Galapa Huber, 2000

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 : 307-311

Genus Galapa Huber, 2000

Galapa Huber, 2000: 100 . Type species by original designation: Pholcophora baerti Gertsch & Peck, 1992 .

Galapa — Huber & Villarreal 2020: 58 .

Diagnosis. Tiny (body length ~1.0– 1.5 mm), short-legged, eight-eyed pholcids with globular abdomen ( Fig. 2 ). Males are easily distinguished from all other known Ninetinae by modified cheliceral fangs and by absence of frontal modifications on base segment of chelicera ( Figs 3 , 8A , 13C ). Similar chelicerae occur only in the distantly related Modisiminae genus Chibchea Huber. Further distinguished by dorsal process on procursus ( Figs 7B , 14B , 21B ; similar only in the southern South American genus Guaranita Huber ), and by retrolateral distal process on procursus ( Figs 7B , 14B , 21B ). Females are externally very similar to other small New World Ninetinae such as Guaranita , Tolteca Huber , and Kambiwa Huber (in terms of body size, body shape, coloration, leg length, and simple epigynal plate); distinguished from these by internal genitalia: large membranous structure ( Figs 11D , 16F , 24G ) rather than pair of receptacles ( Tolteca ) or median receptacle ( Guaranita , Kambiwa ).

Description (amendments; see Huber 2000).

Male

MEASUREMENTS.Total body length~1.0–1.5.Male carapace width0.38–0.60.Distance PME-PME35–45µm; diameter PME30–45 µm;distance PME-ALE 15µm;distanceAME-AME 10–15 µm;diameterAME 15–30µm.Tibia 1 length 0.41–0.74.Tibia 1 L/d:9–10.Leg formula 4123. Diameters of leg femora 0.075–0.10, of leg tibiae:0.05–0.06.

COLOUR (in ethanol). Prosoma and legs pale ochre-yellow, carapace without pattern, legs without darker rings; abdomen ochre-grey, monochromous or with indistinct internal marks.

BODY. Ocular area not raised. Carapace without thoracic groove ( Figs 6A , 20A , 27A ). Clypeus either not more protruding than in females (Galapagos species) or slightly more protruding than in females and with sclerotized rim (mainland species), in G. murphyi also with cluster of sexually dimorphic hairs ( Fig. 27C ). Sternum slightly wider than long, with pair of indistinct anterior humps near coxae 1 ( Fig. 13D ; ~5–20 µm high, 20 µm diameter at basis). Abdomen globular. Gonopore either with four epiandrous spigots arranged in two pairs ( G. baerti , G. bella , G. gabito ; Figs 6F , 13E ; see also Huber 2000: fig. 127) or without epiandrous spigots ( G. spiniphila , G. murphyi ; Figs 20E , 28E, F ). ALS with one strongly widened spigot, one long pointed spigot, and five cylindrical spigots, of which one is much wider than the others ( Figs 6C , 22A, B , 28A ); PMS with two conical spigots ( Figs 6C , 22A , 28A ); PLS without spigots.

CHELICERAE. Chelicerae main segment unmodified ( Fig. 3 ); with stridulatory files consisting of ~30–50 ridges, distances between ridges either constant throughout (1.5–1.6 µm) or wider proximally (2.0 µm) than distally (1.1 µm), either with or without further fine subdivision ( Figs 8B , 13A , 20C , 27F ). Fang with curved proximal process ( Figs 8A , 13C , 27E ).

PALPS. Palpal coxa unmodified. Trochanter without process or with very short ventral protrusion. Femur proximally with prolateral stridulatory pick (modified hair; Figs 8C , 20D ), distally slightly widened but without modification. Femur-patella joints variably shifted towards prolateral side. Tibia oval, with two trichobothria. Tibia-tarsus joints slightly shifted towards retrolateral side. Palpal tarsal organ weakly to strongly raised ( Figs 9A–C , 14E , 23D , 29E ; see also Huber 2000: fig. 77), diameter 4.1–6.7 µm, diameter of opening 1.0–1.7 µm. Procursus retrolateral distal process simple ( Figs 7B , 14B , 21B ) or bifid ( Fig. 25B , 29C ); dorsal process curved towards prolateral; tip of dorsal process covered by large flap of genital bulb or lodged in pocket of genital bulb ( Figs 7B , 14B , 21B ). Genital bulb with distal apophysis ( Figs 7B , 17B, C , 25B, C ), in G. spiniphila also with retrolateral-dorsal process and pair of ventral processes ( Figs 17 , 21C, D ); in G. gabito and G. murphyi with small prolateral distal apophysis (arrows in Figs 12B , 25A ; 29D ); sperm duct opening on prolateral-ventral side directly on bulb ( Figs 7H , 21D , 29D ).

LEGS. Without spines and curved hairs. Without slender metatarsal hairs (as described in Huber et al. 2023c). Sexually dimorphic short vertical hairs present on tibiae 1 and 2 ( Figs 8E–H , 15A, B , 23A, B , 30A ), barely visible in dissecting microscope, length ~15–17 µm, diameter at basis 1.0–1.2 µm. Chemoreceptive hairs similar in size (length ~10–14 µm, diameter at basis 1.3–1.7 µm) but with side branch ( Fig. 30B, C ) and mostly near leg tips. Retrolateral trichobothrium of tibia 1 at 52–66%. Prolateral trichobothrium absent on tibia 1. Base of trichobothria either evenly rounded ( Fig. 10D ) or with proximal ridge ( Figs 15C , 30D, E ). Legs with round cuticular plates ( Figs 10A, B , 15D , 23F , 30E , 31F ; diameter 4–7 µm) and rimmed pores ( Figs 10A–C , 15E , 23G , 31F ; outer diameter 3.0–3.7 µm, diameter of opening 0.2–0.4 µm) apparently on all leg segments. Tarsus 1 with five pseudosegments, fairly distinct. Leg tarsal organs capsulate ( Figs 9D–F , 31A–E ; diameter 2.0–4.5 µm, diameter of opening 0.7–1.4 µm). Main tarsal claws with ~9–11 tines ( Figs 10F , 22F , 30F ). Claws of tarsus 4 different from others (tines more directed towards distal; Fig. 10G ).

Female

In general, similar to males but sternum without pair of anterior humps, chelicerae without stridulatory files ( Figs 8D , 13B , 27G ), cheliceral fangs unmodified, clypeus never strongly protruding ( Fig. 27D ) and without sclerotized rim, and palpal tarsal organ less strongly raised ( Figs 14F , 29F ; see also fig. 76 in Huber 2000) and slightly smaller (diameter 4.0–4.3 µm, diameter of opening 1.0–1.2 µm). Legs slightly shorter than in males (male / female tibia 1 length: ~1.0–1.2); tibia 1 length 0.37 – 0.74. Spinnerets as in male ( Figs 6B , 13F , 22C, D , 28C ). Epigynum with simple semicircular anterior plate, weakly protruding, posteriorly straight or indented medially ( Figs 6E , 20F , 28D ); posterior plate short and simple, with or without indistinct median division. Internal genitalia ( Figs 11 , 16 , 24 , 32 ) very simple, apparently without pore plates; with large membranous structure (with or without median membranous process), either directed towards posterior and covered by posterior epigynal plate or directed towards anterior and covered by anterior epigynal plate.

Relationships. Molecular (UCE) data (G. Meng, L. Podsiadlowski, B.A. Huber, unpubl. data) suggest that the closest known relative of Galapa is an undescribed species from Brazil, Piauí, Parque Nacional da Serra da Capivara. That species is known from a single male specimen that does not share any of the diagnostic genital characters of Galapa listed above. Together, these two clades are sister to Kambiwa + Pemona , two further South American genera. All of these together are sister of the southern South American genus Guaranita . Thus, Galapa is deeply nested within South American Ninetinae .

Even though a NJ tree ( Fig. 1 ) is not supposed to reliably reflect phylogeny, it shows two splits worth mentioning. First, within Galapa , G. bella (Galapagos) is sister to the mainland species. Several morphological characters support this split: (1) Mainland species share a proximal ridge on the basis of the leg trichobothria; in G. bella , these bases are round, which is likely the plesiomorphic condition; (2) in mainland species, the male palpal tarsal organ has moved to the procursus, while in G. bella it has the plesiomorphic position on the tarsus; (3) in mainland species, the female internal genitalia are directed towards posterior, while in G. bella they are directed towards anterior, which is probably the plesiomorphic condition; (4) finally, body size and leg length are smaller in mainland species than in species from Galapagos (carapace width: ~0.4 vs. ~0.5; tibia 1 length:>0.60 versus <0.55); the plesiomorphic condition is unknown.

Second, the Central American (Costa Rican) G. murphyi is nested within a group of mainland South American species. This position is supported by the loss of epiandrous spigots in G. murphyi and G. spiniphila , while G. bella and G. gabito share the plesiomorphic presence of four epiandrous spigots.

Distribution. The genus is known from Galápagos, northern Colombia, northeastern Venezuela, and Costa Rica ( Fig. 4 ). The distribution map of these tiny and poorly collected spiders suggests a wide range, but the ecological conditions (semi-arid, exposed habitats; see below) are not common in this region, so the suitable habitats may actually be quite limited. This is supported by our biogeographic analysis (see below).

Natural history. Representatives of the genus Galapa appear restricted to semi-arid and sun-exposed habitats where they occupy the leaf litter, spaces under stones, and dead cacti and dry branches lying on the ground and hollowed by termites ( Fig. 5 ). We never found them in neighboring, more forested, shaded, and humid sites. When disturbed, they ran rapidly. In glass vials, both males and females built small webs on which they were seen resting a few hours after being captured ( Fig. 2D ). Egg-sacs are flat (a single layer of eggs) and contain up to six eggs that are wrapped by a few barely visible silk lines; egg diameters range from 0.38 to 0.43 mm. For further information, see individual natural history sections below.

Composition. The genus now includes six nominal species: three on the Galápagos, one in Costa Rica (with a dubious record in Colombia), and two in northern South America.

Figures

FIG. 2. Galapa Huber, 2000, live specimens. A–D. G. murphyi Huber sp. n.; male and female with egg sac from W of Cañas; female with egg-sac from near Playa Iguanita, and female in web (in glass vial) from near Playa Iguanita. E–F. G. gabito Huber sp. n.; male and female with egg sac from Santa Marta. G–H. G. spiniphila Huber, 2020; male and female with egg sac from S of Riohacha. I. G. spiniphila; male from ESE of Pueblo Bello.

FIG. 3. Galapa spp., male chelicerae, frontal views. Note unmodified main segments (except for stridulatory files) and processes on fangs (arrows). A. G. murphyi Huber sp. n. from Costa Rica, near Playa Iguanita, ZFMK Ar 24224. B. G. spiniphila Huber, 2020 from Colombia, near Papayal, ZFMK Ar 24221. Scale bar: 0.1 mm.

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. 13. Galapa gabito Huber sp. n., from Colombia, Santa Marta. A. Stridulatory file on right male chelicera. B. Left female chelicera (and palp), showing absence of stridulatory file. C. Right male cheliceral fang with process (arrow), distal view. D. Male sternal hump. E. Male gonopore with epiandrous spigots. F. Female ALS. Scale bars: 10 µm (A, C–F), 20 µm (B).

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. 14. Galapa gabito Huber sp. n., from Colombia, Santa Marta. A–D. Right male palp in retrolateral to dorsal views. E. Male palpal tarsal organ. F. Female palpal tarsal organ (and neighboring sensilla). Abbreviations: b, genital bulb; da, distal apophysis of genital bulb; dp, dorsal process of procursus; pr, procursus; rp, retrolateral-distal process of procursus; ta, tarsus; to, tarsal organ. Scale bars: 100 µm (A–D), 2 µm (E, F).

FIG. 21. Galapa spiniphila Huber, 2020, male from Colombia, near Papayal. A–C. Right palp, retrolateral to dorsal views. D–F. Left palp, prolateral-ventral to prolateral-dorsal views. Abbreviations: b, genital bulb; da, distal apophysis of genital bulb; dp, dorsal process of procursus; pr, procursus; ra, retrolateral-dorsal apophysis of genital bulb; rp, retrolateral-distal process of procursus; sd, sperm duct opening; to, tarsal organ; va, ventral apophyses of genital bulb. Scale bars: 100 µm.

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. 16. Galapa gabito Huber sp. n.; females from Colombia, Santa Marta, ZFMK Ar 24219. A, B. Abdomens, ventral views. C, E. Cleared internal genitalia, ventral views. D, F. Same as preceding, dorsal views; arrow points at distinctive sclerite in ventral wall of uterus externus.Abbreviations: aep, anterior (main) epigynal plate; pep, posterior epigynal plate. Scale bars: 0.2 mm.

FIG. 24. Galapa spiniphila Huber, 2020; female abdomens, ventral views, and cleared female genitalia, ventral and dorsal views; arrows point at distinctive median membranous processes. A, D, E. Papayal morph, from Colombia, Papayal, ZFMK Ar 24221. B, F, G. Riohacha morph, from Colombia, Riohacha, ZFMK Ar 24220. C, H, I. Pueblo Bello morph, from Colombia, ESE of Pueblo Bello, ZFMK Ar 24222. Abbreviations: aep, anterior (main) epigynal plate; pep, posterior epigynal plate. Scale bars: 0.2 mm.

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. 20. Galapa spiniphila Huber, 2020, from Colombia, near Papayal. A. Male prosoma, frontal view. B. Female ocular area, frontal-dorsal view. C. Stridulatory file on right male chelicera. D. Stridulatory pick on male palpal femur. E. Male gonopore. F. Epigynum, ventral view.Abbreviations: aep, anterior (main) epigynal plate; pep, posterior epigynal plate. Scale bars: 100 µm (A, F), 20 µm (B, E), 10 µm (C), 2 µm (D).

FIG. 27. Galapa murphyi Huber sp. n., from Costa Rica, near Playa Iguanita. A, B. Male prosoma, frontal and lateral views. C. Male ocular area and clypeus, oblique frontal view. D. Female ocular area and clypeus, lateral view. E. Process on right male cheliceral fang. F. Stridulatory file on left male chelicera. G. Lateral side of left female chelicera, showing absence of stridulatory file. Scale bars: 100 µm (A–D), 10 µm (E–G).

FIG. 28. Galapa murphyi Huber sp. n., from Costa Rica, near Playa Iguanita. A. Male ALS and PMS. B, C. Female ALS and PMS. D. Epigynum, ventral view. E, F. Male gonopores of two specimens, ventral views. Abbreviations: aep, anterior (main) epigynal plate; ALS, anterior lateral spinneret; pep, posterior epigynal plate; PMS, posterior median spinneret. Scale bars: 10 µm (A–C, E, F), 100 µm (D).

FIG. 22. Galapa spiniphila Huber, 2020, from Colombia, near Papayal. A, B. Male ALS and PMS. C. Female spinnerets. D. Female ALS and PMS. E. Tip of right female tarsus 1, prolateral view. F. Tip of right male tarsus 3, prolateral view. Abbreviations:ALS, anterior lateral spinneret; PLS, posterior lateral spinneret; PMS, posterior median spinneret. Scale bars: 10 µm (A, B, D–F), 20 µm (C).

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. 23. Galapa spiniphila Huber, 2020, from Colombia, near Papayal. A. Right male tibia 2, prolateral view, showing regular mechanoreceptors and sexually dimorphic ‘short vertical hairs’. B. Right male tibia 1, prolateral view, showing sexually dimorphic ‘short vertical hairs’ (and basis of regular mechanoreceptor). C. Trichobothrium on left male metatarsus 2. D. Male palpal tarsal organ. E. Tarsal organ on left female tarsus 3. F. Cuticular plate (and basis of regular mechanoreceptor) on female femur 4. G. Rimmed pore (and basis of regular mechanoreceptor) on left female metatarsus 3. Scale bars: 10 µm (A, C, F), 2 µm (B, D, E, G).

FIG. 29. Galapa murphyi Huber sp. n., from Costa Rica, near Playa Iguanita. A–D. Left male palp, retrolateral-dorsal to prolateral ventral views; arrow in D points at prolateral distal apophysis. E. Male palpal tarsal organ. F. Tip of female palp, showing tarsal organ and subterminal invagination (arrow). Abbreviations: b, genital bulb; rp, retrolateral-distal process of procursus; sd, sperm duct opening; to, tarsal organ (covered by dirt). Scale bars: 100 µm (A–D), 2 µm (E, F).

FIG. 25. Galapa murphyi Huber sp. n.; from Costa Rica, near Playa Iguanita, ZFMK Ar 24224. Left male palp in prolateral (A), dorsal (B), and retrolateral (C) views; arrow in A points at prolateral distal apophysis. Abbreviations: da, distal apophysis of genital bulb; dp, dorsal process of procursus; pr, procursus; rp, retrolateral-distal process of procursus. Scale bar: 0.2 mm.

FIG. 17. Galapa spiniphila Huber, 2020; ‘Papayal morph’ from Colombia, Papayal, ZFMK Ar 24221. Left male palp in prolateral (A), dorsal (B), and retrolateral (C) views. Abbreviations: da, distal apophysis of genital bulb; ra, retrolateral-dorsal apophysis of genital bulb; rp, retrolateral-distal process of procursus; va, ventral apophyses of genital bulb. Scale bar: 0.2 mm.

FIG. 12. Galapa gabito Huber sp. n.; from Colombia, Santa Marta, ZFMK Ar 24219. Left male palp in prolateral (A), dorsal (B), and retrolateral (C) views; arrow in B points at prolateral distal apophysis. Abbreviations: b, genital bulb; c, coxa; da, distal apophysis of genital bulb; dp, dorsal process of procursus; f, femur; pa, patella; pr, procursus; rp, retrolateral-distal process of procursus; ta, tarsus; ti, tibia; tr, trochanter. Scale bar: 0.2 mm.

FIG. 15. Galapa gabito Huber sp. n., from Colombia, Santa Marta. A, B. Sexually dimorphic ‘short vertical hairs’ on right male tibiae 1 and 2. C. Trichobothrium on male metatarsus 4. D. Cuticular plate (and basis of regular mechanoreceptor) on male metatarsus 4. E. Rimmed pore on male tarsus 3. F. Tip of right female tarsus 2, prolateral view (arrows: putative chemoreceptors). Scale bars: 10 µm (A–C, F), 2 µm (D, E).

FIG. 30. Galapa murphyi Huber sp. n., from Costa Rica, near Playa Iguanita. A. ‘Short vertical hairs’ on right male tibia 1, prolateral view. B. Distal end of right male metatarsus 1, prolateral view, showing putative chemoreceptors (arrows). C. Putative chemoreceptor on male metatarsus 4, retrolateral view. D. Basis of trichobothrium on male tibia 4. E. Basis of trichobothrium on left male metatarsus 3, together with cuticular plate (arrow) and regular mechanoreceptor. F. Tip of left male tarsus 2, retrolateral view. G. Tip of left female tarsus 3, retrolateral view. H. Tip of left female tarsus 4, retrolateral view. Scale bars: 10 µm (A, B, E–H), 2 µm (C, D).

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. 31. Galapa murphyi Huber sp. n., from Costa Rica, near Playa Iguanita. A. Tarsal organ on left male tarsus 1. B, C. Tarsal organ and regular mechanoreceptors on left male tarsus 2; arrow points at slit sensillum. D. Tarsal organ on left male tarsus 4. E. Tarsal organ on left female tarsus 4. F. Cuticular plate and rimmed pore (and basis of regular mechanoreceptor) on left male metatarsus 4, dorsal view. Scale bars: 2 µm (A–C, E), 1 µm (D), 10 µm (F).

FIG. 32. Galapa murphyi Huber sp. n.; female abdomens, ventral views, and cleared female genitalia, ventral and dorsal views. A, B, D–G. Two specimens from Costa Rica, near Playa Iguanita, ZFMK Ar 24224. C, H, I. From 2 km NW of Cañas, ZFMK Ar 24226. Scale bars: 0.2 mm.

FIG. 1. Neighbor-joining tree of CO1 sequences of Galapa Huber analyzed using the Kimura 2-parameter model; numbers on the branches are bootstrap supports from 500 replications (%). Shown is only the ingroup. For the complete tree including outgroups, see Supplementary File, Fig. S1. Live spider: Galapa bella (Gertsch & Peck, 1992); male from Santa Cruz, near Garrapatero Beach.

FIG. 4. Known distribution of Galapa Huber, 2000.

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.