Raveniola Zonstein 1987
Creators: name: Zonstein, Sergei L.
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Arachnida
Araneae
Nemesiidae
Raveniola

description: Raveniola Zonstein, 1987
Raveniola Zonstein, 1987: 1014.
Brachythele [part] – Ausserer 1871: 177. — Simon 1891: 304. — Caporiacco 1934: 113. — Spassky 1937: 363–367; 1952: 193. — Spassky & Minenkova 1940: 140. — Charitonov 1946: 19; 1948: 135. — Brignoli 1972: 409. — Mkheidze 1983: 155. — Fet 1984: 37. — Zonstein 1984b: 41–45; 1985: 158–160.
Anemesia [part] – Denis 1958: 82.
Raveniola – Zonstein & Marusik 2012: 74. — Li & Zonstein 2015: 3. — Zonstein et al. 2018: 5. — Zonstein 2021: 209.
Type species
Brachythele virgata Simon, 1891, by original designation.
Diagnostic characters
According to Zonstein et al. (2018: 5), Raveniola and Sinopesa share the presence of two (sometimes three) retroventral megaspines located sequentially on tibia I in males (a unique position among male nemesiids) and paired spermathecae in females, each two-branched (or with a lateral diverticulum); a maxillary serrula and preening combs are absent. Raveniola differs from Sinopesa chiefly by having a noticeably longer and denser leg scopula (vs a short and rare scopula in the latter genus), and a developed leg and carapace setation.
General characteristics of Central Asian species
It should be noted that no common characters shared only by Central Asian Raveniola spp., and distinguishing these species from all the Western and Eastern Asian congeners, were found. At the same time, in three Central Asian species groups based on R. caudata, R. concolor and R. diluta sp. nov., each of them possesses at least one unique group trait (see the corresponding group diagnoses). Regarding the remaining group based on R. virgata, the members differ from most other species but show some resemblance to several extra-regional congeners, viz. R. niedermeyeri and R. vonwicki from Iran, and R. hebeinica from China (Figs 444, 448, 459, 538, 540, 545, cf. Zhu et al. 1999: figs 1–10; Zonstein & Marusik 2012: fig. 39; Zonstein et al. 2018: figs 158, 164, 185, 197, 210–212).
Morphological peculiarities of Central Asian Raveniola species
HABITUS. The studied spiders are mostly small or medium-sized nemesiids with a carapace length of 3–12 mm.
CEPHALOTHORAX. Carapace broadly oval and hirsute, with cephalic part slightly to noticeably higher than thoracic part. Male thoracic fovea very short, pit-like, T-shaped, or gently recurved. Female thoracic fovea short and narrow, nearly straight in most species, or very gently arched (procurved or recurved) in some species. Eye tubercle moderately elevated (better developed than in species from Western Asia). Chelicerae in some species with weak rastellum composed of spike-shaped setae. Maxillae generally with numerous cuspules confined to probasal edge; maxillary serrula absent, as in other Raveniola spp.
STRUCTURES OF LEGS I–IV. Leg scopula varies from dense and moderately long to thin and short. Scopula distal on metatarsi I–II, generally entire on tarsi I and II, divided by setae or absent on tarsi III and IV; females also with usually entire scopula on palpal tarsus. Tarsi I–IV without spines. PTC I–IV biserially and densely dentate (females possess lesser dentate paired claws than conspecific males), unpaired claw small, curved and bare.
MALE PALP. Tibia long, fairly slender and spinose. Cymbium with or without spines. Copulatory bulb inserted at apical part of cymbium. Embolus tapering or broadly tipped, with or without keels and ridges, varying in length from relatively short to long and slender.
SPERMATHECAE. A pair of wide or narrow spermathecae, each with two distinct branches. In many species, the spermathecal base and the inner branch are poorly differentiated from each other and together they form a continuous spermathecal trunk. Long or short outer branch (lateral diverticulum) always distinct.
SPINNERETS. Two pairs or one pair of spinnerets. PMS vary from medium-sized to very small, with or without functional spigots, or absent in some species. Apical segment of PLS ranges from triangular (most species) to digitiform or even elongate in some species.
Species included
In view of the new congeners included herein, Raveniola currently comprises 66 species; 29 of them occur in Central Asia: R. afghana sp. nov., R. alajensis sp. nov., R. caudata Zonstein, 2009, R. concolor Zonstein, 2000, R. cucullata sp. nov., R. diluta sp. nov., R. dolosa sp. nov., R. fedotovi (Charitonov, 1946), R. ferghanensis (Zonstein, 1984), R. hirta sp. nov., R. ignobilis sp. nov., R. inopinata sp. nov., R. insolita sp. nov., R. karategensis sp. nov., R. kirgizica sp. nov., R. kopetdaghensis (Fet, 1984), R. mikhailovi Zonstein, 2021, R. nenilini sp. nov., R. ornata sp. nov., R. ornatula sp. nov., R. ovchinnikovi sp. nov., R. pallens sp. nov., R. pamira sp. nov., R. redikorzevi (Spassky, 1937), R. sororcula sp. nov., R. tarabaevi sp. nov., R. virgata (Simon, 1891), R. vulpina sp. nov., and R. zyuzini sp. nov.
Species grouping
To assist with identifications, the species treated here are assigned to four species groups, according chiefly to the structure of the spinnerets and the male and female copulatory organs. These assignments are preliminary, because males and females in some species are unknown and they are not based on a phylogenetic grouping, though some of the groups may indeed reflect phylogenetic relationships.
Distribution and ecology
Within Central Asia, representatives of Raveniola are distributed from the western part of Kopetdagh (Turkmenistan) in the west, through the Badkhyz Plateau and Hindu-Koh Mts (passing and skirting the desert plains of the huge Turan Depression), to southeastern Kazakhstan in the north-east and to Ladakh (northwestern India) in the south-east (see Fig. 747). Due to the greater diversity of Central Asian landscapes, compared to Western Asian ones, there is a wider range of inhabited biotopes (including semi-deserts and highlands) and of the corresponding ecological strategies and adaptations. Like Western Asian congeners, most Central Asian Raveniola spp. use natural retreats (usually cavities under rocks or abandoned burrows of other animals) to build primitive burrow-like dwellings, sparsely covered with silk. However, some species inhabiting lowland arid bioms or, conversely, highland biotopes, are found to be true bothrobiont spiders digging deep open burrows with silk lining or without it.
Key to the Central Asian species groups of Raveniola Zonstein, 1987
Males
1. Embolus broadly tipped (Figs 379–384, 466–468). Apical segment of PLS elongate (Figs 555– 557) ............................................................................................................................... caudata group
– Embolus with well-defined thin and curved subapical part (Figs 385–465, 469–478). Apical segment of PLS triangular (as in Figs 563, 568, 593, 605, 609, 614) or shortly digitiform (as in Figs 581, 604, 612) ................................................................................................................................................... 2
2. Embolus needle-shaped and evenly tapering, with subapical part very gently curved and lacking bends and keels, as in Figs 439–465, 478 ....................................................................... virgata group
– Embolus with proximal and apical parts separated by bend (often provided with keel), as in Figs 385– 438, 469–477 ..................................................................................................................................... 3
3. Cymbium shorter (Figs 352–364). Narrowly tapering proximal part of embolus considerably longer than its apical part (Figs 385–428). PMS present (Figs 560, 563, 565, 571, 573, 575, 584) ............................................................................................................................. concolor group
– Cymbium longer (Figs 365–369). Broadly tapering proximal part of embolus slightly longer than its apical part (Figs 429–438). PMS absent (Figs 589, 591, 585) ......................................... diluta group
Females
1. Apical segment of PLS elongate (as in Fig. 558) ......................................................... caudata group
– Apical segment of PLS triangular (as in Figs 559, 561, 562, 567, 569, 572, 586, 588, 594, 600, 607, 615, 618) or shortly digitiform (Figs 578, 579, 582)......................................................................... 2
2. PMS relatively large (Figs 566, 576, 585), medium-sized (Figs 564, 572, 574, 587) or small (Figs 568, 570, 578–580, 582–583), but always with apical spigots (as in Figs 482–483). Numerous (> 25) maxillary cuspules arranged in a wide triangular area (Figs 230–242). Spermathecae as in Figs 489–525 ............................................................................................................... concolor group
– PMS tiny (Figs 599, 603, 611, 613, 615, 617), without spigots (as in Figs 485–486), or absent (as in Figs 592, 594). Less numerous (<25) cuspules spread along probasal maxillary heel (Figs 243– 255). Spermathecae different (see Figs 526–554) ............................................................................. 3
3. PMS absent. Spermathecae with wide bases and short robust inner branches (Figs 526– 533) .................................................................................................................................. diluta group
– PMS usually present (absent in R. kopetdaghensis). Spermathecae with narrow bases; shape of inner branch differs (Figs 534–554)......................................................................................... virgata group
Data on natural history
Habitats
Depending on the altitude, prevailing landscape, precipitation regime and thermal conditions, all inhabited biotopes can be conditionally divided into three main zonal types. The first of these includes a harsh and periodically dry zone of foothills and low mountain ridges limited by lower and upper boundaries at altitudes of 450–500 m and 1000–1500 m, respectively. These biotopes are located mostly on loess substrate, on slopes covered with different types of xerophilic drought-resistant vegetation: from ephemeral semi-deserts to dense shrubland and sparse woodland composed of low sclerophyll trees (Figs 619–626, 715).
Similar to the Western Asian species of Raveniola, a higher level of species diversity in Central Asian congeners occurs in the most moist, mild and favorable midland-mountain forest zone (hosting 18 of the 29 regional species). However, compared with the western part of Asia, both the lower and the upper borders of this zone in the central part of the continent are at a higher altitude (which can be explained by the present-day continental climate of the region). Depending on the specific subregion, this zone can comprise a single and continuous area (as for example in southern Kyrgyzstan; Figs 720–721, 731), or it can represent a mozaic of more or less isolated fragments (like those in Tajikistan and southern Uzbekistan, shown in Figs 631–632, 699–700, 708). Within Central Asia, the lower boundary of this zone is at an altitude of at least 750 m (in the western Kopetdagh Mts), but usually 1000–1500 m a.s.l.; the corresponding upper limit is confined to 2000–2300 m a.s.l.
Finally, the third group of biotopes is represented by highland landscapes, with juniper and coniferous forests, subalpine and alpine meadows and meadow-steppes on the rocky slopes (Figs 627–628, 651– 654, 677–679, 682, 717–718, 722, 738). The lower edge of this zone is located at an altitude 2000–2300 m a.s.l. The highest altitudinal record for Central Asian Raveniola spp. is registered in this zone at an altitude of 3400–3700 m in Darvaz Mts, Tajikistan (Andreeva 1975; 1976; under Brachythele sp.).
Burrows and retreats
Sampling and direct observations on the ecology of Central Asian Raveniola spp. in the natural environment have shown that the majority of species do not dig their own burrows. Rather, these spiders exploit different natural refuges to hide themselves. In most cases, such refuges comprise cavities and hollows in the soil under stones, where the spiders thinly and scarcely line the bottom and walls with silk (Figs 635–642, 647–650, 683–698, 705–706, 733–734). Several species, e.g., Raveniola cucullata sp. nov., are able to further deepen less suitable refuges (Figs 633–634). In contrast, some adult females belonging to R. mikhailovi, R. nenilini sp. nov., R. virgata and R. vulpina sp. nov., when inhabiting moist slopes that are devoid of suitable stones and logs (as shown in Figs 724–726, 731–732), can settle using natural open depressions adjacent to tree trunks.
The three species of the caudata group are mostly known from wandering males, which have occasionally been found under stones, used as temporary shelter during daytime. The only known female of Raveniola redikorzevi, however, as well as all the known juvenuiles of R. caudata and R. redikorzevi, were collected from abandoned burrows of gerbils (Rhombomys opimus (Lichtenstein, 1823), Meriones spp.) and tortoises (Agrionemys horsfieldii (Grey, 1844)). Within the virgata species group, R. ovchinnikovi has also been found to hide deeply inside abandoned burrows of small vertebrate animals. Another uncommon econiche settled by the latter species is that of the natural deep crevices in outcrops of loess substrate. Finally, all hand-collected specimens of R. fedotovi were found inhabiting screes in woodlands under the tree canopy (Figs 708–710).
Only a few Central Asian species of Raveniola are known to dig their own burrows. It is noteworthy that these burrowing species occurred closer to either the lower or the upper habitat limits of the Central Asian congeners, but are not found in the most favorable environments of the mid-mountain zone. The only species that inhabits the loess foothills of Western Tien Shan (Fig. 715), with their long dry summer period, is R. ferghanensis, known as a strictly obligate burrower. In contrast, the four highland members of the concolor group, R. afghana sp. nov., R. alajensis sp. nov., R. hirta, sp. nov. and R. karategensis sp. nov., which inhabit the subalpine juniper forests, subalpine and alpine meadows, and meadow-steppes at an altitude of 1900–3700 m, have also been collected exclusively from their burrows. Raveniola insolita sp. nov., known only from a single male, which was collected at an altitude of 3300–3400 m, can probably also be assigned to the members of the latter subgroup.
Unlike the similarly unprotected holes dug and used by members of the obligate burrowing Central Asian genus Anemesia, the burrows of a few bothrobiont Raveniola spp. appear to be arranged more simply. Compared with the burrow structure found in Anemesia spp. (see Zonstein 2018b: figs 330–367), these burrows are almost similarly deep (ca 30–40 cm in length), but are noticeably narrower in their median part and much more scarcely silk lined (except for the terminal living chamber, which is more densely lined). The open entrance mostly lacks the silk lining and resembles a hole used by other terrestrial arthropods (the bothrobiont coleopterans, e.g., Lethrus spp., or woodlice; see Figs 657, 716). Sometimes this entrance is partially camouflaged by the surrounding detritus or vegetation (Figs 655–656, 661). A more complex variant of an entrance arrangement was observed in R. karategensis sp. nov., in which the burrow mouth was visibly silk lined and provided with a low rim (Figs 659–665). The expanded living chamber always has a horizontal extension, as shown in Fig. 666. In all cases, no lateral chambers connecting the burrow shaft with the soil surface were observed.
Phenology
Data on the phenology of the congeners are sparse and based completely on fragmentary field observations. The collecting data indicate that in localities with a dry summer period the wandering adult Raveniola males occur in April–May (the most wet and favourable period). In some species inhabiting this type of biotope, a second appearance of wandering males, connected with the end of a dry period in October– November, can be observed (particularly, in R. cucullata sp. nov., R. ferghanensis, and R. kopetdaghensis). Several congeners, such as R. ignobilis sp. nov., R. subornata sp. nov. and R. ovchinnikovi sp. nov., are known as species with males collected only in October. In highland members of the genus, e.g., in R. alajensis sp. nov. and R. hirta sp. nov., the peak of their activity, including the presence of wandering adult males, unsurprisingly moves into the mid-summer (July). Males of the most mesophilic species, like R. virgata, within the humid areas (such as the midlands of the Ferghana Mts in the environs of Arslanbob, with summer rainfalls) can be almost evenly found from mid-April to late October.
Females with egg sacs can be found in July (R. alajensis sp. nov., R. cucullata sp. nov., R. dolosa sp. nov., R. karategensis sp. nov., R. mikhailovi, R. pamira sp. nov., R. sororcula sp. nov. and R. tarabaevi sp. nov.), or in July and August (R. virgata, R. vulpina sp. nov.). The egg sac usually reaches 12–19 mm in diameter and contais 25– 45 eggs.
Feeding
Some currently incomplete data, which nevertheless appear to fit the general trends, have been obtained for only two Central Asian species of the genus: Raveniola ferghanensis and R. virgata. These are only generalized data on the composition of the prey remains; no quantitative counts were made. The corresponding data for other regional congeners are fragmentary and not comparable to each other, and thus are not considered below.
In Raveniola ferghanensis, a major part of the “kitchen leftovers” retrieved from the bottom of the investigated burrows was represented by the head capsules and other fragmented parts of foraging ants (Hymenoptera, Formicidae), including the wandering predatory foragers Catagliphus aenescens (Nylander, 1849), and the marching carpophagous ants Messor muticus (Nylander, 1849) and M. aralocaspius (Ruzsky, 1902). The minor part of the chitinous remains, observed as leftovers in most of the studied burrows, belonged to burrowing arthropods, which share these biotopes with R. ferghanensis: the xerophilic terrestrial woodlice Hemilepistus fedtschenkoi (Uljanin, 1874) (Isopoda, Agnaridae) and the colonial coleopterans Lethrus spp. (Coleoptera, Geotrupidae). The latter remains tended to belong to either L. sulcipennis Kraatz, 1883 or L. micronatus Semenov, 1894, or both sympatric species, which inhabit the same biotopes. Finally, some of the burrows contained remains of Madotrogus sp. aff. ferganensis (Protzenko, 1962) (Coleoptera, Scarabaeidae), as well as of some other unidentified representatives of Coleoptera.
Regarding Raveniola virgata, there are somewhat more complete data on the composition of their prey. Similar to the above, most of the prey remains were represented by a few ant species (Hymenoptera, Formicidae), but in this case by ants wandering through or nesting within the forest floor: Camponotus reichardti K. Arnoldi, 1967, Messor rufus Santschi, 1923 and Myrmica juglandeti K. Arnoldi, 1976. Most of the other collected and studied remains belonged to the following representatives of the Coleoptera: Carabidae: Chilotomus sp. aff. uzgentensis Shauberger, 1932, Eocarterus uzgentensis Heyden, 1884, Harpalus sp., Leistus sp. aff. ferganensis Semenov & Znojko, 1928, Poecilus sp., Pterostichus sp. aff. sodalicius Heyden, 1885, Trechus sp.; Curculionidae: Asiodonus sp., Polydrosus sp.; Elateridae: Selastomus sp.; Glaphyridae: Amphicoma sp.; Staphylinidae: Philonthus sp.; Tenebrionidae: Laena sp., Zophohelops tiro (Reitter, 1902). The remains of Ectobius delicatulus Bei-Bienko, 1950 (Blattoidea: Ectobiidae) were more frequent, while fragments of Hessebius plumatus Zalesskaya, 1978, Monotarsobium sp. (Chilopoda, Lithobiidae) and remnants of Dysdera sp. aff. arnoldii Charitonov, 1956 (Araneae, Dysderidae) were found in a few isolated cases.
Mating
Regarding Central Asian Raveniola spp., fairly satisfactory data are available only for representatives of R. virgata kept in captivity (for details see Zonstein 2002c). The corresponding observations were carried out on October 20–22, 1992. To imitate the natural environment, observations were made at night, under dim lighting, in large cages for each pair, allowing greater mobility of males and females. Each female was placed in its cage one day before the male, enabling the females to find or to dig a refuge (which mostly resembled an open cavity between lumps of soil). After introducing a male into each cage, the sequence of events in most cases was as follows.
Having discovered the entrance to the female’s refuge, the male began to tap with the tips of the palps on the substrate, demonstrating a short courtship stage. When the female appeared, within a few seconds the male made several pedalling movements with the palps (resembling the pedalling of a cyclist). The male then stretched forward its first pair of legs, moved towards the female and approached her (see Figs 739–741). This is followed by touching the female with the tips of the male’s legs I for 3–4 seconds (Fig. 742). Concurrently, the male’s legs II were also raised off the ground surface and began to vibrate, tapping the female’s legs.
A few seconds later, the male used its megaspines to grab the trochanters or femora of the female’s palps, gripping them on their proventral side (Figs 743–744). The male then bent his first pair of legs at the tibiometatarsal joint and extended them upward. The male thereby closed the clamps, clasped the female’s palps, and lifted the female’s cephalothorax upward, so that the latter formed an angle with her abdomen, sometimes reaching almost 90° (Figs 745–746). The entire operation lasted no more than 2–5 seconds. Following attachment, one of the emboli entered the spermathecal openings.
During each recorded phase of mating, the longest of them was the copulation process itself (from the initial insertion of the embolus into the copulatory organs of the female until its final removal). This stage is considered hereafter as the duration of copulation. All other stages – approach, initiation, coupling and uncoupling of the partners – took several seconds each.
The data obtained from laboratory observations on the copulation behavior in 20 pairs of R. virgata indicate that the duration of a basic insertion/removal act in this species varies from 27 seconds to 13 min. and 20 sec., averaging 6 min. and 13.2 sec. Usually, the entire copulation process ended with this single act. However, in six pairs a continuation was observed, associated with a one-time change of the involved palp. Even more rarely (three observations), a quadruple insertion of the emboli was detected. In the latter case, the total duration of copulation, which averaged about 10 min. for the examined specimens, increased up to 14–19 minutes. During copulation, the male continued to move towards the female, turning her onto her dorsal side. Having completed copulation, the male removed the involved embolus. Then, pressing on the female palpal femora, the male knocked the female over, climbing over her before the female could roll back.
According to a few observations of captive representatives of R. cucullata sp. nov., R. ferghanensis and R. nenilini sp. nov. (one, one, and two observed but not documented encounters, respectively), the courtship and copulation in these species occured in a similar way. In the natural environment, a copulating pair of R. virgata has incidentally been observed only once (see Zonstein 1987). In addition, this took place during the daytime, which was somewhat surprising, because such behavior cannot be considered characteristic for either nemesiids, or for mygalomorph spiders in general.
Predators
All known data on the predators interacting with and feeding on the Central Asian species of Raveniola refer only to a few taxa of spider wasps (Hymenoptera, Pompilidae). The pompilids that hunt and prey on these members of Raveniola belong to the pompiline genera Pareiocurgus Haupt, 1962 and Pamirospila Wolf, 1970. Pareiocurgus latigena (F. Morawitz, 1893) is known from Uzbekistan, Tajikistan and southern Kyrgyzstan. These wasps feed on several species of burrowing spiders, including R. ferghanensis and representatives of Anemesia (Zonstein 2000b). All five species of the endemic Central Asian genus Pamirospila (surveyed by Zonstein 2000b, 2002a, 2002b) are probably specialized predators feeding only on Raveniola spp. Pamirospila is confined to the same range as that of Raveniola in Central Asia. Additionally, at least twice, females of P. pamira (Haupt, 1930) have each been observed leaving a burrow of R. alajensis sp. nov., with the living chamber littered with soil lumps and with a paralyzed spider inside. A similar interaction has also been noted for R. hirta sp. nov. (Zonstein 2000b).
description: Published as part of Zonstein, Sergei L., 2024, A revision of the spider genus Raveniola (Araneae, Nemesiidae). II. Species from Central Asia, pp. 1-185 in European Journal of Taxonomy 967 on pages 8-87, DOI: 10.5852/ejt.2024.967.2699, http://zenodo.org/record/13990819