holotype, its wing pads are longer, probably it represents the remnant of an older nymph. Setation as on holotype.

On paratype 5340/4166, the abdomen with the cerci, a fragment of the metathorax, and the hind legs with the tarsus are well preserved. On the hind femora there are clearly visible a notch into which the tibia fits at rest. The tibia of the hind leg is almost twice as long as the tarsus, which is twice as long as the double claw. The first two tarsal segments together are half as long as the third one. The length of the abdomen exceeds its width by 1.8 times. On the cerci, the first segment is slightly larger than the others, their length is slightly greater than the width of the last abdominal segment; 7–8 segments can be distinguished. Setation as on holotype.

Remarks. The nymphs on the prints look unusually very dark, they were probably dark colored during life.