Schizoturanius kitabensis ( Gulička, 1963 )

VandenSpiegel, D. & Golovatch, S. I., 2023, On two poorly-known species of the millipede family Polydesmidae (Diplopoda: Polydesmida) from Central Asia, Arthropoda Selecta 32 (1), pp. 15-22 : 15-18

publication ID	https://doi.org/10.15298/arthsel.32.1.02
DOI	https://doi.org/10.5281/zenodo.15557545
persistent identifier	https://treatment.plazi.org/id/E14E87DE-662D-FFD7-0528-F970FBECA148
treatment provided by	Felipe
scientific name	Schizoturanius kitabensis ( Gulička, 1963 )
status

Treatment

Schizoturanius kitabensis ( Gulička, 1963) View in CoL

Figs 1–14 View Figs 1–9 View Figs 10–14 , 28, 29 View Figs 28–31 .

Turanodesmus kitabensis Gulička, 1963: 325 View in CoL (original description).

Schizoturanius kitabensis View in CoL — Lokšina, Golovatch, 1979: 384 (listing and an indirect transfer); Read, Golovatch, 1994: 65 (listing); Nefediev, 2022: 265 (listing and key).

MATERIAL EXAMINED. Syntypes: 2 ♂♂, 1 ♀ ( SMNPS), [ USSR], Uzbek SSR (now Uzbekistan), Kitab, near irrigation stream , 31. V.1962, L.M. Semenova leg.

According to Gulička [1963], the type series of Turanodesmus kitabensis consisted of the holotype ♂, the allotype ♀, and further 5 ♂♂ and 6 ♀♀ paratypes. According to A. Mock (in litt.), however, the SMNPS collection presently comprises 10 ♂♂, 8 ♀♀ and 1 juvenile, all contained in a single jar. Because Gulička seems to have failed to select, separate and properly label the holo- and allotype, for the time being it appears better to treat everything as syntypes. Lectotype designation thus remains to be formalized by other colleagues, if necessary.

DESCRIPTIVE NOTES. Because the original description [ Gulička, 1963] was too succinct and accompanied by only a single crude sketch of a gonopod, we profit by providing here both a short redescription and, above all, a sufficiently detailed iconography ( Figs 1–14 View Figs 1–9 View Figs 10–14 , 28, 29 View Figs 28–31 ).

Adult body ca 10 (♂) or 9 mm long (♀), and 0.8 mm wide (♂, ♀) (vs 8–9.5 mm long in the original description). Coloration in alcohol uniformly light yellow-pink ( Figs 1, 2 View Figs 1–9 ) (vs yellow-white with rusty tint in the original description). Body with 20 segments. Tegument dull, texture very delicately shagreened. Head pilose nearly throughout, with squarish genae and three distinct central teeth at anterior margin. Antennae long and only slightly clavate.

In width, collum <ring 2 <3=4 <head = 5=15, thereafter body gradually tapering towards telson ( Figs 3–5 View Figs 1–9 ). Paraterga poorly developed, but evident, set high (at about upper third of midbody height), starting with collum, mostly subhorizontal vs a clearly convex dorsum, usually with three or four small, lateral, setigerous indentations. Caudolateral corners of paraterga rounded in a few anterior rings, then increasingly angular and obtuse to finally subrectangular and nearly pointed in rings 17–19, not extended past rear tergal margin, devoid of calluses. Pore formula normal, ozopores small, lateral, located in posteriormost marginal indentation. Metatergal sculpture typical, poorly-developed, obliterate, with three transverse rows of typical (= polydesmid), setigerous, polygonal bosses ( Figs 3–5 View Figs 1–9 ). Tergal setae very short, slightly longer only on collum and a few caudalmost rings, subclavate and finely barbed ( Fig. 7 View Figs 1–9 ), often obliterate. Stricture between pro- and metazona wide, shallow and as finely microgranulate as prozona ( Fig. 4 View Figs 1–9 ). Limbus very thin, microtrichous, microtrichs often being bifid ( Fig. 8 View Figs 1–9 ). Pleurosternal carinae absent. Epiproct short, conical, carrying a group of four setiform spinnerets at tip, pre-apical lateral papillae very small ( Fig. 6 View Figs 1–9 ). Hypoproct semi-circular; caudal, paramedian, setigerous papillae small and well-separated ( Fig. 6 View Figs 1–9 ).

Sterna without modifications, densely setose; sternum between ♂ legs 9 unmodified as well. Legs generally rather long and slender (♂, ♀), only slightly incrassate ( Figs 1, 2, 9 View Figs 1–9 ), ca 1.3–1.4 times as long as midbody height, densely setose, microgranulate ventrally, but devoid of evident sphaerotrichomes (♂, ♀); prefemora devoid of lateral bulges ( Fig. 9 View Figs 1–9 ).

Gonopods ( Figs 9–14 View Figs 1–9 View Figs 10–14 ) clearly curved ventrad, in situ crossing each other only distally, with large, subquadrate coxites (cx) strongly fused medially at base, each carrying only a few setae ventrolaterally and a large round lobe (ro) distoventrally; a long unciform cannula (ca) as usual. Telopodites (te) elongated, but rather stout, subfalcate, prefemorite (= densely setose part) strongly delimited, almost half as long as entire te; seminal groove running entirely mesally until distally squeezing neatly between similarly shaped and long endomere (en) and exomere (ex) branches to move onto en at a nearly right angle and to almost immediately empty into a small, but evident accessory seminal chamber (neither visible in SEM micrographs, but shown in Gulička [1963]), the latter structure opening through a distinct hairy pulvillus (pu) at base of an unusually prominent, tubiform, membranous process (a), a being apparently hollow at tip and supplied with a strong, mesal, distad oriented spine (sp) (apparently, homologue to minute spinous process, or msp, in Nefediev [2022]) at its base and, even more basally, with another, even stronger, endomere process (ep) directed basad. Apical halves of both en and ex subequal, subfalcate and rounded at tip, but basal half of ex mesally showing an evident tooth (d, obviously homologue to subtriangular inner plate, or sip, in Nefediev [2022]) and a small, more basal step (t, obviously homologue to oval inner plate, or oip, in Nefediev [2022]).

♀ epigynal ridge (r) behind vulvae very low and inconspicuous; vulvae simple, operculum (op) small, anterior, as usual, while bursa (bu) densely setose and with a rather low and rather simple axial ridge ( Figs 28, 29 View Figs 28–31 ).

REMARKS. There are several characters that make S. kitabensis clearly disjunct compared to all or most of the remaining eight species that Nefediev [2022] accepted in his recent review of the genus Schizoturanius : (1) S. clavatipes (Stuxberg, 1876) , from both Western and Central Siberia, Russia; (2) S. dmitriewi (Timotheew, 1897) , from central and eastern Ukraine, southwestern and central European Russia, and the Altai Mountains, southwestern Siberia, Russia; (3) S. dshungaricus Golovatch, 1979 , from the Dzhungarsky Alatau Mountains, eastern Kazakhstan; (4) S. krugovae Nefediev, 2022 , from the Altai Mountains, southwestern Siberia, Russia; (5) S. levis Mikhaljova, 2013 , from the Zaysan District of eastern Kazakhstan; (6) S. montivagus Lohmander, 1933 , from near Bishkek, Kyrgyzstan; (7) S. strongylosomoides (Attems, 1904) , the type-species, from near Przhevalsk (now Karakol), Kyrgyzstan; and (8) S. tabescens (Stuxberg, 1876) , from both Western and Central Siberia, Russia. Thus, sexual dimorphism in S. kitabensis is far from striking, the legs being subequally slender, only slightly incrassate and long in relation to body height in both sexes ( Figs 1, 2 View Figs 1–9 ), even though ♀♀ are as usual slightly larger and bulkier than ♂♂. In most Polydesmidae where the ♀ sex is known even superficially the ♂ legs are typically longer and considerably incrassate compared to the ♀ (e.g., Figs 15, 16 View Figs 15–22 ). However, this trait is quite variable, including the laterally bulged vs non-bulged ♂ prefemora or the presence vs absence of sphaerotrichomes at least on some ♂ legs, and can therefore hardly be taken as a genus-level character, instead rather reflecting a trend. For example, the same trend concerns the very large Asian genus Epanerchodus (see also below) which includes>120 species, both epigean and cavernicolous (e.g., Liu, Golovatch [2018]).

Another distinct character of Schizoturanius kitabensis as opposed to all congeners but S. tabescens is the presence of laterally indentate paraterga. These are mostly smooth in Schizoturanius spp. Yet this character, as well as the metaterga being totally smooth to clearly tuberculate, appear to be highly variable within many genera of Polydesmidae , including the rather species-rich northern Asian Jaxartes Verhoeff, 1930 (e.g., Spelda et al. [1999], Antić et al. [2019]) and Uniramidesmus Golovatch, 1979 (e.g., Mikhaljova [2017]). Species of the former genus show smooth to tuberculate metaterga, and laterally smooth to indentate paraterga, vs smooth to tuberculate metaterga, but laterally always indentate paraterga in Uniramidesmus .

The tergal setae in Schizoturanius kitabensis seem to be quite particular, being short, clavate and finely barbed ( Fig. 7 View Figs 1–9 ), this obviously being characteristic of the species. However, we know too little yet about the fine structure of the metatergal setae of most of the other congeners. At least in S. krugovae , the tergal setae seem to be simple and nonclavate [ Nefediev, 2022], same as in some Jaxartes [ Antić et al., 2019] and Epanerchodus species ( Fig. 17 View Figs 15–22 ).

The same concerns the limbus which is microtrichous in Schizoturanius kitabensis ( Fig. 8 View Figs 1–9 ), vs nearly entire in S. krugovae [ Nefediev, 2022], typically entire in Jaxartes [ Antić et al., 2019] or densely microspiculate to microtrichous in Epanerchodus species (e.g., Figs 21, 22 View Figs 15–22 and Liu, Golovatch [2018]).

What seems to be especially noteworthy, however, is that the gonopod structure of Schizoturanius kitabensis is also highly peculiar, being perhaps the most elaborate among congeners. Against the background of all main structural features characteristic of the genus [ Nefediev, 2022], such as the biramous gonotelopodite branching into an exo- and an endomere (ex and en, in this case both similarly shaped and long), the course of the seminal groove, the presence of an accessory seminal chamber and a hairy pulvillus at the base of the endomere etc., a new, tubiform, membranous process (a) on en is not only developed, but it is unusually prominent and supplied with a strong, basal, mesal, distad oriented spine (sp), vs a relatively short and simple endomere process (ep), yet this as usual lying more basally and directed basad ( Figs 10–14 View Figs 10–14 ). In addition, the basal half of ex in S. kitabensis shows an evident mesal tooth (d) and, more basally, a step (t) ( Figs 10–14 View Figs 10–14 ), both easy to homologize with similar structures in other congeners. However, because these variations seem to be but species-specific, like is the unusually strongly shortened and dorsad expanded gonofemorite in S. tabescens [ Mikhaljova, 2017], we are inclined to follow Nefediev [2022] in treating both S. kitabensis and S. tabescens as species, however disjunct, of Schizoturanius . Creating two monotypic genera to solely accommodate each of these two somewhat aberrant species seems superfluous, adding nothing to the understanding of their relationships and phylogeny.

Kingdom	Animalia
Phylum	Arthropoda
Class	Diplopoda
Order	Polydesmida
Family	Polydesmidae
Genus	Schizoturanius