First record of the genus Plynnon Deeleman-Reinhold, 2001 from China, with the description of a new species (Araneae, Phrurolithidae)

Abstract Background Plynnon Deeleman-Reinhold, 2001 is a small phrurolithid spider genus distributed in Southeast Asia, with three currently known species: P.longitarse Deeleman-Reinhold, 2001 and P.zborowskii Deeleman-Reinhold, 2001 from Borneo and P.jaegeri Deeleman-Reinhold, 2001 from Sumatra. New information Plynnonaduncum sp. n. (♂, ♀) from Yunnan Province, China is described, representing the northernmost record for the genus. Illustrations and morphological descriptions are provided.


Introduction
The spider family Phrurolithidae Banks, 1892 includes 304 extant and three fossil species in 20 genera (Dunlop et al. 2020, World Spider Catalog 2022. The genus Plynnon was established by Deeleman-Reinhold in 2001, based on the type species P. jaegeri Deeleman-Reinhold, 2001 and two other species. In Deeleman-Reinhold's original diagnosis, she made a detailed distinction between Plynnon and its similar genus Orthobula, which was then in the subfamily Phrurolithinae of Corinnidae, but has now been transferred to Trachelidae. Members of Plynnon are small to medium sized (2-5 mm), dark to reddish-brown spiders. Plynnon can be distinguished from other phrurolithid genera by the broad white band in the middle or distal half of tibia I, absence of spines on all the femora, absence of a tibial apophysis, conductor and median apophysis in the male palp, the special transverse copulatory ducts in the female vulva (Deeleman-Reinhold 2001), cheliceral anterior spines absent and the anterior metatarsi with only one pair of ventral spines (vs. at least two pairs of ventral spines in other phrurolithids).
Here, one new species of this genus is described from Yunnan Province, south-western China.

Materials and methods
All measurements are given in millimetres (mm). Leg measurements are shown as: total length (femur, patella, tibia, metatarsus, tarsus). Total length is the sum of the carapace and abdomen lengths. Epigynes were removed and cleared in a pancreatin solution (Álvarez-Padilla and Hormiga 2007), transferred to alcohol and temporarily mounted for illustration. All specimens are preserved in 75% alcohol and were examined, illustrated and measured with a Leica M205A stereomicroscope, equipped with an Abbe drawing device. Photographs were taken using a Leica M205A stereomicroscope, equipped with a DFC550 CCD camera. The distribution map was downloaded from China Map Press (www.chinamap.com) and edited in CorelDRAW® Graphics Suite 12. The specimens used in this study are deposited in the Museum of Hebei University, Baoding, China (MHBU).

Taxon treatment
Palp as illustrated ( Fig. 2 and Fig. 4A-C). Femur with a cup-shaped retrolateral distal boss; patellar and tibial apophyses absent. Tegulum pyriform, with an ovate subapical protrusion; sperm duct U-shaped and short, only present in apical half of tegulum. Embolus beak-shaped, with sharp tip pointed retrolaterally. Cymbium apically with a tuft of thick, flat setae around the apex of embolus.

Diagnosis
The new species is similar to Plynnon zborowskii in having a pyriform palpal tegulum and the long oval spermathecae that have similar position, but can be distinguished by: 1) embolus beak-shaped ( Fig. 2B and Fig. 4B)

Etymology
The specific name is a Latin adjective meaning "hooked". It refers to the front part of copulatory ducts curved as hook-shaped.

Discussion
In our opinion, the genus Plynnon is correctly assigned to Phrurolithidae rather than Trachelidae, considering the spination pattern in both sexes: the presence of pairs of strong ventral spines on the anterior tibiae and metatarsi and combination of the absence of any ventral spines or cusps on the anterior tarsi. By contrast, in Trachelidae, there are three conditions: 1) the anterior legs without any spines and cusps, such as Trachelas minor O. Pickard-Cambridge, 1872, the type species of the genus Trachelas L. Koch, 1866(Jin et al. 2017; 2) the anterior tibiae, metatarsi and tarsi all with pairs of strong ventral spines, such the genus Orthobula Simon, 1897 (Deeleman-Reinhold 2001); 3) the anterior tarsi with ventral cusps, at the same time, the anterior metatarsi and tibiae with cusps or spines, such as the genus Spinotrachelas Haddad, 2006(Haddad 2006) and Cetonana Strand, 1929(Jin et al. 2017b).