Pholcus tambunan

Bernard A. Huber, Joseph K. H. Koh, Amir-Ridhwan M. Ghazali, Kamil A. Braima, Olga M. Nuñeza, Charles Leh Moi Ung & Booppa Petcharad, 2016, New leaf- and litter-dwelling species of the genus Pholcus from Southeast Asia (Araneae, Pholcidae), European Journal of Taxonomy 200, pp. 1-45 : 25

Pholcus tambunan species group

Diagnosis

The two species included in this group are medium-sized, long-legged spiders (body length ~4, male leg 1 length: ~35–40), distinguished from other species groups in Pholcus by combination of the following characters: elongate abdomen angular dorso-posteriorly ( Figs 94, 98 ); six eyes; male chelicerae with distinctive distal apophyses (flat sclerites without modified hairs; Figs 103 , 108 , 120 ); most palpal structures unusually long (in particular genital bulb; Figs 101 , 121 ); male bulb without uncus; epigynum weakly sclerotized, scape directed towards anterior with terminal ‘knob’ ( Figs 104 , 123 ); female internal genitalia with pair of highly distinctive three-layered telescopic tubes ( Figs 105 , 124 ).

Description

See individual descriptions of the two very similar species below.

Composition

Only the two species described below.

Natural history

Both species were found on the undersides of live leaves where they built very fine webs tightly attached to the leaf surface. Both species were frequently seen to share their webs with cecidomyiid flies. For further information, see descriptions below.

Distribution

The P. tambunan group is restricted to northern Borneo ( Fig. 1 ).

Figures

Fig. 1. Known distributions of the Pholcus ethagala group (Malay Peninsula and Sumatra; Sri Lankan species not shown), of the P. tambunan group (Borneo) and of the P. domingo group (Philippines).

Figs 93 – 100. Live specimens. 93 – 96. Pholcus tambunan Huber sp. nov., Crocker Range, ♂, penultimate ♂, and ♀ with egg-sac. 97 – 100. P. bario Huber sp. nov., Bario, ♂ and ♀ with egg-sac.

Figs 101 – 105. Pholcus tambunan Huber sp. nov. (ZFMK, Ar 15711 – 12). 101 – 102. Left male palp, prolateral and retrolateral views. 103. Male chelicerae, frontal view. 104 – 105. Cleared female genitalia, ventral and dorsal views. Scale bars: 101 – 102, 104 – 105 = 0.5 mm; 103 = 0.3 mm.

Figs 106 – 113. Pholcus tambunan Huber sp. nov., SEM micrographs (ZFMK, Ar 15711, 15715). 106 – 107. Male and female prosomata, frontal views. 108. Right male cheliceral apophysis. 109. Right procursus, retrolateral view. 110. Left procursus, prolateral view. 111. Proximal parts of left appendix and embolus. 112. Male ocular area, dorsal view. 113. Comb-hairs on male tarsus 4. Scale bars: 106 – 107, 112 = 200 µm; 108 = 20 µm; 109 – 111 = 100 µm; 113 = 10 µm.

Figs 120 – 124. Pholcus bario Huber sp. nov. (ZFMK, Ar 15717 – 18). 120. Male prosoma, frontal view. 121 – 122. Left male palp, prolateral and retrolateral views; arrow points at prolateral finger-shaped process of procursus. 123 – 124. Cleared female genitalia, ventral and dorsal views. Scale bars: 120, 123 – 124 = 0.3 mm; 121 – 122 = 0.5 mm.