Research Article |
Corresponding author: Thomas Wesener ( t.wesener@leibniz-zfmk.de ) Academic editor: Pavel Stoev
© 2021 Thomas Wesener, Nattarin Wongthamwanich, Leif Moritz.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Wesener T, Wongthamwanich N, Moritz L (2021) Description of the first species of Glomeridesmida from Thailand (Diplopoda, Glomeridesmida, Glomeridesmidae). ZooKeys 1024: 137-156. https://doi.org/10.3897/zookeys.1024.63678
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With three genera and 35 previously known species from India, SE Asia, Central and South America, Glomeridesmida are one of the least diverse Diplopoda groups. Here we describe Glomeridesmus siamensis sp. nov., the first species of the order Glomeridesmida from Thailand. The geographically nearest confamiliar species have been described from southern India, Sumatra and Java. The species is described combining photographs, light- and scanning electron microscopy of mature and younger males, females and juveniles. Several characters are illustrated for the first time for an Asian representative of the family Glomeridesmidae. In addition to the type locality of G. siamensis sp. nov. from Krabi province, locality data of unidentified Glomeridesmus from Thailand are also given. These data are providing further evidence that the Glomeridesmida are not uncommon, but overlooked as they are small and difficult to collect. The unusual telopods and other morphological characters of G. siamensis sp. nov. differ considerably from the few Glomeridesmus males described from Central and South America as well as from India, but the unclear status of two generic names available for species from Indonesia prevents us from adding another generic name to this small and understudied order.
Biodiversity, Krabi, limestone hill, soil arthropod, Southeast Asia
The third smallest millipede order (Diplopoda) in terms of diversity is the Glomeridesmida with 35 described species in three genera (
The unusual appearance of the Glomeridesmida might partly resemble the ground-plan of chilognathan Diplopoda (
SEM scanning electron microscopy;
ZCSWU Zoological Collection of Srinakharinwirot University, Bangkok, Thailand;
ZFMK-MYR collection number of the Myriapoda collection at the
Specimens were preserved in 95% ethanol and are stored in the collections of the ZCSWU and
Terminology of morphological characters follows Iniesta et al. (2012), for other morphological characters the terminology of Sphaerotheriida (
Order Glomeridesmida Latzel, 1884
Family Glomeridesmidae Latzel, 1884
The family Glomeridesmidae was partly re-characterized recently (
Glomeridesmus
Gervais, 1844a: xxvii.
Zephroniodesmus
Pocock, 1894b: 476.
Javadesmus
Verhoeff, 1929: 1377.
Glomeridesmus porcellus Gervais & Goudot, 1844 (Colombia)
Javadesmus: Glomeridesmus javanicus Attems, 1907 (Indonesia: Java)
Zephroniodesmus: Glomeridesmus sumatranus Pocock, 1894 (Indonesia: Sumatra).
30, including the species described below (
Central America and northern half of South America and the Caribbean (26); India (1); Indonesia (2); Thailand (1 described below). Unidentified specimens from various localities in SE Asia and Oceania (
The position of the new species in the genus Glomeridesmus is tentative at best. As two genus names (Zephroniodesmus, Javadesmus) synonymized with Glomeridesmus (
Holotype: 1 M, ZCSWU Myr D000011 (THAI11), Thailand, Krabi Province, N. of Krabi Town, western aspect of Tiger Cave temple (Wat Tham Suea), overgrown rocks next to rubber plantation, 08°07'23.8"N, 098°55'18.9"E. leg. 27.VII.2017, Wesener, Wongthamwanich, Nawanetiwong, Moritz.
Paratypes: 1 immature M,
Siamensis, noun in apposition, after the type locality in Thailand.
Small (5–7 mm) dark grey glomeridesmid with white legs (Fig.
Glomeridesmus siamensis sp. nov., photographs A–C male holotype (ZCSWU Myr D000011) A habitus, dorsal view B habitus, ventral view C telopods, ventral view D, E female paratype (
Based on male holotype (ZCSWU Myr D000011) and female paratype (
Measurements: Largest adult female (20+AS tergites, 35+1 leg pairs): length: ~6 mm; width (midbody): 1.0 mm. Male (19+AS tergites, 33+1+T leg pairs, holotype male): length: ~5 mm; width (midbody): 0.9 mm; immature (?) male (19+AS tergites, 32+1+T,): length: ~4 mm, width: 0.8 mm.
Colour in ethanol: Tergites and dorsal side of head grayish-brown (Fig.
Head: General shape typical for the family (Figs
Glomeridesmus siamensis sp. nov., head, SEM A, B, D male holotype (ZCSWU Myr D000011) A antennae B apical antennomeres C juvenile paratype (
Antennae consisting of seven joints, each covered with numerous setae. Size of joints 1 = 2 = 3 = 4 = 5 > 6 (Fig.
Tömösváry organs as large as antennal base, of well-rounded oval shape, interior covered by a sclerotized plate; surrounded by cuticular rim and several very short setae (Fig.
Gnathochilarium with very broad gula (hypostoma). Cardines very small, separated from basal part of gnathochilarium. Proximal fourth of mentum towards gula distinctly elevated, transverse suture visible between mentum and lamellae linguales. Lamellae linguales fused to one another, not separated by a longitudinal suture, apically with four long setae, central pair at apical margin, lateral two setae located more posteriorly. Whole surface of gnathochilarium covered with few, isolated setae. Stipites laterally without sclerotized ledge. Stipites apically with 2 extra-long setae (Fig.
Mandible: Basal joint massive, undivided (Figs
Trunk: Collum (tergite 1) wider than head, shape similar to following tergites (Fig.
Tergites 2–19 (20) very thin, difficult to distinguish from one another. Width from tergite 1 to 8 gradually increasing, then decreasing to last tergite (Figs
Pleurites of rectangular shape, posterior margin overlapping first third of subsequent pleurite (Fig.
Legs: In all except first coxae fused with stigmatic plates (typical for Glomeridesmida,
Glomeridesmus siamensis sp. nov., male holotype (ZCSWU Myr D000011), legs, SEM A leg 1, posterior view B leg 1, tarsus, arrow indicated parasitic fungi C leg 2 with gonopore, posterior view D leg 2, tarsus E leg 34, posterior view F leg 34, tarsus G sensory leg (leg 35), posterior view H sensory leg (leg 35), detail of podomeres, arrow indicated dent in podomere I. Abbreviations: I–III = podomeres, as = apical spine, cl = claw, cx = coxa, fe = femur, gp = gonopore, pn = paronychium, pof = postfemur, prf = prefemur, sp = spine, st = sternite, ta = tarsus, ti = tibia, v = stigmatic plate. Scale bars: 100 µm (A, C, E, G), 20 µm (B), 10 µm (D, F), 50 µm (H).
Leg-pair 1 with a well-rounded elliptical sternite visible in oral view. Femur 1.5 × longer than wide, tarsus slender and elongated, >7 times longer than wide (Fig.
Leg 2 (male) femur 1.7, tarsus >10 × longer than wide (Fig.
Legs 3–32 similar to first legs, e.g. midbody leg femur 1.8, tarsus >7 times longer than wide. Tarsus with 1 or 2 apical spines, claw and paronychium (Fig.
Penultimate leg with coxosternite narrow, with stigma opening and sternal part located below (instead of lateral to) of coxal part. Femur slightly longer than prefemur, 1.3 × longer than wide, tarsus shorter, >7 × longer than wide, apically with claw, apical spine and paronychium (Fig.
Ultimate leg pair (sensory leg) modified, consisting of a free large sternite, fused coxa-stigmatic plates plus 3 podomeres (Fig.
Anal shield: glabrous, with a well-rounded edge. Subanal plate located behind last pair of legs, large and hyaline.
Sexual characters: Female: second coxae on posterior side with prominent ovipositors protruding back to leg pair 5. Coxa protruding mesally as a short lobe. Ovipositors basally supported by an undivided plate (sternite?) (Fig.
Glomeridesmus siamensis sp. nov., female paratype (
Male: second coxa with gonopore located mesally (Fig.
Male telopod
consisting of syncoxite with inner horns and 4 podomeres (Figs
Glomeridesmus siamensis sp. nov., male holotype (ZCSWU Myr D000011), male sexual characters A telopod, anterior view B telopod, posterior view C gonopore on leg 2, posterior view D inner horns, anterior view. Abbreviations: I – IV = telopoditomeres, ff = immobile finger, gp = gonopore, ih = inner horns, ma = membranous area, pr = projection. Scale bars: 50 µm (A, B, D), 20 µm (C).
Telopod podomere 1 largest and most massive.
Podomere 2 wide, rectangular, apically with a large membranous area and mesally with a long and slender process. Membranous area well rounded, consisting of several inverse membranous folds. Slender process strongly elongated, as long as podomere 2, protruding between movable and immovable finger, inner surface excavated (Fig.
Glomeridesmus siamensis sp. nov., male holotype (ZCSWU Myr D000011) mouthparts A gnathochilarium, ventral view B gnathochilarium, palps and central pad, frontal view C endochilarium, dorsal view D mandibular gnathal lobe, mesal view. Abbreviations: cp = central pad, ec = endochilarium, et = external tooth, gu = gula, ip = inner palp, ia = intermediate area, it = inner tooth, LL = lamella lingualis, Lp = lateral palp, me = mentum, mp = molar plate, pL = pectinate lamellae, stp = stipes. Scale bars: 100 µm (A), 50 µm (B, D), 20 µm (C).
Podomere 3 long and slender, only 1/3 of width of podomere 2, inserting laterally on podomere 2. Posterior-lateral aspect of podomere 3 in apical part with slender, finger-shaped and well-rounded process called immobile finger, which makes up ca. half the length of podomere 3, inner surface of immobile finger excavated. Length of podomere 3, without immobile finger, 2 times longer than wide, with few isolated setae at margins in apical half (Fig.
Mobile finger (podomere 4), articulated to podomere 3 at base of immovable finger (Fig.
The immature male has the same number of tergites, but one walking leg pair less than the mature male. The immature male is almost 1/3 shorter than the mature male. Coxal pouches starting at leg pair 9 as in mature male. Last pleurite with small well-rounded indentation at posterior margin. Telopod only slightly different from mature male: process of podomere 2 shorter, podomere 3 and 4 slenderer, immobile finger almost protruding up to apical end of movable finger.
Glomeridesmus siamensis sp. nov., body-rings A, B, D juvenile paratype (
All specimens were collected by hand in the morning during rainy season in Krabi province, the second reported area for Glomeridesmida in Thailand (the first in
Habitat and type locality of Glomeridesmus siamensis sp. nov. A karstic landscape around Krabi Town, view from Tiger Cave temple (Wat Tham Suea) B, C slope underneath Tiger Cave temple at which Glomeridesmus siamensis sp. nov. was found, arrow indicates the overgrown rock from which the specimens were collected.
2 imm. F;
Descriptions of Glomeridesmus species were previously based on dubious somatic characters, i.e. species were most often separated by head morphology, body size, coloration and geography alone (e.g. Loomis 1964). The apparent paucity of males in Glomeridesmus populations makes precise taxonomic descriptions and comparisons across taxa challenging. Aside from one study of G. marmoreus Pocock, 1894 from Guadeloupe (
Contrary to the male sexual characters, the female ovipositors, while prominent, do not seem to carry much valuable information. The ovipositors of the Brazilian G. spelaeus Iniesta & Wesener, 2012 and of the Indian G. indus Carl, 1942 differ only slightly in the number of segments from G. siamensis sp. nov., for which the intraspecific variability is unknown, and which are difficult to count as basal parts are hidden.
Besides sexual characters, somatic characters also need to be assessed for their taxonomic importance. For example, it has been shown for the Glomerida and Sphaerotheriida that the endotergum, the legs and the antennae can carry relevant characters (
For the Glomeridesmida, the presence or absence of coxal pouches (Fig.
The modified ultimate leg-pair, the sensory legs, seem to contain few taxonomically important characters, but more comparisons between different species are necessary to evaluate this character. At least G. siamensis sp. nov. differs significantly in the shape of the sensory leg from other species of the genus, especially by the unusual shape of podomere 1 (Fig.
Surprisingly, the lamellae linguales of the gnathochilarium seem to carry taxonomically important characters in the Glomeridesmidae, as was discovered recently by
Based on our findings and the insights from a Myriapoda inventory of a rainforest in Java (
Only two species of Glomeridesmidae from Southeast Asia were described previously, G. sumatranus Pocock, 1894 from Sumatra and G. javanicus Attems, 1907 from Java; both are only known from female specimens. G. sumatranus was assigned to the genus Zephroniodesmus Pocock, 1894, which was later synonymized with Glomeridesmus by
We thank the Alexander-Koenig-Society Bonn for funding the expedition which led to the discovery of the species. NRCT research permits were arranged by Ms. Wananthon for which we are thankful. Special thanks to the Governor of Krabi Province for providing research facilities. Wasin Nawanetiwong accompanied our expedition and helped collecting. We feel indebted to Henrik Enghoff (