Galapa bella ( Gertsch & Peck, 1992 )

Huber, Bernhard A., Meng, Guanliang, García, Jimmy Cabra & Carvalho, Leonardo S., 2024, Thriving in dry conditions: on the Neotropical spider genus Galapa (Araneae: Pholcidae), Zootaxa 5419 (3), pp. 301-347 : 311-317

Galapa bella ( Gertsch & Peck, 1992)

Figs 6–11

Pholcophora bella Gertsch & Peck, 1992: 1190 , figs 32–36 (♂ ♀).

Galapa bella — Huber 2000: 101, figs 381–384, 389. Huber & Acurio 2022: 195, fig. 7. Dederichs et al. 2022: 11, fig. 12 (sperm morphology).

Diagnosis (amendments; see Huber 2000). Distinguished from mainland South and Central American congeners by much larger distal bulbal apophysis ( Fig. 7B ), by anterior rather than posterior position of large membranous element in female internal genitalia ( Fig. 11C, D ), and by body size and leg length (carapace width:>0.45; tibia 1 length:>0.60); from mainland South American congeners also by subdistal rather than distal position of retrolateral-distal process on procursus ( Fig. 7B ); from G. murphyi also by simple rather than bifid retrolateral-distal process on procursus ( Fig. 7B ).

Redescription (amendments of Huber 2000, based on specimens reported in Huber & Acurio 2022)

Male carapace width 0.47–0.53. Distance PME-PME 45 µm; diameter PME 45 µm; distance PME-ALE 15 µm; distance AME-AME 15 µm; diameter AME 30 µm. Tibia 1 in four males (including holotype): 0.66, 0.67, 0.68, 0.74; diameters of leg femora 0.10, of leg tibiae: 0.06. Clypeus not more protruding than in female, without sclerotized rim. Sternum with pair of barely visible anterior humps near coxae 1 (~5 µm high, 20 µm diameter at basis). Gonopore with four epiandrous spigots arranged in two pairs ( Fig. 6F ). ALS with one strongly widened spigot, one long pointed spigot, and five cylindrical spigots, of which one is much wider than the others ( Fig. 6C ); PMS with two conical spigots ( Fig. 6C ); PLS without spigots. Chelicerae in general very similar to congeners (cf. Huber 2000: fig. 384), with curved process proximally on fang ( Fig. 8A ); with stridulatory files consisting of ~50 ridges, distances between ridges 1.5–1.6 µm throughout, without further fine subdivision ( Fig. 8B ). Palpal femur proximally with prolateral stridulatory pick ( Fig. 8C ); femur-patella joints strongly shifted towards prolateral side; tibia oval, with two trichobothria; tibia-tarsus joints barely shifted towards retrolateral side; palpal tarsal organ strongly raised ( Fig. 9A–C ), diameter 6.7 µm, diameter of opening 1.7 µm; procursus with pointed retrolateral-distal process directed towards proximal and dorsal ( Fig. 7B ); tip of dorsal process covered by dorsal flap of genital bulb ( Fig. 7B ) but not lodged in pocket as in South American congeners; genital bulb with large distal apophysis ( Fig. 7B ), apparently without retrolateral-dorsal process and ventral processes; sperm duct opening on prolateral-ventral side directly on bulb ( Fig. 7H ). Legs with round cuticular plates ( Fig. 10A, B ; diameter 4–5 µm) and rimmed pores ( Fig. 10A–C ; outer diameter 3.4–3.7 µm, diameter of opening 0.2 µm) apparently on all leg segments. Sexually dimorphic short vertical hairs present on tibiae 1 and 2 ( Fig. 8E–H ), length ~15 µm, diameter at basis 1.2 µm. Chemoreceptive hairs similar in size (length ~13 µm, diameter at basis 1.7 µm) but with side branch ( Fig. 10F ). Retrolateral trichobothrium of tibia 1 at 60%; prolateral trichobothrium absent on tibia 1. Leg tarsal organs capsulate ( Fig. 9E, F ; diameter 3.7–4.5 µm, diameter of opening 1.0–1.4 µm). Main tarsal claws with ~10–11 tines ( Fig. 10F, G ).

Female in general similar to male but sternum without anterior humps, chelicerae without stridulatory files ( Fig. 8D ), cheliceral fangs unmodified. Tibia 1 in two females: 0.65, 0.68 ( Huber 2000). The female from Santa Cruz, near Canal de Itabaca, has longer legs (tibia 1: 0.78) and a CO1 distance to specimens from 1 km SW of Garrapatero beach of 8.8–9.0%. It may in fact represent a different species. Spinnerets as in male ( Fig. 6B, D ). Epigynum ( Figs 6E , 11A, B ) with simple semicircular anterior plate, weakly protruding, posteriorly not indented medially; posterior plate short and simple, without median division. Internal genitalia ( Fig. 11C, D ) very simple, apparently without pore plates; membranous bilobed structure with short median process, covered by anterior epigynal plate (not by posterior epigynal plate as in South American congeners).

Distribution. Known from several localities on Santa Cruz Island, Galápagos. The single female reported from Santa Cruz, Islote Venecia (~ 0.5178°S, 90.4760°W), by Gertsch & Peck (1992), may also represent this species rather than G. baerti . The species has been claimed to be present on Genovesa and Pinta Islands ( Baert et al. 2008; Baert 2013, 2014) but without specimen and collection data, so these records are here considered dubious.

Natural history. At the type locality (Charles Darwin Research Station), the species seems to have been replaced by the introduced Modisimus culicinus (Simon, 1893) ( Huber & Acurio 2022) . The specimens newly collected in 2019 (listed in Huber & Acurio 2022) were found in very dry and exposed habitats near the sea, under rocks and small stones and pebbles ( Fig. 5A, B ). At both localities (near Garrapatero beach and near Canal de Itabaca), the spiders occupied the drier upper layer of stones, while Anopsicus banksi (Gertsch, 1939) was found in the deeper, slightly more humid layers. The spiders ran very quickly when disturbed.

Figures

FIG. 6. Galapa bella (Gertsch & Peck, 1992) from Santa Cruz, SW of Garrapatero beach. A. Female prosoma, dorsal-frontal view. B. Female ALS. C. Male ALS and PMS. D. Female ALS. E. Epigynum, ventral view. F. Male gonopore and epiandrous spigots. Abbreviations: aep, anterior (main) epigynal plate; ALS, anterior lateral spinneret; pep, posterior epigynal plate; PMS, posterior median spinneret. Scale bars: 100 µm (A, E), 10 µm (B–D, F).

FIG. 7. Galapa bella (Gertsch & Peck, 1992), male from Santa Cruz, SW of Garrapatero beach. A–D. Left palp, retrolateral to dorsal views. E–G. Right palp, prolateral to dorsal views. H. Genital bulb, prolateral-ventral view, showing position of sperm duct opening. Abbreviations: b, genital bulb; dp, dorsal process of procursus; da, distal apophysis of genital bulb; f, femur; pr, procursus; rp, retrolateral-distal process of procursus; sd, sperm duct opening. Scale bars: 100 µm.

FIG. 8. Galapa bella (Gertsch & Peck, 1992) from Santa Cruz, SW of Garrapatero beach. A. Right male cheliceral fang, frontal view; arrow points at proximal process on fang. B. Stridulatory file on left male chelicera. C. Stridulatory pick on male palpal femur. D. Right female chelicera, showing absence of stidulatory file. E, F. Left male tibia 1, prolateral views. G. Right male tibia 1, retrolateral view. H. Single ‘short vertical hair’ and base of regular mechanoreceptor on left male tibia 2. Scale bars: 10 µm (A–C, F, G), 20 µm (D), 100 µm (E), 2 µm (H).

FIG. 9. Galapa bella (Gertsch & Peck, 1992) from Santa Cruz, SW of Garrapatero beach. A. Right male palpal tarsus, dorsal view, showing position of tarsal organ (arrow). B, C. Male palpal tarsal organ. D–F. Tarsal organs on female tarsus 2, male tarsus 4, and male tarsus 1. Scale bars: 10 µm (A, B), 2 µm (C–F).

FIG. 10. Galapa bella (Gertsch & Peck, 1992) from Santa Cruz, SW of Garrapatero beach. A, B. Rimmed pores and cuticular plates on male tibia 4 and on female tibia 2. C. Rimmed pore on male metatarsus 2. D. Base of trichobothrium on left male metatarsus 1. E. Right male metatarsus-tarsus joint, retrolateral-dorsal view. F, G. Tips of right male tarsi 3 and 4, retrolateral views (arrows: putative chemoreceptors). Scale bars: 2 µm (A, B), 1 µm (C), 10 µm (D–G).

FIG. 11. Galapa bella (Gertsch & Peck, 1992) females from Santa Cruz, SW of Garrapatero beach; ZFMK Gal55. A, B. Abdomens, ventral views. C, D. Cleared internal genitalia, dorsal views. Scale bars: 0.2 mm.

FIG. 5. Typical habitats of Galapa spp. A–B. Galápagos, Santa Cruz, near Garrapatero beach and near Canal de Itabaca (G. bella). C. Colombia, Magdalena, near Santa Marta (G. gabito). D. Colombia, La Guajira, near Papayal (G. spiniphila). E–F. Costa Rica, Guanacaste, NW of Cañas and S of La Cruz (G. murphyi). Photos BAH.