Pholcus halabala

Berhard A. Huber, Booppa Petchard, Charles Leh Moi Ung, Joseph K. H. Koh & Amir R. M. Ghazali, 2016, The Southeast Asian Pholcus halabala species group (Araneae, Pholcidae): new data from field observations and ultrastructure, European Journal of Taxonomy 190, pp. 1-55 : 3-7

Pholcus halabala species group

Diagnosis

The core group of six species (see below) includes medium-sized, long-legged spiders (body length ~3–4, male leg 1 length ~30–40); distinguished from other species groups in Pholcus by the combination of the following characters: elongate abdomen pointed dorso-posteriorly, with distinctive dorsal pattern of black and whitish or yellowish marks in life specimens ( Figs 1–16 ; similar only in Ph. sudhami Huber, 2011 , cf. Figs 54–56 ); eight eyes; male ocular area with conspicuous modified hairs (setae), which may appear as stiff bristles or stout curved spines, or both ( Figs 19, 23 , 43 ); male chelicerae with proximal and distal apophyses, distal apophyses with two cone-shaped teeth (modified hairs) each ( Fig. 28 ); male bulb with uncus and appendix; procursus with distinctive dorsal flap ( Fig. 35 ; absent in Ph. erawan Huber, 2011 ); epigynum weakly sclerotized, with ‘knob’.

Description – amendments

The original description of the core group ( Huber 2011) is still largely valid. The following can be added: male eye triads on low humps ( Figs 18, 20 , 43 ; i.e., not on short stalks as seen in Ph. krabi group) and only slightly wider apart than female eye triads (1.2–1.5 ×); dorsal elongation of male palpal tarsus usually short and conical (asterisk in Fig. 30 ), long in Ph. erawan Huber, 2011 (fig. 1467 in Huber 2011); procursus usually with dorsal flap, absent in Ph. erawan ; tibia 1 in males ~6–9, in females ~6–8; male gonopore with four epiandrous spigots ( Figs 26 , 44 ; confirmed in Ph. halabala and Ph. erawan ); ALS with eight spigots each (one widened, one pointed, and six smaller cylindrically shaped spigots of varying sizes, Figs 25 , 45 ; confirmed in Ph. halabala and Ph. erawan ); web consists mostly of flat round platform closely attached to underside of leaf; web sometimes with large numbers of small silk tufts ( Figs 4 , 16 ; confirmed for Ph. halabala , Ph. erawan and Ph. sepaku ); female holds egg-sac under body rather than in front of it ( Figs 3, 5–6 , 16 ; confirmed for Ph. halabala , Ph. erawan and Ph. sepaku ).

Composition

The 13 species assigned to this group are here divided into two operational sub-groups: a core-group of six species for which the evidence for monophyly is considered to be strong ( Ph. erawan Huber, 2011 ; Ph. halabala Huber, 2011 ; Ph. lintang Huber , sp. nov.; Ph. sabah Huber, 2011 ; Ph. sepaku Huber, 2011 ; Ph. ubin sp. nov.); and a sub-group of seven species whose assignment is tentative [ Ph. elongatus (Yin & Wang, 1981) ; Ph. exceptus Tong & Li, 2009 ; Ph. khaolek Huber , sp. nov.; Ph. kuhapimuk Huber , sp. nov.; Ph. pakse Huber, 2011 ; Ph. pyu Huber, 2011 ; Ph. sudhami Huber, 2011 ].

The composition of the group changes as follows: to the original core group consisting of three species ( Ph. halabala ; Ph. sabah ; Ph. sepaku ) we add two newly described species ( Ph. ubin Huber , sp. nov.; Ph. lintang sp. nov.) as well as Ph. erawan . The latter species was originally part of another problematic species group ( Pholcus quinquenotatus group; Huber 2011: 290). It lacks the distinctive dorsal flap on the procursus that is present in the other five species of the core group, and the hairs in the male ocular area are not particularly strong, but it is moved into the core group because (1) it builds the same distinctive web closely attached to the leaf surface as the five other species; (2) webs are provided with facultative silk tufts like in Ph. halabala and Ph. sepaku (otherwise only known in the African genus Smeringopus Simon, 1890 ; Huber 2012); (3) females carry the egg-sac under the body like Ph. halabala and Ph. sepaku , which is unique among Pholcidae ; (4) life specimens have an almost identical distinctive pattern of large whitish to yellowish and black spots on the abdomen, and on the carapace a pair of V-marks; and (5) the procursus is provided with a distinctive retrolateral distal pocket also present in Ph. halabala ( Figs 21–22 , 41 ). Preliminary molecular data (A. Valdez-Mondragón, B.A.

Huber & D. Dimitrov unpublished data), including all species of the core group except Ph. sepaku (i.e., also Ph. erawan ), strongly support the monophyly of this group. The RMNH has three further species of the core group from Sabah ( Fig. 17 ), but the specimens are poorly preserved and for this reason not formally described here.

In addition to this core group, we include in the Ph. halabala group two further species that were previously part of the Pholcus quinquenotatus group ( Ph. sudhami Huber, 2011 ; Ph. pakse Huber, 2011 ) as well as two newly described species ( Ph. kuhapimuk sp. nov.; Ph. khaolek sp. nov.).Again, preliminary molecular data (A. Valdez-Mondragón, B.A. Huber & D. Dimitrov unpublished data) strongly support a close relationship of these four species with the core group, and at least Ph. sudhami and Ph. pakse share some morphological similarities with the core group (carapace and abdomen pattern, male eye triads on low humps, large AME, male cheliceral apophyses with modified hairs), but no putative morphological synapomorphy is known that would support this close relationship. The microhabitat of these four species differs from the core group (rocks and tree roots rather than foliage); egg-sacs are carried in front of the body as in typical pholcids; webs were never seen to be provided with silk tufts. In addition, males of Ph. sudhami and Ph. pakse lack stronger hairs in the ocular area, and both species lack the bulbal appendix.

Three species originally assigned to the halabala group are kept in the group simply for the lack of a better solution: Ph. pyu Huber, 2011 ; Ph. elongatus (Yin & Wang, 1981) ; and Ph. exceptus Tong & Li, 2009 . Data on natural history and ultrastructure are not available for any of them, nor is any of them included in our preliminary molecular analysis (A. Valdez-Mondragón, B.A. Huber & D. Dimitrov unpublished data). We speculate that Ph. pyu may in fact belong to this group, but the other two species are quite certainly misplaced. Pholcus elongatus lacks AME; males in this species have short eye stalks and pointed cheliceral apophyses without modified hairs; females have a long epigynal scape. We speculate that the closest relatives of Ph. elongatus are the Taiwanese species Ph. pingtung Huber & Dimitrov, 2014 and Ph. chengpoi Huber & Dimitrov, 2014 (six eyes; similar cheliceral apophyses; scape directed toward anterior). Pholcus exceptus is a mysterious species with entirely reduced distal cheliceral apophyses.

Finally, five species originally included in the Pholcus halabala group are transferred to new species groups (see below): Ph. andulau Huber, 2011 ; Ph. chiangdao Huber, 2011 ; Ph. khene Huber, 2011 ; Ph. kinabalu Huber, 2011 ; and Ph. satun Huber, 2011 .

Natural history

All six species of the core group were observed in the field. At most localities, abundances seemed very low. Surprisingly, several species were partly or exclusively found in degraded forests. All specimens seen during the day were tightly pressed against the undersides of mostly large leaves. Webs consisted mainly of round platforms with a diameter of about 10 cm; most of the platform was closely attached to the leaf surface. Small silk tufts ( Figs 4 , 16 ) were observed in some webs of three species ( Ph. halabala ; Ph. erawan ; Ph. sepaku ), but may occur in other species as well (very few specimens seen in other species). The same applies to the peculiar position in which egg-sacs are held by females: in Ph. halabala , Ph. erawan and Ph. sepaku (and possibly in close relatives), the egg-sac is carried under the prosoma rather than in front of it ( Figs 3, 5–6 , 16 ). For further details, see individual species descriptions below.

Three of the four species assigned tentatively to the halabala group based on preliminary molecular data were observed in the field ( Ph. kuhapimuk sp. nov.; Ph. khaolek sp. nov.; and Ph. sudhami ), and these were mostly found on rocks at cave entrances, with the body flat on the rock surface. Only Ph. sudhami at Erawan was mostly found on exposed tree roots at the riverside. Webs were either barely visible (a few threads close to the rock surface) or consisted of very delicate small domed sheets attached to the rock ( Ph. khaolek sp. nov.). Silk tufts were not seen in any of these webs. Egg-sacs were carried in front of the body as in typical pholcids ( Fig. 51 ).

Distribution

The Ph. halabala group is restricted to Southeast Asia, from Myanmar and southern China to Sumatra and Borneo ( Figs 17 , 57 ).

Figures

Fig. 17. Known distribution of the core group of the Pholcus halabala species group.

Fig. 57. Known distributions of species tentatively assigned to the Pholcus halabala species group.

Figs 1 – 8. Live specimens, Pholcus halabala Huber, 2011 (1 – 6) and Ph. ubin Huber, sp. nov. (7 – 8). 1. ♂ from MacRitchie, Singapore. 2. ♂ from Gunung Jerai, Malaysia. 3. ♀ with egg-sac from Gunung Liang, Malaysia. 4. Juvenile in web with silk tufts, Upper Selatar, Singapore. 5. ♀ with egg-sac from Hala Bala, Thailand. 6. ♀ with egg-sac from Ulu Dong, Malaysia. 7 – 8. ♂ and ♀ from Pulau Ubin, Singapore.

Figs 9 – 16. Live specimens, Pholcus sabah Huber, 2011 (9 – 10), Ph. lintang Huber, sp. nov. (11 – 12) and Ph. erawan Huber, 2011 (13 – 16). 9. ♂ from Poring, Sabah. 10. ♂ from Sepilok, Sabah. 11 – 12. ♂ and ♀ from Bako, Sarawak. 13. ♂ from Khao Nan, Thailand. 14. Male from Erawan, Thailand. 15 – 16. ♂ and ♀ with egg-sac from Gunung Jerai, Malaysia.

Figs 49 – 56. Live specimens, Pholcus kuhapimuk Huber, sp. nov. (49 – 51), Ph. khaolek Huber, sp. nov. (52 – 53), and Ph. sudhami Huber, 2011 (54 – 56). 49 – 51. ♂, penultimate instar ♂, and ♀ with egg-sac from Wat Kuhapimuk, Thailand. 52 – 53. ♀ with spiderlings and ♂ from Khao Lek, Thailand. 54 – 55. ♂ from Tham Phraya Nakhon, Thailand. 56. ♂ from Erawan, Thailand.

Figs 18 – 28. Pholcus halabala Huber, 2011, ZFMK Ar 15008. 18. Male ocular area, frontal view. 19. Modified hairs on male ocular area, dorsal view. 20. Male prosoma, frontal view. 21 – 22. Right procursus (and trochanter apophysis), retrolateral and retrolatero-distal views (arrows point at distal pocket). 23. Modified hairs on male ocular area. 24. Left bulbal processes, prolateral (slightly ventral) view. 25. Male ALS. 26. Male gonopore. 27. Comb-hairs on male tarsus 4. 28. Male distal cheliceral apophysis. Abbreviations: a = appendix; AME = anterior median eyes; e = embolus; p = procursus; tr = trochanter; u = uncus. Scale lines: 10 µm (25, 27); 20 µm (28); 30 µm (23); 40 µm (26); 80 µm (24); 100 µm (19, 21 – 22); 200 µm (18); 300 µm (20).

Figs 39 – 48. Pholcus erawan Huber, 2011, ZFMK Ar 15016 – 17. 39. Male distal cheliceral apophysis (arrows point at modified hairs). 40. Left procursus, prolateral view. 41. Right procursus, retrolatero-dorsal view (arrow points at distal pocket). 42. Left bulbal processes, distal view. 43. Male ocular area, frontal view. 44. Male gonopore. 45. Female ALS. 46. Comb-hairs on male tarsus 4. 47. Female prosoma, frontal view. 48. Epigynum, ventral view. Abbreviations: a = appendix; e = embolus; u = uncus. Scale lines: 10 µm (39); 20 µm (45 – 46); 40 µm (44); 60 µm (42); 80 µm (40); 100 µm (41, 48); 200 µm (43, 47).

Figs 34 – 38. Pholcus lintang Huber, sp. nov., ZFMK Ar 15015. 34 – 35. Left male palp, prolateral and retrolateral views. 36. Male chelicerae, frontal view. 37 – 38. Cleared female genitalia, ventral and dorsal views. Abbreviations: a = appendix; b = genital bulb; e = embolus; p = procursus; u = uncus. Scale lines: 0.3 mm (36 – 38); 0.5 mm (34 – 35).

Figs 29 – 33. Pholcus ubin Huber, sp. nov., ZFMK Ar 15011. 29 – 30. Left male palp, prolateral and retrolateral views (arrow points at distinctive dorsal process; asterisk marks dorsal elongation of male palpal tarsus). 31. Male chelicerae, frontal view. 32 – 33. Cleared female genitalia, ventral and dorsal views. Abbreviations: a = appendix; b = genital bulb; e = embolus; p = procursus; u = uncus. Scale lines: 0.3 mm (31); 0.5 mm (29 – 30, 32 – 33).