A new species of the millipede genus Cryptocorypha Attems, 1907, from northern Thailand (Polydesmida, Pyrgodesmidae)

Abstract The millipede family Pyrgodesmidae and the genus Cryptocorypha are recorded from Thailand for the first time, being represented there by C.enghoffisp. n. The new species is distinguished by the evident apicodorsal trichostele on the last tibia of both sexes and the gonopodal telopodite being particularly complex, quadripartite, consisting of the longest, mesal, suberect solenomere branch; a slightly shorter, similarly slender, acuminate endomere branch tightly appressed to the solenomere; a somewhat shorter, caudal, strongly curved, armed exomere process; and a very distinct, low, lateral, sac-shaped velum at their base. This situation strongly resembles the one observed in the geographically closest C.perplexa Golovatch & VandenSpiegel, 2015, from Myanmar, but the shapes and armament of all outgrowths of the gonopodal telopodite are clearly different. A key to all three Cryptocorypha pecies known from Indochina or Myanmar and an updated checklist of all 21 species of the genus are provided.


Introduction
The genus Cryptocorypha Attems, 1907, is one of the few relatively speciose genera of the mainly tropical millipede family Pyrgodesmidae which is among the largest in the entire class Diplopoda. The family Pyrgodesmidae currently comprises more than 170 genera and nearly 400 species (Minelli 2015. Cryptocorypha has recently been reviewed, rediagnosed (Golovatch et al. 2011b, 2013, Golovatch and VandenSpiegel 2015, and shown to encompass 20 species ranging from central and eastern tropical Africa, through India, Sri Lanka and Myanmar, to East Asia, southern China, Indochina, western Indonesia, and even Melanesia ( Table 1).
Most of the congeners tend to show very narrow distributions, with only a single species, C. ornata (Attems, 1938), being extremely widespread on tropical islands and archipelagos in the Indian and Pacific oceans, apparently due to anthropo-and/or ornithochory (Minelli 2015, Golovatch et al. 2017).
The present paper puts on record a new species of this genus, the first to be found in Thailand. An updated checklist of all 21 species of Cryptocorypha known to date and a key to all three congeners from Indochina or Myanmar are also provided.

Materials and methods
The specimens were hand-collected from Huai Hong Khrai Royal Development Study Centre during the rainy season (during the months of April to October in 2015 and 2016). Live animals were photographed in their habitats and then taken for photography in the laboratory using a Canon 70D digital camera with a Canon EF-S 60mm f/2.8 Macro USM lens. After that, the specimens were preserved in 75% ethanol. The morphological characters were studied in the laboratory using uncleaned specimens and an Olympus stereo microscope. The terminology used follows that accepted in the most recent publications (Golovatch et al. 2011b, 2013, Golovatch and Van-denSpiegel 2015. Scanning electron micrographs (SEM) were taken with a JEOL, JSM-5410 LV microscope with gold coating, and the material returned from stubs to alcohol after examination. Images of the holotype habitus were taken in the laboratory and assembled using the "CellD" automontage software of the Olympus Soft Imaging Solution package and the gonopods of a paratype were dissected and illustrated under Euromex iScope microscopes. The holotype and most of the paratypes are housed in the Museum of Zoology, Chulalongkorn University (CUMZ), Bangkok, Thailand. A few paratypes have also been donated to the collections of the Zoological Museum, State University of Moscow, Russia (ZMUM), Natural History Museum of Denmark, University of Copenhagen, Denmark (ZMUC), Naturhistorisches Museum Wien, Austria (NHMW), and Natural History Museum, London, Great Britain (NHML), as indicated in the text.

Family Pyrgodesmidae Silvestri, 1896
Genus Cryptocorypha Attems, 1907 Diagnosis. The genus is characterized within Pyrgodesmidae by an unusually flat body with 19 or 20 segments (either in both sexes or 19 solely in the male) and only a slightly convex dorsum, coupled with 6+6 faint lobulations or 11 radii at a regularly rounded anterior margin of a flabellate collum that fully covers the head from above; usually three or four (rarely five) more distinct lobulations at the lateral margins of poreless and pore-bearing paraterga, respectively; a normal pore formula (5, 7, 9, 10, 12, 13, 15-18(19)) with the ozopores not borne on porosteles, but opening flush on the dorsal surface at the base of the penultimate lobulation; the absence of anterior and the presence of only very few (1-2) caudal lobulations; the development of 2-3 transverse, often irregular rows of small and non-differentiated knobs/tuberculations on each postcollum metatergum; and a dorsally fully exposed epiproct. The last tibia in the male or even in both sexes is often, but not always, with a conspicuous, long, setigerous, apicodorsal cylinder (= trichostele). The gonopods are with relatively small coxae and a shallow gonocoel that leaves the telopodites very strongly exposed and in situ held (sub)parallel to each other; each telopodite is 2-, 3-or 4-partite, with a strongly developed, slender, often fimbriate, mesal solenomere branch (usually the longest) and a typically sac-shaped velum at its base, sometimes also with 1-2 adjacent processes (exo-and/or endomere, depending on position) . Name. Honours Henrik Enghoff, a globally renowned specialist in Diplopoda and one of the pioneers of diplopodological research in Thailand.
Diagnosis. Differs from other species of the genus by the presence of 20 body segments in both sexes, coupled with an evident apicodorsal trichostele on the last tibia of both sexes (Fig. 4F) and in the gonopod structure being particularly complex, similar to that of C. perplexa Golovatch & VandenSpiegel, 2015, but differs clearly in the shapes and armament of all four main outgrowths of the telopodite (Fig. 4A-D).
Coloration of live animals uniformly reddish to purplish red (Fig. 1A, B), antennae, legs, and venter mainly lighter, yellowish to reddish (Fig. 1A); coloration in alcohol, after three years of preservation, faded to reddish (Fig. 1C-E) or light brown, antennae and legs light red to light brown, while venter yellowish to nearly pallid (Fig. 1D, E).
Postcollum paraterga very broad, thin and slightly, but clearly lobulate laterally (Figs 1A, C, 2A, B, 3A, B, D, G, H, J), with three lobulations in all poreless segments, four lobulations in all pore-bearing ones, all also delimited by very long, rather evident radii both dorsally and ventrally; anterior marginals absent, but two caudal marginals evident.
Remarks. This new species was found walking on a rock surface (Fig. 1B). The air was very humid, this being characteristic of the rainy season. The specimens were found in the Dry Dipterocarp Forest at the Huai Hong Khrai Royal Development Study Centre. This study centre was established under the royal initiative in 1982 in the area of Khun Mae Kuang National Forest Reserve, Chiang Mai Province for conducting research and experimentation using appropriate progressive methods which suited the development needs of the Northern Region, especially the conservation of watersheds, reforestation and agricultural development. It covers approximately 8,500 rai (1,360 hectares).

Conclusions
The diplopod diversity in Thailand has hitherto been reported to total 228 species (Likhitrakarn et al. 2017, Srisonchai et al. 2018a, b, c, d, Pimvichai et al. 2018. Given that only a single species, C. enghoffi sp. n., of the very large micropolydesmid (= small-bodied) family Pyrgodesmidae has been reported from Thailand, there can be no doubt whatsoever that many more micropolydesmids, including those representing not only the Pyrgodesmidae, but also such taxonomically relatively poorly assessed families as Cryptodesmidae, Opisotretidae, Trichopolydesmidae, and Haplodesmidae still await discovery and description in Thailand and the adjacent countries of Southeast Asia.