Baiyuerius rotulus (Liu, Li & Pham, 2010)

Wei, Mian, Zhu, Yang, Liu, Jie, Zhang, He & Liu, Fengjie, 2025, New species and new combinations of the spider genus Baiyuerius Zhao, B. Li & S. Q. Li, 2023 (Araneae, Agelenidae, Coelotinae), Zootaxa 5636 (3), pp. 401-442 : 427

Baiyuerius rotulus -species group

Diagnosis. Males of the species in this group can be identified by 1) lateral tibial apophysis and retrolateral apophysis sharp (fig. 1D in Hoang et al. 2023); 2) tegular sclerite Y-shaped (fig. 1C in Hoang et al. 2023); 3) conductor strongly sclerotized, process of dorsal margin of conductor with short basal stalk, and with two long branches, the retrolateral one curved and with distal part pointed upward (fig. 1B, C in Hoang et al. 2023). Females of species in rotulus -group can be identified by 1) epigynal teeth absent, epigynal plate large, length of epigynal pocket subequal to width ( Figs 23A , 25A ; fig. 2B in Hoang et al. 2023); 2) hood triangular ( Figs 23A , 25A ; fig. 2A in Hoang et al. 2023); 4) copulatory ducts long, without blind sacs ( Figs 23B , 25B ; fig. 2C in Hoang et al. 2023).

Notes. The long and sharp retrolateral and lateral tibial apophysis, as well the human-ear-shaped median apophysis in male palps, and the large epigynal plates and long copulatory ducts in females indicate that the rotulusgroup species strongly resemble those of the chongzu- group species. But the epigynal teeth are critical structures and may be correlated to functional aspects during copulation, which suggested that absence, presence, size, distance, position etc. are most likely more similar in closely related groups ( Wang & Jäger 2010). The absence of the epigynal teeth indicates that rotulus- group species should be distinguished from chongzu- group. The rotulus- group females lack the posterior epigynal sclerite (or with small and membranous one in B. rotulus ) and the blind sacs of the copulatory ducts, which are both present in the chongzu- group females. Moreover, the distributions of these two groups are hardly overlapped, rotulus- group species distribute in lower dimension area, while chongzu- group species distribute norther. Therefore, it is reasonable to divide these three species into a separate group.

Distribution. China (Yunnan Province), Vietnam (Vinh Phuc Province).

Species included. Three species are included in this group: Baiyuerius rotulus ( Liu, Li & Pham, 2010) and Baiyuerius shenyunxiaoi sp. nov. and Baiyuerius wenshanensis sp. nov.

Figures

FIGURE 23. Epigyne and internal genitalia of Baiyuerius shenyunxiaoi sp. nov. A epigyne, ventral view B internal genitalia, dorsal view. Abbreviations: A = atrium; CD = copulatory duct; CO = copulatory opening; FD = fertilization duct; H = hood; S = spermatheca; SE = swollen epigyne; SH = spermathecal head. Scale bar: 0.50 mm.

FIGURE 25. Epigyne and internal genitalia of Baiyuerius wenshanensis sp. nov. A epigyne, ventral view B internal genitalia, dorsal view.Abbreviations: A = atrium; AH = anterior hood; CD = copulatory duct; CO = copulatory opening; FD = fertilization duct; H = hood; S = spermatheca; SE = swollen epigyne. Scale bar: 0.50 mm.