Revision of the enigmatic Southeast Asian spider genus Savarna (Araneae, Pholcidae)
Author
Huber, Bernhard A.
Author
Petcharad, Booppa
Author
Bumrungsri, Sara
text
European Journal of Taxonomy
2015
2015-12-10
160
1
23
journal article
32669
10.5852/ejt.2015.160
65a5e6d8-d655-4949-8f4f-f5fc7930f5f4
830786
AFC4DF73-9767-4929-86F7-328ED9B65FDB
Genus
Savarna
Huber, 2005
Savarna
Huber, 2005: 76–77
.
Type
species:
S. thaleban
Huber, 2005
.
Diagnosis
Medium sized (~
2–3 mm
total body length), six-eyed spiders, with round to oval abdomen and relatively long legs (
Figs 2–13
). Distinguished from similar genera (
Spermophora
Hentz, 1841
;
Khorata
Huber, 2005
;
Aetana
Huber, 2005
) by having the long male palpal trochanter apophysis uniquely attached to the femur (
Figs 15
,
21
,
48
,
57
,
66
,
82
), and by the male cheliceral armature (laterally projecting proximal cheliceral apophyses and no further modiFcation;
Figs 16
,
45
,
55
,
63
,
83
). It furthermore differs from
Spermophora
by the absence of epigynal pockets, the absence of epiandrous spigots (
Figs 26
,
52
,
71
) and the reduction of AMS spigots to two (
Figs 24
,
53
,
61
,
70
).
Amendments to original description
Male distance PME-PME 185–255 µm. Male clypeus either with brushes of hairs (
S. kraburiensis
;
Fig. 45
), with paired processes at rim (
S. kaeo
sp. nov.
;
S. thaleban
;
S. miser
;
Figs 20
,
55
), or with median process at rim (
S. tessellata
;
Fig. 63
). Abdomen consistently with dark and white marks (the monochromous abdomen of the male
holotype
of
S. baso
– dating from 1913 – is probably an artifact). Male leg 1 ~9–10 × body length; tibia 2 either slightly longer than tibia 4 or of same length. Legs either without spines (
S. thaleban
;
S. miser
), with spines on femora 1 (
S. kraburiensis
;
S. tessellata
), or with spines on femora 1–2 and tibiae 1–3 (
S. kaeo
sp. nov.
). Male tibiae with higher than usual density of short vertical hairs. Retrolateral trichobothrium on male tibia 1 at 7–9% of tibia 1 length. Tarsus 4 with single ventral row of comb-hairs (
Figs 51
,
62
,
69
). Male gonopore without epiandrous spigots (all species examined except
S. miser
;
Figs 26
,
52
,
71
). ALS with only two spigots each (all species examined except
S. miser
;
Figs 24
,
53
,
61
,
70
).
Monophyly and relationships
Previously, the monophyly of
Savarna
was supported mainly by two unique morphological characters, the modiFcations of the male chelicerae and of the male palpal trochanter (
Huber 2005
). Preliminary analyses of molecular data of all known species (A. Valdez-Mondragón, B.A. Huber, D. Dimitrov, unpubl. data) strongly support the monophyly of
Savarna
.
The single ventral row of comb-hairs on the fourth tarsus places the genus in Pholcinae (
cf.
Huber & Fleckenstein 2008
). The morphology of the comb-hairs (‘
Belisana
-type’
sensu
Huber & Fleckenstein 2008
) suggests the genus is not part of the
Pholcus
group of genera. Preliminary analyses of molecular data strongly support this ‘basal’ position in Pholcinae. Detailed relationships with other genera among ‘basal’ Pholcinae remain obscure. The absence of epiandrous spigots is rare in Pholcinae and is otherwise known only in
Khorata
Huber, 2005
(B.A. Huber, unpubl. data on three species), in
Spermophorides
Wunderlich, 1992
(B.A. Huber, unpubl. data on one species), and in two undescribed species of unknown afFnity from Borneo (B.A. Huber, unpubl. data). Our preliminary molecular analyses do weakly support a close relationship among some of these taxa.
Natural history
Even though
Savarna
spiders also occur outside caves, all known localities are closely associated with limestone caves. Both inside and outside the caves, the spiders build domed webs close to the ground with at least one side of the web attached to the rock surface. Web diameter ranges from about
10 to 25 cm
. When disturbed, the spiders vibrate; if disturbance continues or is strong, they drop to the ground and remain motionless for a while (
cf.
Fig. 7
). Egg-sacs are covered by a sparse layer of barely visible silk and contain about 20–
30 eggs
(
cf.
Fig. 13
). For data on individual species, see descriptions below.
Composition
The genus now includes Fve species, all of which are treated below.
Distribution
Savarna
appears to be restricted to southern Thailand, mainland Malaysia, and Sumatra (
Fig. 1
; but see Addendum).
Key to species
1. Carapace without lateral marks (
Figs 12
,
75
) ……………………………………………………2
– Carapace with dark lateral marks (
Figs 2, 6
) ……………………………………………………3
2. Male clypeus with single median process (
Fig. 63
); genital bulb with two processes in opposing directions (
Fig. 65
); male palpal tibia unusually slender (
Huber 2005: Fg. 138
); epigynum posterior margin projecting medially (
Figs 32
,
72
) ……
S. tessellata
(
Simon, 1901
)
– Male clypeus with pair of rounded processes at rim (similar to
S. kaeo
sp. nov.
, cf.
Fig. 20
); bulb with single process (
Figs 79
,
81
); male palpal tibia ‘normal’, i.e., not unusually slender (
Fig. 81
); epigynum posterior margin without median projection (
Figs 34
,
84
) …
S. miser
(
Bristowe, 1952
)
3. Male genital bulb with two long processes in opposing directions (
Fig. 50
); epigynum with prominent median process (
Fig. 54
) …………
S. kraburiensis
Wongprom & Wiwatwitaya, 2015
– Male genital bulb with only one process or with much shorter processes (
Figs 14
,
22
,
60
); epigynum without median process (
Figs 28–31
) ………………………………………………4
4. Male palpal procursus strongly curved (
Huber 2005: Fg. 132
); male clypeus with very indistinct pair of lateral processes at rim (
Fig. 55
); epigynum evenly curved, without lateral posterior humps (
Figs 30–31
) ………………………………………………………
S. thaleban
Huber, 2005
– Male palpal procursus weakly curved (
Fig. 15
); male clypeus with distinct pair of lateral processes at rim provided with hair brushes (
Fig. 20
); epigynum with pair of lateral humps near posterior rim (
Figs 27–29
) …………………………………………………………
S. kaeo
sp. nov.