Asiolasma, Martens, 2019

Martens, Jochen, 2019, An ancient radiation: Ortholasmatine harvestmen in Asia - a new genus, three new species and a revision of the known species (Arachnida, Opiliones, Nemastomatidae), Revue suisse de Zoologie 126 (1), pp. 79-110 : 83-86

Genus Asiolasma gen. nov.

Type species: Dendrolasma angka Schwendinger & Gruber, 1992 .

Diagnosis: Asian Ortholasmatinae with free metapeltidium not joined to prosoma or to opisthosoma. Characterized by an unspecialized penis with a rather short, slightly twisted stylus, opening of seminal duct sub-terminal; spicules on apex of penis rather long on do, ve and la sides of glans (rarely on distal part of truncus), in most cases symmetrically arranged in three (rarely four) groups on glans and on distal part of truncus, rather uniform in all known species; network of anvil-shaped denticles on do side of body present, cells not strongly symmetrical, appearing somewhat disorderly, individual cell-forming denticles low in most species, thus without marked sculpture on opisthosomal scutum.

Name: It is derived from Asia, the continent where the species of this genus live, and the Greek noun “elasma”, a plate, mainly of metal, referring to the hood on the anterior margin of the prosoma. The name is in analogy of the other generic names of Ortholasmatinae . The gender of the name is neuter.

Distribution ( Fig. 1 ): The six hitherto known species occur in northern Thailand (Doi Inthanon), northern Vietnam, as well as southwestern and southern China (Yunnan, Guangxi and Gansu provinces, respectively). The few available records are highly scattered and span a geographically and climatically large and diverse area from the tropics/subtropics in Vietnam, southern China and northern Thailand to high altitudes of temperate mountain ranges in central southwestern and partly southern China. According to current knowledge, Asiolasma species are confined to mountainous areas between 1200 m and 3300 m in China, 900 m in northern Vietnam, 2400-2500 m in northern Thailand, and the sole Cladolasma species has been recorded at 1200-1500 m on Shikoku Island, Japan.

Relationships: Judging from male genital morphology and formation of the hood, all Asiolasma gen. nov. species known at present seem to be closely related with each other. These characters seem to be rather uniform, although differences between species are present. Specific distinctions are also found in body shape, body size, equipment of body with a lattice work of anvil-shaped tubercles, size and shape of pedipalps and pattern of setae on pedipalpal articles, presence or absence of pedipalpal glands and shape of apophyses on chelicerae. These need to be carefully identified. The Asiolasma gen. nov. species can be divided into two groups. Three of the southern species display only a pointed hook on the upper side of the 2nd cheliceral article ( A. angka [ Fig. 27 ], A. damingshan [ Fig. 35 ], A. schwendingeri sp. nov. [ Fig. 100 ]; in the single northern species ( A. billsheari sp. nov. [ Fig. 112 ] and in two of the southern species this hook is present as well but situated on a massive rounded apophysis ( A. juergengruberi sp. nov. [ Figs 72-74 ], A. ailaoshan [ Figs 55-56 ]). The Japanese Cladolasma parvulum stands apart and differs markedly in genital morphology, in a little developed do network of anvil-shaped tubercles and in a small anterior hood (see above).

All species of the American ortholasmatine genera Ortholasma Banks, 1894a , Dendrolasma Banks, 1894b , Trilasma Goodnight & Goodnight, 1942 , Martensolasma Shear, 2006 and Cryptolasma Cruz-López, Cruz-Bonilla & Francke, 2018 clearly differ from Asian species by the following characters: i) the penis is much more slender, the inflated base shorter, the stylus formed like a barbed hook (not so in Dendrolasma ), the armature of the glans is more diversified and the spicules often of different size and pattern (uniform in Ortholasma ); ii) many (up to twelve on each side) apophyses are present on the hood, the single distal and all following lateral apophyses of the hood are interconnected by fine bridges only at the distal end of the apophyses (hood lacking in Martensolasma ); iii) the network of closed keel cells formed by anvilshaped tubercles on the do scutum is regular, distinctly symmetrical and ornamental, the individual tubercles markedly elevated, resulting in a distinct and elaborate structure of the network (for all characters compare multiple details in Shear & Gruber, 1983 and Shear, 2010).

Figures

Fig. 1. Distributional records of ortholasmatine species in East and Southeast Asia. (1) Asiolasma billsheari sp. nov., China, Gansu, Qinling range. (2) A. juergengruberi sp. nov., China, Yunnan, above Lugu Hu. (3) Same species as before, China, north of Lijiang. (4) A. ailaoshan, China, Yunnan, Ailao Shan. (5) A. damingshan, China, Guangxi, Daming Shan. (6) A. schwendingeri sp. nov., Vietnam, Mt Ba Vi. (7) A. angka, Thailand, Doi Inthanon. (8) Dendrolasma parvulum, Japan, Shikoku Island.

Figs 27-30. Asiolasma angka, male (27, 29), female (28, 30). (27-28) Right chelicera in prolateral view. (29-30) Right pedipalp in prolateral view. Scales: 1.2 mm (27-28); 0.3 mm (29-30).

Figs 33-37. Asiolasma damingshan, male holotype. (33) Body in dorsal view. (34) Same in lateral view. (35) Chelicera in prolateral view. (36) Apophsis of 2nd cheliceral article in prolateral view. (37) Left pedipalp in retrolateral view. Figs 33-34 reproduced from Zhang & Zhang (2013). Scales: 0.03 mm (36); 0.2 mm (35); 0.4 (37); 0.5 mm (33-34).

Figs 94-103. Asiolasma schwendingeri sp. nov., male holotype (94-100, 102), female paratype (101, 103). (94) Glans penis in lateral view. (95) Same in ventral view. (96) Same in dorsal view. (97) Whole penis in lateral view. (98) Same in ventral view. (99) Same in dorsal view. (100-101) Right chelicera in prolateral view. (102-103) Right pedipalp in prolateral view. Scales: 0.1 mm (94-96); 0.3 mm (100-101); 0.25 mm (97-99); 0.5 mm (102-103).

Figs 112-117. Asiolasma billsheari sp. nov., male holotype. (112) Right chelicera in prolateral view. (113) Same in retrolateral view. (114) Apophysis of 2nd cheliceral article in prolateral view. (115) Pedipalp in prolateral view. (116) Distal part of pedipalpal femur, whole patella and proximal part of tibia in retrolateral view. (117) Apophysis on ventro-distal part of pedipalpal patella in prolateral view. Scales: 0.1 mm (114); 0.2 mm (112-113); 0.3 mm (115-116); no scale (117).

Figs 72-77. Asiolasma juergengruberi sp. nov.; male (72-75, 77), female (76). (72, 74, 76) Right chelicera in prolateral view. (73, 75) Same in retrolateral view. (77) Apophysis of 1st cheliceral article. (72-73, 76-77) specimen from Lugu Hu. (74-75) specimen from Lijiang. Scale: 0.3 mm (72-76); no scale (77).

Figs 55-59. Asiolasma ailaoshan, male(55-56, 58), female (57, 59). (55, 57) Right chelicera in prolateral view. (56) Same in retrolateral view. (58-59) Left pedipalp in prolateral view. Scale: 0.3 mm.