Wednesday, June 2, 2021

[Arachnida • 2020] Suthepia inermisA Mysterious Dwarf: Suthepiidae nov. fam., A New Harvestman Family (Opiliones: Laniatores) from Mountains of northern Thailand

Suthepia inermis 
Martens. 2020

A new family of laniatorean harvestmen from northern Thailand is proposed, Suthepiidae fam. nov., which comprises one new genus and one new species, Suthepia inermis sp. nov. This family stands out by characters hitherto unknown or rarely recorded for Opiliones, and close relatives of this taxon are presently not discernible. Important characters are a short and compact penis with a massively enlarged distal part with a rich armament of sclerites and membranes which can be moved and everted by hemolymph pressure during mating; the pedipalp of males and females is without raptorial adaptations, i.e. elevated sockets (= apophyses) carrying strong distal spines are completely absent, therefore no prey capture basket is present; the male pedipalpal tarsus is enlarged and compressed, its dorso-distal double apophysis presumably contains a gland; the pedipalpal claw is weak, not longer or stronger than long hyaline setae on the dorso-distal apophysis of the tarsus. The only specimens presently known were found in litter of a few forested mountain stocks, between 450 m and 1400 m altitude. A brief overview of Southeast Asian laniatorean families is presented.

KEYWORDS: Supra-generic systematics, genital morphology, new genus, new species, Southeast Asia

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.

Suborder Laniatores Thorell, 1876
Infraorder Grassatores Kury, 2003

Family Suthepiidae fam. nov.
Type genus: Suthepia gen. nov.
Included genera: Presently only one, the type genus.

Diagnosis: A family of the order Opiliones, suborder Laniatores, infraorder Grassatores with the following characters: Small species with less than two mm body length. Body surface of males and females rather smooth, without conspicuous tubercles, thorns or setae. Penis stout, distal half strongly enlarged laterally and dorso-ventrally, with complex hemolymph-pressure-driven system of sclerites and membranes, with an eversible prickly funnel in its interior, and with pairs of single setae plus pairs of groups of setae. Ovipositor short, with three pairs of long sub-apical setae on ventral side. Pedipalp in males and females smooth, without any apophyses carrying setae (i.e. not the raptorial type of laniatorean pedipalps); tarsus of males enlarged, bilaterally compressed, with scattered distal setae slightly longer than and as strong as tarsal claw.

Distribution: Presently only one species is known from mountains in northern Thailand.

Relationships: Suthepiidae is unique in possessing several presumably apomorphic characters of the male and female pedipalp (non-raptorial type of pedipalps) and in its male and female genital morphology (stout, distally markedly enlarged penis with a complex eversible system including a prickly funnel; ovipositor with three pairs of slender sub-apical setae only on ventral side). Currently no close relationships to any extant Southeast Asian laniatorean family is discernible (see Discussion).

Suthepia gen. nov.
Type species: Suthepia inermis sp. nov. by monotypy and designation.

Included species: Only the type species.

Diagnosis: As given for the family Suthepiidae: Pedipalps not forming a catching basket, completely devoid of any apophyses carrying spines in both sexes; pedipalpal tarsus in males compressed and deepened, with apical setae more or less as long and strong as tarsal claw. Male genital morphology highly complex, with a complicated set of sclerites and membranes, with an eversible prickly funnel and with a complex arrangement of single setae and small groups of setae. Body largely unarmed, no conspicuous apophyses, thorns, granules or setae present. Small species with a body length of less than 2 mm.

Name: The Latinized generic name refers to one of the localities of the type material, the Doi Suthep, a mountain in northern Thailand. The gender is female.

Distribution: Currently known from four mountains of northern Thailand

Suthepia inermis sp. nov.
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.

Jochen Martens. 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); 381-391. DOI: 10.35929/RSZ.0028