Cladolasma ailaoshan, a new species of the genus Cladolasma Suzuki, 1963 from China (Opiliones, Nemastomatidae, Ortholasmatinae)

Abstract The fourth species of the Asian genus Cladolasma, C. ailaoshan sp. n. is described from specimens collected in Yunnan Province, China. The new species is distinct from C. parvulum Suzuki, 1963 and C. angka (Schwendinger & Gruber, 1992) in lacking enlarged, dorsally-directed tubercles on the abdominal scutum; and from C. damingshan Zhang & Zhang, 2013 in having keels around the eyes and in the position of the eyes. Differences in male genital structures between the Chinese species are small, while there are more differences with the Japanese species.

During biodiversity surveys, intensive collections were made at Ailaoshan National Natural Reserve in August 2011 by the personnel of the Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences. Among the collected specimens, a new species, C. ailaoshan sp. n. is recognized and described below. This constitutes the second species of the genus recorded from China.
Paratype. 1♀ (MHBU-Opi-20160423), same data as the holotype. Etymology. The species epithet is a noun in apposition referring to the type locality. Description of the male holotype. Habitus as in Figs 1, 5, 19. Coloration in alcohol: dorsum yellowish brown (Fig. 19). Propeltidium with much darker brown areas. Eye rings black, hood pale tan (Fig. 21). Meso-and metapeltidium yellowish brown. Most of the opisthosomal scutum brown, only areas IV-V yellowish brown posteriorly. Venter dark brown, slightly lighter in ventral centre (Fig. 20). Chelicerae chestnut brown. Pedipalpi pale brown except for dark brown trochanters, tibiae and tarsi. Legs yellowish brown except for dark brown trochanters, metatarsi and tarsi.
Dorsum (Figs 5,19). Entire body strongly sclerotized. Metapeltidium clearly separated from carapace and abdominal scutum (Figs 5,19). Free tergites not visible from above. Surface covered with network of interconnected anvil-shaped tubercles. Anterior border of carapace with one lateral hood process on each side of ocularium. Metapeltidium with a transverse row of anvil-shaped tubercles (Figs 5,19). Abdominal scutum with intricate lattice of interconnected anvil-shaped tubercles, its posterior margin with fence-like row of seven enlarged, posteriorly-directed digitiform tubercles. Free tergites on caudal surface of body with low keels in transverse rows (Figs 1, 20).
Hood (Figs 1, 5, 21) elevated above dorsal surface of body, arched, with one median, unpaired and 4 lateral, paired digitiform tubercles, diminishing in length toward base of hood; these digitiform tubercles usually with small basal cross-bars. Basal pair of digitiform tubercles connected at their base to circumocular keels touching each other above the eyes forming a short irregular median keel, the latter distally splitting into two branches.
Venter (Fig. 20). Coxae with dense wart-bearing setae on ventral surfaces and with dorso-distal rows of anvil-shaped tubercles; a row of anvil-shaped tubercles along anterior and posterior margins of coxae II, III and IV; coxae I and II with distal digitiform processes retro-laterally; coxa IV with similar process pro-laterally. Genital operculum short, almost tongue-shaped, surface with tubercles. Sternites with transverse rows of low keels, these reduced in the midline.
Chelicerae (Figs 2-4). Basal segment with a low dorso-medial tubercle, without glandular area, only ventrally and dorsally with a few setae. The basal end of second segment spherical, and with one basal pro-dorsal tooth (Fig. 2). Many long dorsal setae, and rows of short setae at base of fixed finger (Fig. 2). Fingers short, with diaphanous teeth and dark subapical teeth: one dark tooth on movable finger, two dark teeth on fixed finger (Fig. 4). Pedipalpi (Figs 6-7). Trochanters with two ventral setiferous tubercles. Femora with few clavate hairs. Patellae medially with many clavate hairs and laterally with few clavate hairs. Tibiae and tarsi densely covered with clavate hairs.
Penis (Figs 13-18) slender and lanceolate; no clear distinction between shaft, glans, and stylus. Shaft nearly parallel-sided, widened basally, then tapering distally (seen from ventral); in proximal portion dorso-ventrally depressed, in median portion elliptical and wider than long in cross-section, in distal portion close to glans almost circular in cross-section. Base of truncus dorsally bent almost at 90° together with two large lobe-like roots (seen from lateral). Glans bulged ventrally and dorsally (lateral view, Fig. 14); distal part of glans with six small spines at the base of the stylus and basal part with two small ventral and two small dorsal spines, and two large lateral spines (Figs 15-18). Stylus simple, slender, slightly torsion; tip of stylus bent.
Distribution. Known only from the type locality, the Ailaoshan National Natural Reserve in Yunnan Province, China.
Remarks. After the genus Cladolasma was reinstated for the Asian species C. parvulum from Japan and C. angka from northern Thailand, one additional species was found, i.e., C. damingshan Zhang & Zhang, 2013 from subtropical southern China and in addition, the present C. ailaoshan sp. n., also from a subtropical environment. These specimens reinforce the distinctive characters between Cladolasma (Asiatic Ortholasmatinae) and Dendrolasma (American Ortholasmatinae) in morphological characters, e.g., metapeltidium in Cladolasma separated from abdominal scutum, while it is fused to it in Dendrolasma; Cladolasma with a relatively stout penis shaft, a compressed glans and a short, slender, pointed stylus, whereas Dendrolasma has a long, thinner shaft, a flattened glans and a contorted stylus.
According to the male genitalia of Cladolasma (penis unknown in C. angka), C. ailaoshan sp. n. and C. damingshan are clearly different from C. parvulum. The penial glans has a pair of large spines laterally in the new species and C. damingshan, while the glans has a lateral row of large spines in C. parvulum. Consequently, the penis of the new species shows closer relationship to C. damingshan than to C. parvulum.
The spination of glans penis follows the same pattern in the two Chinese species presently known (C. ailaoshan sp. n. and C. damingshan): the spines at the base of the stylus are arranged in a verticillate order (Figs 15-16; only small spines in damingshan; Zhang and Zhang 2013: 449, figs 22-24, larger ones in C. ailaoshan sp. n. sp.), the lateral spines are more distantly positioned from the base of stylus than in C. damingshan, and the two dorsal and two ventral spines are located between these two groups of spines. Additionally, the two Chinese species are different in the number of verticillate spines (six spines in C. ailaoshan sp. n., eight in C. damingshan) and by the size of the spines (small dorsal and ventral spines in C. ailaoshan sp. n., large ones in C. damingshan).
Moreover, C. ailaoshan sp. n. can be easily distinguished from C. damingshan by the slender and curved stylus, the shape of the dorso-basal tooth on the second segment of male chelicerae, the keels around the eyes, and the location of the eyes on the hood.