Suthepia inermis, Martens, 2020

Martens, Jochen, 2020, A mysterious dwarf: Suthepiidae nov. fam., a new harvestman family from mountains of northern Thailand (Arachnida: Opiliones: Laniatores), Revue suisse de Zoologie 127 (2), pp. 381-391 : 383-388

Suthepia inermis sp. nov.

Figs 1-44

Holotype: SMF; male; THAILAND, Chiang Mai Province and District, Doi Suthep , 1300 m; J. Trautner and K. Geigenmüller leg.; 26.I.1989.

Paratypes: SMF; 1 female; collected together with the holotype . – MHNG; 1 male, 1 female; Chiang Mai Province, Chomthong District, Doi Inthanon , 1080 m; 24.II.1987 . – MHNG; 2 females; Doi Inthanon, Pha Mon Valley , 910 m; 23.II.1987 . – MHNG; 1 female; Chiang Mai District, Doi Suthep , 1150 m; 14.II.1987 . – MHNG; 2 males, 2 females; Doi Suthep , 750 m, 17.X.1990. – MHNG; 1 female; Doi Suthep , 1090 m, 2.XII.1985 . – MHNG; 10 males, 10 females ; CJM; 2 males, 1 female; Doi Suthep, below Tham Rüsie (18°48’18”N 98°55’02”E), 1090 m, evergreen hill forest; 13.I.2011; sample THMY-10/10 . – MHNG; 2 males, Chiang Mai Province, Chiang Dao District, Doi Chiang Dao , 840 m; 21.II.1986 . – MHNG; 2 males, 4 females; Doi Chiang Dao , 450 m, 7.III.1987. – MHNG; 1 female; Doi Chiang Dao , 510 m; 22.IX.-25.X.1990 (in pitfall traps) . – MHNG; 3 males, 2 females; Chiang Mai Province, Mae Taeng District, Huay Nam Dang , 1400 m; 17.XII.1990. All MHNG specimens leg. P.J. Schwendinger.

Diagnosis: A small species with a rather pyriform body, its dorsal side without tubercles or spines, with smooth surface; Tu oc low, broader than long, rounded. Chelicera strong, proximal article massively inflated in distal half. All articles of male pedipalp set with scattered setae, without apophyses and without spines; tarsus compressed and dorso-ventrally extended, with two rounded apophyses distally and dorso-distally, a smaller and a larger one, tarsal claw weak, not longer or stronger that longest apical seta. Female pedipalp generally as in male, but tarsus not enlarged and compressed, without apophyses, carrying a stronger claw.

Name: The Latin adjective “inermis” means without weapons and refers to the largely unarmed body of males and females, devoid of tubercles, spines and large sensilla.

Description: MALE. Body, dorsal side ( Figs 1 , 5 ): Dark brown, without any light markings, pyriform (in dorsal view), prosomal part of dorsal scutum narrower than opisthosomal part, the latter continuously enlarged, broadest in proximal part. Fused opisthosomal tergites I-V without sulci. Free opisthosomal tergites I-III visible from above. Anterior margin of dorsal scutum with a small pointed projection; Tu oc low, dorsally rounded, separated from anterior margin of dorsal scutum by half its length; eyes small, with black surrounding ring. A row of minute tubercles on posterior margin of free opisthosomal tergite III; no strong setae; otherwise surface smooth but not shiny.

Body, ventral side ( Fig. 6 ): On Cx I-II two relatively large elongate tubercles dorso-laterally; a row of minute tubercles on last free tergite and on Op anale. Op gen ( Fig. 6 ) broader than long, slightly enlarged posteriorly, horizontally divided into a slim movable anterior part and a much larger immovable posterior part. Op gen continuous with the stigmatic segment.

Chelicera ( Figs 37-38 ): Basal article with a massive dorsal boss in distal half, its posterior margin drawn out and covering parts of posterior half of article and additionally covering a narrow anterior part of dorsal scutum in front of Tu oc; dorsal boss of basal article posteriorly ending in a pair of blunt Apo. Ventral side of basal article with a field of minute Tu ventrally. Second article slender frontally and ventrally, set with setae of various lengths, the longest ones close to base of distal article.

Pedipalp ( Figs 9-12 ): Rather stout; Tr bulged dorsally, with one short seta, a longer one ventrally; Fe slightly curved ventrally, broadest in distal two thirds, with three minute setae dorsally, one ventro-basally (in lateral/ medial views); Pt with slender basis, enlarged distally; Ti quite massive, widening from basis to distal end, there slightly constricted to insertion of Ta; Ta markedly enlarged dorso-ventrally and markedly compressed, forming a paddle-shaped plate, dorso-distally with a large blunt Apo carrying two large setae (one on inner side, one on outer side, these slightly longer than tarsal claw) and distally with a smaller blunt Apo without setae; a rich setation on dorsal and inner side, less so on ventral and outer side; tarsal claw remarkably slender, markedly arched only in distal half. All setae and claw hyaline, not strongly sclerotized, strongest seta longer than and almost as strong as claw.

Legs ( Figs 17-20, 25-28 ): Short, all articles with circular cross section, nearly unarmed except for few minute setae on low Tu mainly on ventral side of Fe I and III-IV ( Figs 17-20 ); Fe ( Fig. 19 ) and less so Pt and Ti of leg III markedly swollen; distalmost tarsal article of leg I and III slightly enlarged; a single unpectinate claw on Ta I-II (see Fig. 43 showing female), an unpectinate double claw on Ta III-IV (see Fig. 44 showing female).

Genital morphology ( Figs 33-36 ): Penis highly complex, with complicated expandable and eversible parts, short and compact. A slight constriction above a broad base, then continuously widening and again becoming slightly constricted (in dorsal/ventral views), narrowest at about half-length of entire penis, then massively broadened, i.e. enlarged laterally and dorso-ventrally, forming a largely symmetrical, mushroom-like structure. Basal part of penis in la view similar to it in dorsal/ventral view but more bulged on ventral side. Distal half of penis with two large rounded plates protruding ventrally and causing an asymmetrical shape ( Fig. 34 ). Distal part of penis highly complex and prone to unfolding by hemolymph pressure. Penis setation: Two groups of two and three slightly curved latero-distal setae pointing distad, two single short and strong setae flanking ventral plates laterally ( Figs 34- 36 ), two setae in distant position on dorsal side near basis of broadening of distal portion of penis ( Fig. 33 ).

Discernible inner structures: An elongate prickly funnel in centre of broad distal part of penis with numerous denticles pointing distad, funnel apparently opening to centre of distal surface. Further inner structure containing seminal duct inside prickly funnel ending in distal stylus, its opening slightly below distal opening of funnel (in resting position). One pair of short tubular structures, each with rounded end at surface of penis, situated lateral to opening of funnel ( Figs 33-34 ).

FEMALE: Similar to male in general habitus ( Figs 4, 7-8 ), hardly any differences in chelicerae ( Figs 39-40 ); Op gen smaller than in male, not horizontally divided into two parts, more rounded and nearly circular ( Fig. 8 ). Pedipalpal Ta ( Figs 13-16 ) markedly different from that of male, tapering from basis to distal end, cone-like, not compressed, with few short setae on all sides, longest at basis of claw; claw stronger and more compact than in male, slightly curved. Legs ( Figs 21-24, 29-32 ) nearly identical to those of male in length and armature, only Fe III ( Fig. 23 ) less inflated than in male. Pt and Ti of leg III not swollen, distalmost tarsal article of leg I only slightly swollen ( Fig. 29 ), Fe I-IV ventrally with a few low Tu, most pronounced on Fe I and II ( Figs 21-22 ).

Genital morphology ( Figs 41-42 ): Ovipositor short, with two rounded distal lobes on right and left side; on each lobe three long setae crossing each other; all setae confined to dorsal side.

Measurements: Body length of males: 1.6-1.7 (n=11), of females: 1.55-1.8 (n=9). Pedipalp length of males (females in parentheses): Tr 0.15 (0.2), Fe 0.25 (0.25), Pt 0.2 (0.15), Ti 0.18 (0.18), Ta 0.3 (0.2). Penis length 0.7.

Leg articles of males and females: See Table 1 .

Variation: Very little. Body size, body and leg armature and male pedipalp morphology of the 44 specimens examined largely invariable.

Distribution and ecology: The altitudinal distribution of this species ranges from 450 m to 1400 m and all collecting sites are in forested areas, mostly primeval, also near forest edges. Few specimens were collected by hand, all others were sieved from forest litter. The collecting months are I, II, III and X, XII; all in the pre-or post-monsoon season when collecting (especially sieving) is easier due to reduced precipitation. Apparently this species is eurychronous.

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The localities at only 450 m and 510 m altitude at the foot of the Doi Chiang Dao are exceptional from an ecological point of view. These are one of the few stands of evergreen forest in the lowlands of northern Thailand. In that seasonally dry region this forest type is usually found only above 1000 m. Apparently the rainwater which drains underground from the limestone slopes of Doi Chiang Dao (2175 m) resurfaces at the foot of the mountain and causes humid conditions all year round which in turn sustain an evergreen forest (P.J. Schwendinger, personal communication).

Figures

Figs 1-2. Suthepia inermis sp. nov., body in dorsal view.(1) Female paratype. (2) Male holotype. Scale line 0.5 mm. Photograph by J. Severin.

Figs 3-8. Suthepia inermis sp. nov, male holotype (3, 5-6), female paratype. (4, 7-8). (3-4) Habitus, lateral view. (5, 7) Habitus, dorsal view, (6, 8) Habitus, ventral view. Scale line 0.5 mm.

Figs 9-16. Suthepia inermis sp. nov., pedipalps of male holotype (9-12) and of female paratype (13-16). (9, 13) Right pedipalp, retrolateral view. (10, 14) Same, prolateral view. (11, 15) Right pedipalpal tarsus, retrolateral view. (12, 16) Same, prolateral view. Scale lines 0.3 mm.

Figs 17-32. Suthepia inermis sp. nov., male paratype (17-20, 25-28), female paratype (21-24, 29-32). (17-24) Femora I-IV, retrolateral view. (25-32) Tarsi I-IV, retrolateral view. Scale lines 0.3 mm.

Figs 33-44. Suthepia inermis sp. nov., male holotype (33-38), female paratype (39-44). (33) Penis in dorsal view. (34) Same in ventral view. (35-36) Same in lateral view. (37, 39) Right chelicera, prolateral view. (38, 40) Same in retrolateral view. (41) Whole ovipositor, ventral view. (42) Distal part of ovipositor, ventral view. (43-44). (43) Single claw of leg I of female, retrolateral view. (44) Double claw of leg IV of female, retrolateral view. Scale lines: 0.3 mm (33-36; 37-41), 0.05 mm (42), 0.07 mm (43-44).

Tables

Table 1: Leg articles of males (females in parentheses

	Tr	Fe	Pt	Ti	Mt	Ta	Total
I	0.2 (0.25)	0.6 (0.55)	0.2 (0.2)	0.4 (0.45)	0.65 (0.7)	0.6 (0.6)	2.65 (2.75)
II	0.25 (0.25)	0.8 (0.8)	0.35 (0.3)	0.8 (0.7)	0.9 (0.9)	1.05 (1.05)	4.15 (4.0)
III	0.25 (0.2)	0.6 (0.6)	0.25 (0.25)	0.45 (0.4)	0.5 (0.6)	0.6 (0.5)	2.60 (2.55)
IV	0.3 (0.25)	0.8 (0.8)	0.25 (0.3)	0.65 (0.7)	0.9 (0.9)	0.9 (0.95)	3.85 (3.9)