Lipistius malayanus
Creators: name: Peter J. Schwendinger
Publisher: name: Zenodo
Year: 2017
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Arachnida
Araneae
Liphistiidae
Lipistius
Lipistius malayanus

description: The malayanus -group
Diagnosis: Distinguished from the trang -group by an indistinctly split embolus proper (Fig. 3B, D, F, H) and from all other species groups by distal edge of contrategulum proventrally ending in a V-shaped or U-shaped row of denticles (the clearest synapomorphy of this group; Figs 4C; 6A, C; 8A, D). Vulval plate strongly sclerotised, with a large, undivided CDO and with a large, undivided receptacular cluster (Figs 5, 7, 9).
Description: Small to large species (carapace length of males 4.36-12.04, carapace width 3.64-10.99); body colouration uniformly dark (in large species: L. malayanus and L. endau; Fig. 2A) or brown with annulated legs and palps (in smaller species: L. johore and L. gracilis sp. nov.). Male palp with membranous and sclerotised part of embolus proper in close contact with each other (both distinctly separated in trang - group), together forming a closed tube; dorsal wall of sclerotized part of embolus proper straight and directed proventrad (L. malayanus; Fig. 4 G-H), curved prodorsad (L. endau; Fig. 6F, H) or bent prodosad (L. gracilis sp. nov.; Fig. 8 F-G); para-embolic plate short or absent (Figs 4D, 6E); tegulum with coarsely dentate proximal edge (corresponding to dorsal extension of terminal apophysis in Heptathelinae; see Schwendinger & Ono, 2011), distal margin (corresponding to marginal apophysis) indistinct, not drawn into a prominent edge (Figs 4 D-F, 6D-E, 8E); contrategulum with indistinct ventral process or without, distal edge carrying several teeth, prolateral ones numerous, tiny and forming a serrate crest (L. gracilis sp. nov.; Fig. 8 D-G), few and small (L. malayanus; Fig. 4 G-L), or only represented by a single large triangular tooth (L. endau; Fig. 6F, H-O), proventral denticles of distal edge forming a downwardcurved V-shaped (Fig. 4C) or U-shaped row (Figs 6A, C; 8D), dorsal apex of contrategulum widely to narrowly tongue-shaped (Figs 4 G-L; 6F, H-O; 8F-G); subtegulum always without apophysis; paracymbium quite small and shallow to large and deep (Figs 4A, 6B, 8B); cumulus very low, indistinct, carrying several long, thick bristles; retrolateral tibial apophysis relatively short and carrying long apical megaspines (L. malayanus and L. endau; Figs 4 A-B, 6A-B) or quite long and carrying distinctly shorter megaspines (L. gracilis sp. nov.; Fig. 8 A-C, I-J); both apical lobes of cymbium weakly developed (Fig. 8D). Vulva (Figs 5, 7, 9, 10A): poreplate strongly pigmented and sclerotised, wider than long, its anterior margin more or less distinctly recurved, with or without anterolateral lobes or processes, never with mediolateral processes; CDO and ventral receptacular cluster large to very large, both undivided; posterior stalk wide (in L. endau even covering entire width of genital atrium; Fig. 7), somewhat trapezium-shaped or almost triangular (Fig. 10A); genital atrium with few to many lateral hairs and with no, few or numerous median hairs.
Species included: Liphistius endau, L. malayanus, L. gracilis sp. nov. and presumably also L. johore (male still unknown).
Relationships: Species of the malayanus -group are most similar and probably closely related to species of the tioman -group. The two large species, L. malayanus and L. endau, are closer to each other than to the much smaller L. gracilis sp. nov. (distinguished by serrate distal edge of contrategulum and by sharp bend in wide dorsal wall of sclerotised part of embolus proper). Small size, details of the vulval plate and geographical proximity suggest a close relationship between L. gracilis sp. nov. and L. johore, but this can only be confirmed when the male of the latter species is discovered.
Key to the species of the malayanus -group:
1 Small spiders (carapace length of mature males and females 4.36-5.34, carapace width 3.64-4.22) with brown body colouration and annulated limbs; lateral and posterolateral margins on ventral side of poreplate not bulging (Fig. 9B, D, F; Platnick & Sedgwick, 1984: fig. 80).........................................................................................................2
- Large (carapace lengths in males 7.90-12.04, carapace width 7.0-10.99), uniformly dark-coloured spiders; lateral and posterolateral margins of poreplate on ventral side of vulval plate bulging (Figs 5B, J; 7B, E, G)..................3
2 Vulval plate with indistinct transition between poreplate and posterior stalk, the latter wide in transition zone; anterior margin of poreplate without or with only indistinct anterolateral invaginations; genital atrium with numerous lateral and median hairs (Fig. 9A, C, E) ...................................................................... L. gracilis sp. nov.
- Vulval plate with distinct transition between poreplate and posterior stalk, the latter very narrow in transition zone; anterior margin of poreplate with pronounced anterolateral invaginations; genital atrium without hairs (Fig. 10A) (male unknown) ........................................................................................................................................... L. johore
3 Dorsal and ventral wall of sclerotised part of embolus proper equally wide, both ends facing proventrad (Fig. 4 G- H), dorsal wall ending in indistinct rounded lobe (Fig. 4 C-F); membranous part of embolus proper distally narrow (Figs 3F, H; 4C); distal edge of contrategulum with one to several small denticles (Fig. 4C, G-L); paracymbium about as deep as wide (Fig. 4A). Dorsal side of vulval plate with anterolateral corners of genital atrium not bulged and elevated above level of poreplate; usually no median hairs in genital atrium (Fig. 5A, C-H, but see Fig. 5I); receptacular cluster not divided into subclusters (Fig. 5B, J)............................................................... L. malayanus
- Dorsal wall of sclerotised part of embolus proper wider than ventral wall, end of dorsal wall bent prodorsad (Fig. 6F, H) and forming pronounced lobe (Fig. 6 C-E); membranous part of embolus proper distally wide (Fig. 6C, F-H); distal edge of contrategulum with a single large triangular tooth (Fig. 6F, H-O); paracymbium much deeper than wide (Fig. 6B). Dorsal side of vulval plate with anterolateral corners of genital atrium bulged and elevated above level of poreplate; median hairs usually present in genital atrium (Fig. 7A, C-D, F); receptacular cluster divided into three more or less distinct subclusters (Fig. 7B, E, G)............................................................. L. endau
Distribution: All described species of this group occur in the western and southern part of peninsular Malaysia (Fig. 1, localities 1-9); an undescribed species appears to be present in the northeastern corner of the country (Fig. 1, locality 13).
description: Published as part of Peter J. Schwendinger, 2017, A revision of the trapdoor spider genus Liphistius (Mesothelae: Liphistiidae) in peninsular Malaysia; part 1, pp. 391-445 in Revue suisse de Zoologie 124 (2) on pages 393-395, DOI: 10.5281/zenodo.893555