﻿First record of the genus Touranella Attems, 1937 (Diplopoda, Polydesmida, Paradoxosomatidae) from Laos, with a description of a new species

﻿Abstract The paradoxosomatid genus Touranella Attems, 1937 is recorded from Laos for the first time, with a new species, Touranellachampasaksp. nov., described here. The taxonomy of the genus is discussed, an identification key is provided, and the current distribution of all species is mapped.


Introduction
The genus Touranella Attems, 1937 was established for a single species, Touranella gracilis Attems, 1937. Attems (1937 distinguished this genus from other paradoxosomatids recorded in Vietnam at that time by the following features: gonopod femorite strongly reduced or completely absent, and solenomere (= Rinnenast) arising from the prefemorite. No other records had been reported until Golovatch (1994: 186) described the second species of the genus, Touranella himalayaensis Golovatch, 1994, from Nepal. The type locality of T. himalayaensis lies approximately 2,500 km north of Vietnam, indicating a significant biogeographical gap among species in the same genus. Six additional species of Touranella were described between 2009-2018, five from Vietnam and one from Nepal. To date, eight Touranella species have been described (Sierwald and Spelda 2021), which are listed below: 1. Touranella cattiensis Golovatch & Semenyuk, 2010 from Cat Tien National Park, Dong Nai, Vietnam. 2. Touranella gracilis Attems, 1937 from Da Nang, Vietnam. 3. Touranella himalayaensis Golovatch, 1994 from Panchthar, Nepal. 4. Touranella hirsuta Golovatch, 2009 from Bi Doup-Nui Ba National Park, Lam Dong, Vietnam.
5. Touranella moniliformis Golovatch & Semenyuk, 2018 from Cat Tien National Park, Dong Nai, Vietnam. 6. Touranella peculiaris Golovatch, 2009  This work reports the first record of Touranella in Laos, with a description of a new species. With this discovery, the geographical gap in the distribution of this genus is slightly narrowed (Fig. 1).

Material and methods
Examined material was collected by M. Thayer and her colleagues during their field expedition to Laos in 2008 and is currently housed in the Field Museum of Natural History (FMNH).
The specimen was examined under a Leica M205 microscope. Line drawings were made using a camera lucida attached to the Leica M205 microscope. Colour images were taken using the Nikon 5100 imaging system with varying lens sizes under normal and ultraviolet (UV) light. Images were photographed in different layers and stacked using Helicon Focus v. 6.0, then grouped into plates in Photoshop v. 6.0. A gonopod was dissected for morphological observation and mounted on an aluminum stub, coated with gold for SEM imaging. SEM images were taken using a Leo Scanning Electron Microscope (Carl Zeiss SMT, Peabody, MA) at FMNH. A distribution map was created using Google Map. The new species can be recognized by a submoniliform body; poorly developed paraterga; sparsely setose metaterga; the presence of a highly elevated, setose, trapeziform, sternal process between male coxae 4; a strongly reduced gonofemorite devoid of a femoral process; a somewhat twisted solenophore that distally sheaths a rod-shaped solenomere; and well-developed lamina medialis and lamina lateralis.

FMNH
The species is most similar to Touranella moniliformis Golovatch & Semenyuk, 2018 from Cat Tien NP (Vietnam) by having a (sub-)moniliform body, poorly developed paraterga, and sparsely setose metaterga. The two species can be distinguished by the gonopod conformation, and the presence of a gonofemoral process in T. moniliformis (absent from the new species).
Regarding the absence of a gonofemoral process, the new species is similar to T. peculiaris Golovatch, 2009, but can be distinguished by a strongly reduced gonofemorite (vs considerably elongated in T. peculiaris).
Etymology. The species epithet, "champasak", is a noun in apposition and refers to the province name where the type was collected.
Description. Holotype length ca 21.6 mm, width of midbody pro-and metazona about 1.5 mm and 1.9 mm, respectively. Body brown and darkish brown, except several antennomeres; legs and sterna brownish yellow or yellow; posterior margins of prozonae and metazonae, anterior margins of metazonae, and transverse sulcus black; metaterga with a yellow axial band running from collum to telson (Fig. 2D).
Remarks. Even though the distributional gap is slightly narrowed by the occurrence of this genus in Laos, more species most probably have yet to be discovered, at least in and between southern Vietnam and Nepal, including Laos, northern Thailand, and Myanmar (Fig. 1).

An identification key to Touranella species
Since the recent key provided by Golovatch (2016), three more species have been discovered; therefore, the key is updated.

. T. gracilis
Discussion Attems (1937) distinguished the monotypic genus Touranella by a greatly shortened gonofemorite, the presence of a femoral process, and the densely setose metaterga. This diagnosis was supported by the discovery of the second species, Touranella himalayaensis Golovatch, 1994. However, other Touranella species recently found in Vietnam have revealed new diagnostic characters as in Golovatch (2009aGolovatch ( , 2009bGolovatch ( , 2016 or Semenyuk (2010, 2018). Briefly, the genus can be recognized by having a submoniliform body, poorly developed paraterga, legs with neither modifications nor adenostyles, the presence of a sternal process between coxae 4, the gonofemorite either strongly reduced or very short as compared to the solenophore, the solenomere mostly rod-shaped or subflagelliform, sheathed by the solenophore distally, and both lamina medialis and lamina lateralis well developed. Morphologically, the genus Touranella can be divided into two groups based on the presence or absence of the gonofemoral process. The first group includes the types species, T. gracilis, and four others, T. himalayaensis, T. pilosa, T. trichosa, and T. moniliformis. These species are characterized by the absence of the gonofemorite, or having it strongly reduced with a femoral process. They are also characterized by a solenophore with or without a lateral basal shoulder. The second group contains T. peculiaris, T. cattiensis, T. hirsuta, and T. champasak sp. nov., which are characterized by a very short or considerably elongated gonofemorite, without a femoral process. Given the absence of the femoral process and/or short gonofemorite, this second group is relatively close to the genus Yuennanina Attems, 1936. However, Touranella can be differentiated from Yuennanina using the first leg pair in males (femoral tubercles are absent from Touranella males, but present in Yuennanina males) and coxa (a thumb-like process is evident anteriorly in Yuennanina, but absent from Touranella). The relationship between Touranella with Yuennanina remains uncertain at this time.
The genus Touranella belongs to the tribe Alogolykini, created by Hoffman (1963: 591) for the genera Tetracentrosternus Pocock, 1895, Alogolykus Attems, 1936, and Touranella. He stated that members of this tribe could be recognized by having an extremely shortened gonofemorite; presence of a femoral process arising from the prefemorite; a slender solenophore that completely or partially sheaths the solenomere; and the first male leg pair without femoral tubercles. Jeekel (1965) noted the presence of femoral tubercles in the legs of Tetracentrosternus males and suggested a closer relationship between Tetracentrosternus and Yuennanina. Subsequently, Jeekel (1968: 127) retained these three genera (Tetracentrosternus, Alogolykus, and Yuennanina) in the tribe Alogolykini. Instead, he considered Touranella as incertae sedis, and stated that: "It is true that, as in all other Alogolykini, the gonopod femorite is reduced as in Touranella, but this is not a reason to postulate a close relationship. As a matter of fact, the tibiotarsus and its relation to the solenomerite rather strongly suggest the conditions in, e.g. the Orthomorphini, etc." (Jeekel 1968: 65). This exclusion was still retained by Hoffman (1980: 171) and Jeekel (1980: 174). However, the genus was re-assigned to the tribe Alogolykini by Golovatch (1994: 187) and Nguyen andSierwald (2013: 1179). This assignment was supported by additional newly described species (Golovatch 2009a(Golovatch , 2009bSemenyuk 2010, 2018;Golovatch 2016).
According to Likhitrakarn et al. (2013) and Golovatch et al. (2021), the tribe Alogolykini can be distinguished from its close relative, Polydrepanini, as members have a strong, rod-shaped solenomere (vs a thin, flagelliform solenomere in Polydrepanini). Both these tribes are the only components of the subfamily Alogolykinae. This tribe Alogolykini currently consists of seven genera: a monotypic Alogolykus (from Myanmar), Yuennanina (three species from southern China), Tetracentrosternus (four species from Myanmar, Thailand, and southern China), and Touranella (eight species from Nepal, Laos, and Vietnam), Singhalorthomorpha Attems, 1914 (three species from Sri Lanka), a monotypic Curiosoma Golovatch, 1984 (from India), and finally a monotypic Carlogonopus Golovatch, Aswathy, Bhagirathan & Sudhikumar, 2021 (also from India) (Golovatch et al. 2021). However, a revision of this tribe is beyond the scope of this paper, and it is suggested that phylogenetic analyses employing morphological and molecular data are needed to elucidate relationships among these genera.