Otacilia tham Jäger 2022

Figs 1–6, 8–14, 18

Otacilia tham Jäger 2022: 148, figs 1–9, 25–26

(Description of female; holotype female from LAOS: Vientiane Province: Vang Vieng, N of Ban Phoxay, Tham Loup, 19°2’18.7”N, 102°25’22.43”E, 290 m, dark part of the cave, 100–200 m from cave entrance (Fig. 27), P. Jäger & S. Packheiser leg. 23.07.2018, SMF; 1 female paratype with same data as for holotype except for: P. Jäger leg. 9.10.2022, SMF; 3 female paratypes with same data as for holotype except for: P. Jäger leg. 10.10.2022, SMF [1 female], NSMT [2 females]; 2 females with same data as for holotype except for: P. Jäger leg. 14.10.2022, SMF; all examined).

Additional material examined. 1 male, 1 female, LAOS: Vientiane Province: north of Vang Vieng, Ban Nadao, Tham Loup, 19°2’17.75”N, 102°25’25.28”E, 269 m, dark part of the cave, first 65 m of main dark (left) chamber (see green dotted line in Fig. 14), ca. 120 square metres searched, P. Jäger leg. 6.12.2023 (SMF). 1 female, 2 juveniles with same data as for previous specimen except for: 4.12.2023 (SMF).

Diagnosis. Males of O. tham are unique among those of all congeners in having only non-functional (i.e. unpigmented) remnants of the ALE and PLE (Fig. 11). The palp (Figs 1–6, 8–9) is very similar to that of O. saszykaska in having a hook-like DTA, a stiletto-shaped RTA and the embolus mostly covered by the conductor in ventral view, but can be distinguished by: 1. DTA prolaterally with small bulge in dorsal view, 2. Tegulum much wider than cymbium especially in proximal half, 3. Spermophor with right-angled bend shortly before entering embolus, 4. Conductor and tegular apophysis separated by narrow gap (DTA with large and right-angled bulge, tegulum barely wider than cymbium, spermophor with obtuse-angled bend, conductor covering large parts of tegular apophysis in O. saszykaska; see Jäger 2022: figs 11–13). For the female, see Jäger (2022).

Description. Male. PL 1.06, PW 0.85, AW 0.45 OL 1.13, OW 0.77. Eye diameters (Fig. 11) ALE 0.04, PLE 0.02; interdistances ALE–PLE 0.025, PLE–PLE 0.13, clypeus height at ALE 0.05. Palp and leg measurements: palp 1.61 (0.47, 0.24, 0.29, -, 0.61), I 5.86 (1.49, 0.47, 1.70, 1.39, 0.81), II 5.05 (1.30, 0.43, 1.36, 1.11, 0.85), III 4.69 (1.24, 0.41, 1.15, 1.20, 0.89), IV 6.70 (1.77, 0.45, 1.61, 1.75, 1.12); leg formula: 4123. Spination of palp and legs: palpal femur 010, patella 110, tibia 110; femora I 500, II 300, III–IV 000; tibiae I 000 15, II 000 14, III–IV 0000; metatarsi I–II 0008, III–IV 0000. Chelicerae with 2 promarginal, 3 retromarginal teeth, the latter increasing in size proximally, 2 strong spines frontally, and 1 long and 5–6 short escort setae. Metatarsus III with strong, IV with weaker distal field of setae ventrally.

Palp as in diagnosis (Figs 1–6, 8–9). Femur with distinct hump in lateral view, with small prolateral bulge and longer retrolateral ridge with shallow cavity (best seen in ventral view). RTA narrowly triangular in retrolateral view, not reaching tegular margin, DTA with broad base and apical prolaterad hook (best seen in dorsal view). Tegulum pear-shaped, extending proximally almost up to tibial distal margin. Conductor bluntly pointed in ventral view. Tegular apophysis elongated triangular, distad. Embolus short, filiform and curved, hidden behind conductor in ventral view. Spermophor mainly visible as broad “U”, before narrowing and entering embolus.

Colouration (Figs 10–11). Pale yellowish brown without pattern. Fovea and striae faintly marked. Opisthosoma dorsally slightly greyish. Live spiders with shiny appearance (Fig. 12).

Female. See Jäger (2022).

Variation. Females (n = 2): PL 1.07–1.14, OL 1.15–1.61. Spination: tibiae I 000 15–18, II 000 14–16; metatarsi II 0008(7). Juveniles (n = 2): PL 0.82, Spination: femora I 500, II 300; tibiae I 000 14, II 000 13; metatarsi I 0008, II 0007. PL 0.61 (Fig. 18), Spination: femora I 300, II 100; tibiae I 0008, II 0008; metatarsi I 0008, II 0007.

Distribution. Known only from the type locality, Tham Loup, Vientiane Province, Laos (Figs 13–14).

Natural history. In addition to the description in Jäger (2022), spiders were found in another large (right) chamber, thus occupying almost all sites in the aphotic zone (Fig. 14), similar to individuals of Sinopoda caeca Grall & Jäger 2020 (Araneae: Sparassidae). Spots with litter and potential prey such as Diptera or Collembola (Figs 19–20) were more densely occupied. This was also true for two sites where litter (twigs, leaves) were deliberately left in the cave during a visit in 2022. These were found in 2023 to have the same increased abundance of animals as the other sites with organic material. Apparently, all the organic material was introduced by humans, as the cave is a fossil cave with no (major?) connection to the neighbouring Tam Hoi or other caves (Diraison 2005: 99) where organic material could be swept in during the rainy season.

The behaviour of Otacilia tham spiders (females and juveniles observed) was similar to that of S. caeca: when disturbed (breath blown in their direction), the spiders briefly sprinted, also similar to Oonopidae. After the sprint, they stopped and after a short time they went into a resting position with the legs oriented in their characteristic position and the body lowered close to the ground. Most of the time, they sat still.

In addition to the faunistic report in Jäger (2022), the following animals were recorded from Tham Loup: one species each of: Trombidiidae Leach 1815 (Acari; Fig. 16), Eutrichodesmus Silvestri 1910 (Diplopoda; Fig. 21), Trichopeltis Pocock 1894 (Diplopoda; Fig. 22), Entomobryidae Schäffer 1896 (Collembola; Fig. 20), Schizomida (Fig. 17), Phlebotominae Rondani, 1840 (Diptera: Psychodidae Newman, 1834; Fig. 19) and Isopoda (Fig. 23). An almost unpigmented individual of Dermaptera, several larvae of Diptera in a pool at the very west end of the cave, and three individuals of Reduviidae Latreille 1807 were also observed. An immature female of S. caeca (Fig. 15) was observed when feeding on a juvenile cave cricket (Raphidophoridae Walker 1869); live specimens of the latter family were observed at various stages throughout the cave. Heteropoda aemulans Bayer & Jäger 2009 (Araneae: Sparassidae) was recorded from the entrance hall and darker areas, as well as an unidentified species of the genus Zoica Simon 1898 (Lycosidae Sundevall 1833) and the family Pholcidae C.L. Koch 1850. A species of an unidentified Pompilidae Latreille 1804 (“ Pepsis ”, spider hawk wasp) was recorded flying in the cave a few times, once with paralysed prey (Heteropoda sp.), which was dragged close to the ground into crevices formed by a stalagmite.