Epanerchodus orientalis Attems, 1901
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https://dx.doi.org/10.3897/zookeys.93.1167 |
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https://treatment.plazi.org/id/43192597-324A-3CC4-94E8-46D9C06FCDC2 |
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Epanerchodus orientalis Attems, 1901 |
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Epanerchodus orientalis Attems, 1901 View in CoL Figs 2436
Epanerchodus orientalis orientalis - Wang 1956: 155 (R); Wang 1963: 91 (R)
Epanerchodus orientalis takakuwai - Wang 1958: 341 (R)
NB:
Complete catalogue information referring to this species can be found in Murakami (1969)
Material examined:
10 ♂ (TFRI), 1 ♂ (NMNS-6557-001), 1 ♀ (NSYSU), 2 ♂ (MNHN JC 333), Taiwan, Taichung County, Shengguang, 25.04.2003; 2 ♀ (TFRI), same locality, 26.03.2003; 1 ♀ (TFRI), same locality, 24.09.2002; 4 ♂ (TFRI), 1 ♂ (NMNS-6557-002), same locality, 24.07.2003, all leg. W.C. Yeh; 2 ♂, 1 ♀ (TFRI), 2 ♂, 1 ♀ (IBSS), Ilan County, Fushan, 23.03.2003; 2 ♀ (NMNS-6557-003), same locality, 18.05.2001; 5 ♂, 1 ♀ (TFRI), same locality, 19.06.2001; 1 ♂ (TFRI), same locality, without date, all leg. J.T. Chao; 1 ♂ (ZMUM), same locality, 20.11.2001, leg. S.S. Lu; 52 ♂, 17 ♀, 4 fragm. (TFRI), 2 ♂ (ZMUC), 2 ♂ (NSYSU), Ilan County, Tatong Township, near Lakes Jialuohu, ca 2,250 m, 4.06.2003; 1 ♀ fragm. (TFRI), same locality, 28.04.2003; 8 ♂, 6 ♀ (TFRI), same locality, 20.06.2002; 1 ♂ (ZMUM), same locality, 25.04.2003; 1 ♂ (TFRI), same locality, 23.07.2002, all leg. Y.M. Chen; 1 ♀ (NSYSU), Taitung County, Yanping Township, Yanping Forest road, ca. 1,250 m, 3.06.2003, leg. M.H. Hsu; 2 ♂ (NSYSU), Hualien County, Fongbin Township, Guangfong Highway, ca 300 m, 6.05.2009; 1 ♀ (NSYSU), same County, Shoufang Township, ca. 230 m a.s.l., 5.05.2009, all leg. M.H. Shu; 2 ♀ (NMNS-6557-004), Pingtung County, Chaozhou Township, Si-Lin, 1.06.1999, leg.?; 1 ♀ (NMNS-6557-005), Kaohsiung County, Taoyuan, Provincial Road No. 20, near 142.5 km road-sign, 3.09.2009, leg. C.Y. Huang.
Diagnosis:
Differs from the other Epanerchodus species known from Taiwan in the variable, mostly medium size, coupled with the caudal corner of most of the paraterga being pointed, and in the gonopod telopodite being relatively slender, complex, highly variable in shape and armature (see also Key below).
Redescription:
Length of both sexes ca 11-19 mm; width of pro- and metazona varying between specimens from 0.8-1.8 to 1.2-3.0 mm, respectively. Usually ♂♂ somewhat smaller than ♀♀. Coloration in alcohol from uniformly pallid (faded?) to light (reddish- to grey-) brown; in the latter case, venter and legs light grey to yellow (Figs 24-31). Body with 20 segments. Tegument mainly dull, at most slightly shining, texture very delicately alveolate. Labrum, frons and vertex densely pilose; epicranial suture clear but thin; no ridges above antennal sockets; isthmus between antennae considerably broader than diameter of antennal socket (Fig. 29). Antennae long and only slightly clavate (Figs 24, 25, 28), reaching behind end (♂) or midway (♀) of segment 4 dorsally; antennomere 3 longest, 5th highest (Figs 25, 28); antennomeres 5 and 6 each with a small, compact, distodorsal group of bacilliform sensilla; antennomere 7 with a minute dorsoparabasal cone and a distodorsal group of microscopic sensilla.
In width, either collum ≤ segment 2 = 3 <4 <head = 5(6)-15(16), or segment 2 = 3 <collum <head = 4 <5-15(16) (both sexes), thereafter body gradually tapering towards telson. Paraterga strongly developed, starting from collum, subhorizontal, set high but always lying slightly below a faintly convex dorsum; front shoulders and caudal edge nearly straight on several postcollum metaterga, caudal corner always pointed. Collum (Fig. 28) nearly regularly elliptical, with an incision near caudal corner and three transverse rows of setae (6+6, 4+4 and 3+3). Starting from segment 5, paraterga extending increasingly beyond rear tergal contour, mostly subspiniform (Figs 25-28). Starting from segment 2, all poreless segments with three, all pore-bearing ones with four, small but evident incisions, each usually bearing a small seta on top at lateral margin. Pore formula normal, ozopores evident, dorsal, located in front of 4th indentation. Metatergal sculpture typical, rather well developed, with three transverse rows of setiferous, polygonal bosses (Figs 25-28). Tergal setae short, mostly retained, a little longer only on collum and in rear row on metatergum 19 (Figs 25, 27). Stricture between pro- and metazona rather obscure, wide, smooth and polished. Limbus very thin, microdenticulate. Pleurosternal carinae absent. Epiproct rather short, conical (Fig. 31), preapical papillae evident. Hypoproct semi-circular; caudal, paramedian, setiferous papillae evident and well-separated.
Sterna without modifications (Figs 29, 31), densely setose. Epigynal ridge very low, regularly rounded. Legs long and slender (Figs 28, 29), ca 1.8-1.9 (♂) or 1.2-1.3 (♀) times as long as midbody height; ♂ legs evidently enlarged, prefemora only slightly swollen dorsally, femora ventro-parabasally with shorter bifid setae replaced by sphaerotrichomes in remaining parts of femora, as well as on entire postfemora, tibiae and tarsi.
Gonopods (Figs 32-36) with large, subquadrate, medially fused coxae carrying a few long setae ventrally. Telopodite stout to rather slender, subfalcate, prefemoral (densely setose) portion one-third to half as long as entire telopodite; seminal groove running mesally over much of its extent, only distally moving frontally to recurve first laterad and then mesad, squeezing neatly between a simple, more or less rudimentary to completely reduced exomere (ex) and a more complex, branching and always well-developed endomere (en), then groove continuing to a considerable extent basad to end into a large accessory seminal chamber lying near base of a prominent excavation, the latter carrying an evident hairy pulvillus; en often but not alwayswith a strong mesal process (s), either slenderer and simple or larger and more complex in shape, as well as usually with a distinct, often again branching, laterobasal outgrowth (p); distal remainder of en elongate, often branching and enlarged, sometimes fringed with short setae or spines.
Remarks.
This species seems to be the most widespread and variable among congeners. It has heretofore been accepted as being split into two nominal subspecies: Epanerchodus orientalis orientalis and Epanerchodus orientalis takakuwai Verhoeff, 1913, but, given a similarly profound variation range in body size and shape, and, especially, in gonopod structure as observed in Japan alone, the subspecific status of takakuwai has long been questioned (e.g. Miyosi 1959, Murakami 1969, Nishikawa and Murakami 1993). Murakami (1993), in the latest checklist of the Japanese Diplopoda, treats Epanerchodus orientalis without subspecies. Moreover, numerous samples from Hokkaido, Honshu and Shikoku, Japan, reveal that variation in gonopod conformation appears to be purely individual, failing to demonstrate any meaningful geographical patterns ( Nishikawa and Murakami 1993). The same concerns the available samples from Taiwan. So we formalize here the long suspected synonymy: Epanerchodus orientalis orientalis Attems, 1901 = Epanerchodus orientalis takakuwai Verhoeff, 1913, syn. n.
It is noteworthy that, formally, Epanerchodus orientalis fails to occur in southernmost Japan, i.e. on Kyushu Island and in the Ryukyus ( Nishikawa and Murakami 1993, Nakamura and Korsós 2010), to reappear further south only in Taiwan. In northern Honshu, Japan, it is known to reach 26 mm in length and 3.4 mm in width, with the collum being slightly broader than the head ( Murakami 1969). In Taiwan, as proven by our study of several abundant syntopic samples, the animals tend to be smaller, the collum is invariably narrower than the head, while rather often the gonopods are totally devoid of both an exomere remnant and process s, frequently with the distal, longest part of their endomere being slender, not expanded.
Looking at such a profound variation as observed in a number of peripheral and gonopod characters in Epanerchodus orientalis , one cannot ignore several further nominal congeners described from Japan, including Kyushu, in which the gonopods look especially similar to those of Epanerchodus orientalis : Epanerchodus inferus Verhoeff, 1941, Epanerchodus lobatus Verhoeff, 1941, Epanerchodus satoi Takakuwa, 1954, Epanerchodus tenuis Takakuwa, 1954, Epanerchodus aculeatus Miyosi, 1954, Epanerchodus etoi Miyosi, 1955, Epanerchodus chichibensis Haga, in Takashima and Haga 1956, Epanerchodus yoshidai Haga, in Takashima and Haga 1956, Epanerchodus lacteus Shinohara, 1958, etc. (e.g. Takashima and Haga 1956, Shinohara 1958, Miyosi 1959). We suspect that some of them might well prove to represent junior synonyms of Epanerchodus orientalis . Only future in-depth biological observations and such genetic investigations as bar-coding of such particularly similar forms can shed light on their true identities and statuses, because polymorphic variation has long been known in Epanerchodus . Thus, Epanerchodus polymorphus Mikhaljova & Golovatch, 1981, widespread in the southern part of the Russian Far East and in northern Korea, shows two morphologically distinct morphs both in gonopod and peripheral structure in males, but a complete, overlapping range of the same somatic characters in females. Both male morphs invariably co-occur syntopically and either mates with any female variety ( Mikhaljova and Golovatch 1981, Mikhaljova 2004). A similar situation is found in the nominate species Epanerchodus acuticlivus Murakami, 1970 and Epanerchodus aster Murakami, 1970, both described from the same cave in Shikoku, Japan. Murakami (1970) explicitly admitted that they were very close, with their females being indistinguishable, while the males showed small but stable differences in gonopod telopodite armature.
Based on the great variation observed in the populations of Epanerchodus orientalis in Japan and, especially, Taiwan, the statuses of Epanerchodus polymorphus , Epanerchodus acuticlivus and Epanerchodus aster as further congeners highly similar to Epanerchodus orientalis are likewise to be questioned, as at least some of them might also prove to be the latter’s junior synonyms. Yet no formal synonymies are advanced here as obviously being too premature at this purely descriptive taxonomic stage.
That not all of the congeners similar in gonopod structure to Epanerchodus orientalis are synonyms of the latter is proven at least by Epanerchodus koreanus Verhoeff, 1937, a species common throughout Korea, in Kyushu, Japan and in the southern Russian Far East. At least in Russia, it often occurs syntopically together with Epanerchodus polymorphus . Yet Epanerchodus koreanus , despite its minor variations in gonopod conformation, is easily recognizable even superficially through its much wider paraterga (3.3-3.8 versus 2.6-3.0 mm); in addition, these species never mate ( Mikhaljova 2004). As another proof to the above statement may also serve Epanerchodus pinguis sp. n., described below and representing still one more congener quite similar in gonopod structure to Epanerchodus orientalis . In Taiwan, both are at least partly sympatric, but Epanerchodus pinguis sp. n. differs markedly enough in a number of peripheral and gonopod characters to warrant recognition of a distinct species (see below).
In other words, several, but definitely not all, of the nominate species of Epanerchodus that show their gonopods particularly similar in structure to those of Epanerchodus orientalis are jeopardized as potential junior synonyms of the latter species.
In Taiwan, Epanerchodus orientalis occurs in various habitats ranging from lowlands to the mid-montane belt (up to 1,250 m a.s.l.) all over the island (Map 2).
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