Priscula Simon, 1893

Huber, Bernhard A., Meng, Guanliang, Dupérré, Nadine, Astrin, Jonas & Herrera, Mauricio, 2023, Andean giants: Priscula spiders from Ecuador, with notes on species groups and egg-sac troglomorphism (Araneae: Pholcidae), European Journal of Taxonomy 909, pp. 1-63 : 10-15

Genus Priscula Simon, 1893

General notes

The genus was revised in Huber (2000) and the diagnosis and general description given there are still largely valid (see below for amendments of description). Since then, the genus has received little attention, with only two further publications contributing to our knowledge of the group. Huber & Villarreal (2020) reported new species from Venezuela, and Huber (2014) added a few records for P. binghamae (Chamberlin, 1916) from Argentina.

The species described in Huber & Villarreal (2020) and the new species described below largely fit the genus description given in Huber (2000). The following amendments complement the genus description: 1) ocular area in males sometimes with strong hair brushes between eye triads; (2) male clypeus unmodified in shape, but rim often more strongly sclerotized than in female; (3) abdomen ventrally in front of spinnerets sometimes with sclerite or pair of sclerites; (4) male chelicerae consistently with whitish lateral area; (5) male palpal femur sometimes with ventral process at about half length; (6) main bulbal process not always spiraling but sometimes of simpler shape; (7) tibia 1 L/d: 23–73; (8) prolateral trichobothrium on tibia 1 present.

Molecular analyses

The results of the molecular analyses are shown in Figs 1–2 and in Supplementary Figs S1–S 4 and Supplementary Table S2 . Details are presented in the Species groups section below (phylogenetic aspects) as well as within the individual species descriptions (barcoding aspects).

Species groups

The relationships of Priscula to other genera were not the focus of the present study and will soon be addressed using molecular (UCE) data (G. Meng, B.A. Huber, L. Podsiadlowski, unpubl. data). Within Priscula , our molecular data suggest five species groups ( Figs 1–2 ) that are consistently and sometimes highly supported. For morphological support for these groups and for possible assignments of species not included in the molecular dataset, see Discussion.

gularis group

This group includes the type species P. gularis Simon, 1893 , and three of the newly described species: P. azuay sp. nov., P. espejoi sp. nov., and P. llaviucu sp. nov. It always received high support (SHaLRT supports: 92–100) and was in most analyses (except when using TrimAl and Gblocks) resolved as the sister of the other four groups (see Fig. S2 ). Internal relationships varied but two undescribed species (“ P. Ecu5” and “ P. Dup55”) were consistently resolved either as paraphyletic ‘basal’ species or together as sister of the remaining species. Among the latter, P. azuay was again consistently resolved as sister to the rest. All sequenced species in this group are from Ecuador.

binghamae group

This group includes the southernmost known species, P. binghamae , an undescribed species from Peru (“ P. Astr07”), and three of the newly described species from Ecuador: P. esmeraldas sp. nov., P. chapintza sp. nov., and P. pastaza sp. nov. The group received reasonable to high support (78–94) and was in most analyses resolved as the sister of the three following groups; only TrimAl and Gblocks resolved the binghamae group as sister to all other groups. The three species from Ecuador were always resolved as monophyletic (79–96), always in the same topology: P. esmeraldas +( P. chapintza + P. pastaza ).

limonensis group

The species included in this group are from the Cordillera de la Costa and the Cordillera de Mérida in Venezuela, and from the Island of Trinidad. The group received reasonable to high support (86– 100); it always formed a monophylum with the following two groups (79–84), as their sister. Internal relationships were consistently resolved in the same topology.

salmeronica group

The species included in this group are restricted to Venezuela, where they occur in the Cordillera de la Costa and in the Cordillera de Mérida. The group received reasonable to high support (86–98) and always formed a monophylum with the andinensis group (82–96). Internal relationships varied, except that P. salmeronica González-Sponga, 1999 was consistently resolved as sister to an undescribed species (“ P. Ven02/100-33”). andinensis group

This group includes two of the newly described species: P. bonita sp. nov. and P. lumbaqui sp. nov. Geographically, it ranges from the eastern side of the Central Andes in Ecuador to the Cordillera de la Costa in Venezuela. The group received modest to high support in most analyses (81–99; only TrimAl in partitioned analysis lower: 72) and was consistently resolved as sister to the salmeronica group (82– 96). Internal relationships varied, except that P. venezuelana Simon, 1893 was consistently resolved as sister to an undescribed Venezuelan species (“ P. sp.-light”) (84–100), and P. bolivari Huber, 2020 was consistently resolved as sister to P. andinensis González-Sponga, 1999 (mostly 78–87; only TrimAl in unpartitioned analysis lower: 33). The two new Ecuadorian species were never resolved as sister taxa.

Distribution

Priscula is a tropical Andean genus ( Figs 3–4 ), ranging from northern Argentina to the Island of Trinidad (whose Northern Range is an outlier of the Venezuelan Andes). Many records are from high elevations (79% of all known records> 1000 m a.s.l.; 32%> 2000 m). A notable geographic outlier is P. taruma Huber, 2000 , supposedly collected in Guyana, East Berbice-Corentyne, “Canje Ikuruwa River”. In the original description ( Huber 2000), the label coordinates were incorrectly shown as degrees and minutes, while in fact they should be read as decimal degrees: 5.70° N, 57.50° W (which marks a spot between Canje River and Ikuruwa Lake; approximately 10–20 m a.s.l.). This species is known from a single male specimen, and it continues to be the only record of Priscula from the entire Guyana Shield. This record might thus result from mislabeling and should be doubted until the presence of Priscula is confirmed from this locality or region.

Natural history

Most of the species newly described below were found in sheltered spaces like deep holes at ground level, tunnels under roads, deep within large grass tussocks, or in thick mosses covering tree trunks (see individual natural history sections below). This cryptic lifestyle is probably correlated with their general dark coloration ( Eberle et al. 2018; Figs 5–6 ). Most known Priscula species share the dark coloration and thus probably also the cryptic lifestyle (for a few known exceptions, see Discussion).Anecdotal observations (B.A. Huber, unpublished data on an unidentified species in Merenberg Reserve, Colombia) suggest that some or many of these species may be nocturnal, abandoning their hideaways in the darkness and spending the night in exposed parts of their webs. The cave-dwelling P. pastaza ( Fig. 6A–B ), by contrast, was found hanging from the center of its exposed web during the day, suggesting that visual predators account for the reclusive day-lives of forest-dwelling species. This may be related to a further observation regarding cave-dwelling versus forest-dwelling species: two P. pastaza egg-sacs contained only six and seven eggs, respectively, while egg-sacs of 15 further species contained an average of 42 eggs (data from Huber & Villarreal 2020; Huber & Eberle 2021; and herein). This relationship persisted when egg numbers were corrected for body size (female carapace width) ( Fig. 7A ): P. pastaza had by far the lowest value (4.2), followed by a Venezuelan species that lives in cave entrances ( P. acarite Huber, 2020 : 10.0); in the other 14 studied species, this value ranged from 13.5–32.7 (mean 20.7). Egg size ranged from 0.81–1.22 mm (N =16 species, 25 egg-sacs). The eggs of P. pastaza were of medium size (1.00 mm) but, corrected for body size, P. pastaza had the largest eggs ( Fig. 7B ).

Composition

The genus now includes 28 described species, most of them from Venezuela (currently 13 described species) and Ecuador (nine species). Unpublished material shows that the genus is also diverse in Colombia (only three described species) and Peru (two described species).

Figures

Fig. 1; continued in Fig. 2. Relationships of Priscula derived from an unpartitioned analysis of molecular data using IQ-Tree and the ClipKIT kpic-smart-gap trimming strategy. Numbers on the branches are SH-aLRT supports (%). The tree shows only the ingroup. For the complete tree (incl. outgroups), and for clade support using different partitioning and alignment strategies, see Supplementary Figures S1–S3. Photos on the right, from top: Priscula llaviucu Huber sp. nov.; P. espejoi Huber sp. nov.; P. binghamae (Chamberlin, 1916); P. pastaza Huber sp. nov.; P. “Tri18-11”.

Fig. 3. Known distribution of Priscula. A. Map showing all known records, including unpublished material available in collections (B.A. Huber, unpubl. data). Note that the type locality of P. taruma in Guyana is dubious (see text for details). B. Known distributions of the three species groups represented in Ecuador. Red: andinensis group; green: gularis group; blue: binghamae group; see text for further details.

Fig. 4. Known distribution of Priscula in Ecuador. A. Representatives of the gularis group. Circles: P. gularis (TL=type locality) and specimens treated herein as “P. gularis?” and “P. cf. gularis”. Squares: other Ecuadorian representatives of the gularis group. B. Representatives of the andinensis group (red) and binghamae group (blue) in Ecuador. The background colors indicate biogeographic regions of Ecuador (as far as relevant for Priscula, i.e., Andean regions from western foothill forests to eastern foothill forests), taken from Torres-Carvajal et al. (2019).

Fig. 5. Priscula spp., gularis group, live specimens. A–B. P. azuay Huber sp. nov.; male and female from Guayaquil-Cuenca, ‘loc. 2’. C–D. P. llaviucu Huber sp. nov.; male and female with egg-sac from Cajas National Park. E–F. P. cf. gularis; males from near Zhud and from near Baños. G–H. P. espejoi Huber sp. nov.; male and female with egg-sac from Guayaquil-Cuenca, ‘loc. 1’.

Fig. 6. Priscula spp., binghamae and andinensis groups, live specimens. A–B. P. pastaza Huber sp. nov.; male and female with egg-sac from Cavernas del Anzu Forest Reserve. C–D. P. bonita Huber sp. nov.; male from La Bonita-Santa Barbara and female with egg-sac from Gruta de los Tayos. E–F. P. lumbaqui Huber sp. nov.; male and female from near Lumbaqui.

Fig. 7. Egg numbers and sizes in 16 species of Priscula. A. Mean egg numbers per egg-sac corrected for body size (egg number / female carapace width in mm), in ascending order. B. Egg diameter corrected for body size (female carapace width), in same order as previous diagram. Species (number of egg sacs studied in parentheses): 1. P. pastaza Huber sp. nov. (2); 2. P. acarite (1); 3. P. “Tri18-11” (1); 4. P. ulai (2); 5. P. piapoco (1); 6. P. bonita Huber sp. nov. (2); 7. P. binghamae (2); 8. P. espejoi Huber sp. nov. (3); 9. P. salmeronica (1); 10. P. andinensis (2); 11. P. paila (2); 12. P. cf. gularis (ZFMK Ar 24091) (2); 13. P. esmeraldas Huber sp. nov. (1); 14. P. llaviucu Huber sp. nov. (1); 15. P. lumbaqui Huber sp. nov. (1); 16. P. venezuelana (2). Data from Huber & Villarreal (2020), Huber & Eberle (2021), and herein.