Isosetosa minxianensis Xu, Zhang & Jiang, 1989

Chen, Juanjuan, Zhang, Junqian & Xie, Zhicai, 2025, List of species records of enchytraeids (Enchytraeidae, Clitellata, Annelida) in China, Zootaxa 5566 (1), pp. 61-96 : 87

Isosetosa minxianensis Xu, Zhang & Jiang, 1989 [nomen dubium] (T) (endemic to China)

Isosetosa minxianensis Xu, Zhang & Jiang, 1989 .

Type locality. Minxian agricultural technology extension station, Dingxi city, Gansu Province.

Distribution and habitat. Only known from type locality. Terrestrial.

Distribution in China. Gansu Province.

Remarks. Xu et al. (1989) established Isosetosa based on specimens collected from Gansu Province, Minxian. In the original description, Isosetosa differs from Fridericia in equally sized chaetae (4 per bundle, not fan-shaped with inner chaetae shorter than outer), absent dorsal pores and free spermathecae. All traits mentioned can be found in Fridericia species as well ( Schmelz 2003; Schmelz & Collado 2010). For example, almost equal-sized chaetae in bundles of 4 are present in F. isseli , free spermathecae are present in F. reducata ( Schmelz, 2003) , and dorsal pores may be absent in Fridericia maculata ( Schmelz & Collado 2010) .

Schmelz (2003) summarized the useful morphological characters from original description as follows: Length 5.5–9.0 mm, diameter 0.4–0.6 mm (fix). 30–41 segments. Four chaetae in lateral and ventral bundles. No dorsal pores. Cuticle thin. Brain in III (?). Oesophageal appendages present. Chylus cells present, in preclitellar or clitellar segments. Origin of dorsal blood vessel in postclitellar segment. Clitellum well-developed, cells higher than wide; in 1/2XI–XIII, covering 2.5 segment (?). Spermathecae without diverticula, not connected with oesophagus.

We were unable to obtain more information on this genus and species, which has not been recorded again after the original description. We did not search for the type material, and several attempts in Gansu province failed to find specimens that strictly match the original description. Pending a redescription, we leave Isosetosa minxianensis as nomen dubium, as well as Isosetosa .