1✉ Naturalis Biodiversity Center, P.O. Box 9517, 2300 RA Leiden, the Netherlands.
2University of Montenegro, Cetinjski put bb, 81000 Podgorica, Montenegro.
3College of Natural Resources, Royal University of Bhutan, Lobesa, Punakha, P.O. 13001, Bhutan.
2022 - Volume: 62 Issue: 3 pages: 754-762https://doi.org/10.24349/pfqk-ad5d
Little research has been done on the water mites of the Himalayas. A recent paper of Gerecke & Smit (2022) treated the genus Lebertia Neuman, 1880 from Bhutan and Nepal and summarized all previous research on water mites of the Himalayas and its foothills. This is the first paper in a series of papers on water mites from Bhutan which focus mainly on the Mangde Chhu catchment area, Central Bhutan. This paper deals with the genus Sperchon Kramer, 1877, a genus with a near-cosmopolitan distribution, lacking only in the Australasian region (Smit 2020).
Thus far, only two Sperchon species were known from Bhutan (Pesic & Smit 2007), i.e. Sperchon himalayus Pesic & Smit, 2007 and Sperchon indicus Kumar, Kumar & Pesic, 2007. In this paper three new species are described, three species are reported for the first time for Bhutan and Sperchon (Hispidosperchon) indicus is synonymized with S. gracilipalpis.
Unless stated otherwise, all materials are collected by Mer Man Gurung, and this is not repeated in the text. The water mites were sorted in the field and fixed in Koenike-fluid. Most of the material has been collected in tributaries of the Mangde Chhu river in central Bhutan. The Mangde Chhu river has 1,173 high-altitude wetlands such as lakes, marshes, and brooks, with an annual flow of 11,797 million m2, and a catchment area of 7,380 km2. The river originates from the Gangkhar Puensum mountain region, and it flows through central Bhutan (Trongsa and Zhemgang districts) and leaves the country as Manas river after joining with the Drangme Chhu river. Two collection trips have been made, one pre-monsoon (April-May 2021) and one post-monsoon (October-November 2021). All material is deposited in the National Biodiversity Centre, Thimphu (NBC), a part of the paratypes and the non-type material will be lodged as a long-term loan in Naturalis Biodiversity Center (RMNH). The following further abbreviations are used: a.s.l. – above sea level; Cx-I-IV – first to fourth coxae; Dc-4-5 – dorsocentralia 4-5; Dgl-5 – dorsoglandularia 5; IV-leg-4-6 – fourth to sixth segments of fourth leg; L – length; P-1-5 – palp segments 1-5; V1– ventroglandularia 1. All measurements are in µm, measurements of palp and leg segments are of the dorsal margins, measurements of paratypes are given in parentheses. Ventral length is measured from the tip of Cx-I till posterior idiosoma margin. Numbers are given as male/female/deutonymph. All coordinates are taken with a GPS.
Material examined — Holotype female, Royal Botanical Park, Lampelri, 27.50750°N, 89.75269°E, 2667 m a.s.l., 10 Aug. 2016, leg. W. Klein (NBC).
Diagnosis — Large size (\textgreater1250), integument with longish papillae; dorsum and venter without glandularia-free platelets; P2 with an anteroventral extension with a large seta, P4 slender, ventrally with two very small setae.
Description — Female: Idiosoma dorsally 1296 long and 1199 wide, ventrally 1332 long. Integument with longish papillae. Dorsal and ventral glandularia platelets indistinct, no glandularia-free platelets present (Figure 1A). Gnathosoma 275 long, rostrum much shorter than basal part. Cx-I separated medially, Cx-III with a glandularium (Figure 1B). Genital flaps 267 long, pregenital sclerite lying under flaps and first pair of acetabula. Excretory pore sclerotized. Length of P1-5: 56, 184, 251, 352, 62. P2 with an anteroventral extension with a large seta, P4 slender, ventrally with two small setae (Figure 1C). Length of I-leg-4-6: 300, 316, 275. Length of IV-leg-4-6: 510, 454, 373. All fourth and fifth segments of the legs dorsally with a row of pectinate setae (Figure 1D). Leg claws with one clawlet and a small claw blade.
Etymology — Named for its large size.
Discussion — It's large size, the absence of glandularia-free platelets, the very long and slender P4 and the longish papillae will distinguish the new species from all other Sperchon species. Sperchon glandulosus Koenike, 1886 and S. thienemanni Koenike, 1907 are both large species, but both differ in P4 with stout ventral setae. Moreover, the excretory pore of S. thienemanni is unsclerotized.
Material examined — Holotype male, Khabab Chhu, Bhutan, 27.48492°N, 90.33490°E, 2500 m a.s.l., 14 May 2021, leg. M.M. Gurung (NBC). Paratypes: seven males, five females, same data as holotype (NBC); five males, two females, same location as holotype, 7 Nov. 2021 (NBC); one male, Nika Chhu, Bhutan, 27.526008°N, 90.299471°E, 2609 m a.s.l., 10 May 2021, leg. M.M. Gurung (NBC); two males, Chendebji Chhu, 27.47692°N, 90.35265°E, 2483 m a.s.l., 8 Nov. 2021, leg. M.M. Gurung (NBC).
Other material – 4/5/0, Chuserbu Chhu, 27.502465°N, 90.317826°E, 2666 m a.s.l., 13 May 2021; 0/1/0, Chumpigang Chhu, 27.31608°N, 90.58071°E, 1018 m a.s.l., 2 Nov. 2021; 3/0/0, Rukhubju Chhu, 27.51174°N, 90.29711°E, 2587 m a.s.l., 5 Nov. 2021; 1/1/0, Chuserbu Chhu, 27.50246°N, 90.31782°E, 2666 m a.s.l., 6 Nov. 2021
Diagnosis — Dorsal platelets relatively large (length up to 160), with an unpaired central platelet (diameter 140); P2 with a large anteroventral extension with a stout seta, P4 ventrally with two stout setae lying relatively close to each other.
Description — Male: Integument papillate. Idiosoma dorsally 753 (570-778) long and 720 (583-729) wide, ventrally 818 (632-842) long. Dorsum with relatively large glandularia (length up to 160), reddish platelets (but yellowish to yellowish-brown in young specimens and in a few mature specimens) and three pairs of platelets without glandularia; preocularia on a small platelet, postocularia on a relatively large platelet; centrally with a large unpaired platelet, diameter 140 (Figure 2A). Occasionally Dgl-3 fused with lateral platelet without glandularia (Figure 2C). Gnathosoma stocky, 158 long. Venter with relatively large platelets. Cx-I medially separated (Figure 2B), Cx-III witht a glandularium. Genital field with three pairs of acetabula, middle acetabula elongated; genital flap 194 long, medial margin with a row of setae (Figure 2F). Excretory pore sclerotized. Length of P1-5: 28, 90, 109, 152, 35. P2 with an anteroventral extension and a stout seta, P4 ventrally with two stout, blunt setae (Figure 2D-E). Length of I-leg-4-6: 160, 180, 164. Length of IV-leg-4-6: 259, 251, 227. II-IV-leg with pectinate setae (Figure 2H). Leg claws with three clawlets, the most ventral one blunt.
Female: Idiosoma dorsally 940 (612-846) long and 899 (632-818) wide, ventrally 980 (697-899) long. In most aspects similar to male. Central unpaired dorsal platelet smaller compared to male. Genital flap 203 long (Figure 2G). Length of P1-5: 36, 130, 150, 208, 49. Palp as in male. Length of I-leg-4-6: 190, 212, 180. Length of IV-leg-4-6: 308, 283, 267. Legs as in male.
Etymology — Named for the red-coloured platelets.
Discussion — Sperchon gracilipalpis Lundblad, 1941 has more or less similar configuration of the dorsal platelets, but these platelets are much smaller compared to the new species. Moreover, the palp of S. gracilipalpis has P4 ventrally with only small setae, which are more separated from each other compared to the new species, and the integument is reticulated. Sperchon noshaqensis Imamura, 1966 has a more or less similar palp, but P3 is slenderer. Unfortunately, Imamura (1966) didn′t describe the dorsum of S. noshaqensis, but according to Pešić & Smit (2020) the dorsum is without sclerotized muscle attachment plates (although their assignment of their specimens is uncertain).
Material examined — Holotype male, Chumpigang Chhu, Bhutan, 27.31608°N, 90.58071°E, 1018 m a.s.l., 8 May 2021 (NBC).
Diagnosis — Dorsal platelets large, especially postocularia platelets and Dc-5, the latter fused with Dgl-5; small ventral setae of P4 relatively close to each other.
Description — Male: Idiosoma dorsally 705 long and 616 wide, ventrally 753 long. Integument reticulate. Dorsal platelets large, postocularia platelets and Dc-5 are the largest platelets (Figure 3A). All dorsal platelets paired except one platelet posterior to postocularia platelets. Gnathosoma 220 long, rostrum shorter than basal part. Cx-I separated medially, Cx-III with a glandularium (Figure 3B). Excretory pore sclerotized, lateral to excretory pore a pair of large platelets. Length of P1-5: 34, 110, 156, 208, 41. P2 with a large anteroventral extension with one long and one shorter seta; P3 ventrally somewhat bulging; ventral margin of P4 with two small setae (Figure 3C). Length of I-leg-4-6: 188, 166, 154. Length of IV-leg-4-6: 288, 275, 259. Legs-II-IV with pectinate setae (Figure 3D). Leg claws with one clawlet and without claw blade.
Etymology — Named after the country where the new species has been collected.
Discussion — The new species is most similar to S. gracilipalpis Lundblad, 1941, but differs in the following characters (those of S. gracilipalpis in parenthesis): dorsum with large platelets (smaller platelets), the ventral setae of P4 are lying close to each (more separated), ventral margin of P3 is convex (straight), P4 208 long (shorter, 136 long) and the gnathosoma is large, 220 long (smaller, 143 long).
Material examined — 1/3/0, Berti Chhu, 27.16264°N, 90.66003°E, 590 m a.s.l, 26 Apr. 2021; 0/1/1, Takabi Chhu, 27.14782°N, 90.68833°E, 543 m a.s.l., 30 Apr. 2021; 1/12/0, Berti Chhu, 27.16264°N, 90.66003°E, 590 m a.s.l., 25 Oct. 2021; 2/0/3, Bipgang Chhu, 27.15720°N, 90.66721°E, 586 m a.s.l., 25 Oct. 2021.
Description — Female: Idiosoma dorsally 713 (575-680) long and 535 (437-527) wide, ventrally 753 (624-745) long. Dorsum with a pair of conspicuous large platelets near Dgl-5 (Figure 4A). Gnathosoma stocky, 196 long, rostrum shorter than basal part. Cx-I separated medially, Cx-III with a glandularium. Genital flaps 128 long. Length of P1-5: 34, 119, 146, 128, 32. P2 with an anteroventral extension with a long and short fine setae, ventral margin of P4 with one small, stout setae, one very small stout seta more anteriorly and distanced from ventral margin (Figure 4B); P4 shorter than P3, ventrally with one stout seta, more anteriorly and distanced from ventral margin a smaller stout seta. Excretory pore sclerotized.
Male: See Pešić et al. (2019a).
Discussion — Thus far, a limited number of specimens were known of this species, and therefore a number of additional measurements are given above. The large and conspicuous Dc-5 in combination with the setation of P4 (especially the small anterior seta distanced from the ventral margin) are diagnostic. Specimens from China have larger dorsal and ventral platelets compared to the specimens from India and Bhutan, but their configuration is similar (Zhang and Jin 2010).
Distribution — Uttarakhand State, India (Kumar et al. 2007; Pešić et al. 2019b); Hubei Province, China (Zhang and Jin 2010); Bhutan (this study).
Sperchon indicus Kumar, Kumar and Pesic, 2007 – new syn.
Material examined — 0/2/0, Maidagang Chhu, 27.12761°N, 90.71560°E, 554 m a.s.l., 24 Apr. 2021; 0/2/1, Dakpay Chhu, 27.14621°N, 90.69220°E, 539 m a.s.l., 1 May 2021; 0/1/0, Kartigang Chhu, 27.27896°N, 90.63088°E, 1456 m a.s.l., 7 May 2021; 0/1/2, Chumpigang Chhu, 27.31608°N, 90.58071°E, 1018 m a.s.l., 8 May 2021; 1/2/0, Nika Chhu, 27.526008°N, 90.299471°E, 2609 m a.s.l., 10 May 2021; 0/1/0, Rukhubji Chhu, 27.51174°N, 90.29711°E, 2587 m a.s.l., 12.v.2021; 0/3/0, Chuserbu Chhu, 27.502465°N, 90. 317826°E, 2666 m a.s.l., 13 May 2021; 1/0/1, Maidagang Chhu, 27.12761°N, 90.71560°E, 554 m a.s.l., 20 Oct. 2021; 1/0/0. Berti Chhu, 27.16264°N, 90.66003°E, 590 m a.s.l., 25 Oct. 2021; 0/1/0, Takabi Chhu, 27.14782°N, 90.68833°E, 543 m a.s.l., 26 Oct. 2021; 0/2/0, Dakpay Chhu, 27.14621°N, 90.69220°E, 539 m a.s.l., 27 Oct. 2021; 4/0/1, Chumpigang Chhu, 27.31608°N, 90.58071°E, 1018 m a.s.l., 2 Nov. 2021; 0/2/0, Nika Chhu, 27.52601°N, 90.29947°E, 2609 m a.s.l., 4 Nov. 2021; 1/0/0, Rukhubji Chhu, 27.51174°N, 90.29711°E, 2587 m a.s.l., 5 Nov. 2021; 3/4/0, Chuserbu Chhu, 27.50246°N, 90.31782°E, 2666 m a.s.l., 6 Nov. 2021; 2/2/0, Chendebji Chhu, 27.47692°N, 90.35265°E, 2483 m a.s.l., 8 Nov. 2021.
Sperchon indicus – Holotype female, Khanda Gad stream, Garhwal Himalayas, India, 30°12′N 78°43′E, no date (slides RMNH.ACA.P.67323, RMNH.ACA.P.67324).
Discussion — Kumar et al. (2007) stated that S. indicus from India, differed from S. gracilipalpis in the presence of a sclerotized excretory pore. However, examination of the holotype of S. gracilipalpis showed that this species has a sclerotized excretory pore too (Figure 5A). In all other aspects (slender palp, configuration of dorsal platelets, gnathosoma with a short rostrum), S. indicus is similar to S. gracilipalpis. Therefore, we propose the synonymization of S. indicus with S. gracilipalpis.
In one male from Nika Chhu the unpaired dorsal platelet is fused with Dc-4 (Figure 5B), but the shape of dorsal platelets in Sperchon is somewhat variable.
Distribution — Burma (Lundblad 1967, 1969); Uttarakhand State, India (Kumar et al. 2007; Pešić et al. 2019a,b); Bhutan (Pesic and Smit 2007; this study).
Material examined — 01/0, Royal Botanical Park, Lampelri, 27.50750°N, 89.75269°E, 2667 m a.s.l., 10 Aug. 2016, leg. W. Klein.
Distribution — Burma (Lundblad 1967); Bhutan (this study).
The fieldwork of this research was made possible by grants of the National Geographic Society (NGS-72271C-20) for a project titled ''Exploring the invertebrate diversity of the last virgin rivers of Bhutan, the Eastern Himalayas″ and a grant from the foundation Pro Acarologia Basiliensis (Basel). Vincent Kalkman (RMNH) coordinated the contact between Naturalis Biodiversity Center and institutions in Bhutan and assisted with the logistics. Moreover, we are indebted to Wim Klein and Oscar Vorst (RMNH) for collecting a number of water mites in Bhutan, and Mer Man Gurung would like to thank Cheten Dorji for his guidance and company during the collecting trips.