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- Gandanameno Lehtinen, 1967: 235. Type species Eresus spenceri Pocock, 1900.
Gandanameno contains five recognized species from eastern and southern Africa. We examined the collection holdings of several museums and most primary type specimens. The oldest available name, Eresus fumosus C. L. Koch, 1837, apparently lacks any type specimen (Lehtinen 1967: 235). We evaluated morphological variation and analyzed DNA sequences from 24 individuals based on previously published and new data. Descriptions are based on a female specimen from Tanzania (ZMUC 19970530, ZMUC) and a male from Zimbabwe (AcAT 2005/123, NCA) supplemented by collections mostly from South Africa.
Distinguished from other eresids except Dresserus by the position of the PLE which are both advanced (< 0.28) and widely spaced (PER/AER > 0.95; Fig. 9F, H); other eresids with advanced PLE (e.g., Stegodyphus, some Paradonea) have them closer together (PER/AER < 0.90) than the ALE (e.g., Figs 10B, 11F). Male further distinguished from other eresids except Dresserus by the more or less ventral-dorsal axis of the palpal bulb with the embolus encircling the ventral part (Figs 13D, E, 48A–C; proximal-ventral in other eresids with the embolus encircling the distal part, e.g., Fig. 20A–F) and conductor arising from the center of the tegulum with opposing projections covering much of the palpal bulb (Fig. 55C); distinguished from Dresserus by the lack of prominent tubercles bearing the ALE (Fig. 9F; compare with Fig. 8J) and the fringed conductor (Fig. 55C, E; smooth in Dresserus, Fig. 34D). Female further distinguished from other eresids except Dresserus and Eresus walckenaeri by the copulatory openings, which are broadly separated by hirsute cuticle (Figs 17A–C, 59A; separated by a glabrous median lobe in other eresids, e.g., Figs 16B, 29C); Gandanameno and Dresserus together distinguished from other eresids including Eresus walckenaeri by the vulva, which have the spermatheca extending anterior of the spermathecal heads, together subtended by helical copulatory ducts (Figs 17D–F, 59C; other eresids have the spermathecal head anterior, spermatheca posterior, and copulatory ducts other than helical, e.g., Fig. 29D), and by the subdivided PMS (Fig. 57C; entire in other eresids) with numerous short, conical, cylindrical gland spigots (Fig. 58E; cylindrical gland spigots absent or difficult to distinguish from aciniform gland spigots in other eresids); distinguished from Dresserus by the somewhat more prominent paired atria (Figs 17A–C, 59A; compare with Figs 16C, 37D) and possibly by having three loops of the copulatory duct (Figs 17D–F, 59C; fewer in Dresserus, although this character has been investigated in few Dresserus species, Figs 16F, 37E). Both sexes usually distinguished from Dresserus by the two part cribellum (Figs 57E, 60E, compare with Fig. 36F), although signs of the distinctive 4-part cribellum are sometimes apparent in Gandanameno.
Gandanameno are variable in several conspicuous characteristics. In the male, these include the presence or absence of a cheliceral boss (Fig. 56C–F), palp size, details of the conductor shape, and the curvature and position of the tegular sperm duct (Figs 48B, D–F, S2A–J). In the female, these include the height of the cephalic region, and the presence of cuspules of various weights on the carapace, sternum, and basal segments of legs I, II, and sometimes III (Figs 50, 52A–F, 53A–F, 54A–F), also details of the epigynum shape (Figs 17A–C, S2K, L, S3A–F, H–L). It has been noted previously that multiple forms may occur sympatrically and that intermediate combinations make species determination problematic (Tucker 1920). Indeed, in most regions where several specimens are known, a wide range of variation can be found (Fig. 50). We attempted to sequence DNA from several museum specimens. Unfortunately, most of our successes were from specimens at one end of the range of variation, i.e., specimens with a moderately to strongly raised cephalic region and abundant, heavy cuspules on the carapace, sternum, and anterior legs. The three contrasting female specimens (13-10: KwaZulu-Natal; 18-04: AcAT 2002/181; 14517) did not group together. Instead, relationships appear to be more strongly tied to geography than to morphology (Fig. 51). The genitalia of 23 out of 24 Gandanameno specimens included in the molecular phylogenetic analysis are photo-documented in the electronic supplementary materials (Figs S2A–L, S3A–L).
We looked for patterns of variation in adult female morphology. Adult female specimens are much more abundant in collections than males. We defined eight geographic regions based on two criteria: 1) concentration of specimens available to us and/or 2) type localities of Gandanameno species (Figs 49, 50). We assessed a series of characters: carapace length, carapace width, presence and strength of cuspules on the ventral surface of femur I and II, prosoma, and sternum for all specimens available from these regions. When cuspules are present on the prosoma, they always occur on the femurs, but the reverse is not always true. So the set of specimens with cuspules on the femurs is larger than and contains the set of specimens with cuspules on the prosoma. There appears to be a general trend towards greater spinulation and a higher carapace with increasing size (carapace length), but the spinulation data are fairly noisy (Fig. 50). No morphological pattern emerged to segregate specimens by region. Not all degrees of spinulation were observed in every geographic region.
Based on the combination of genetic, morphometric, and spinulation data, we see no evidence that the characters traditionally used to discriminate Gandanameno species are valid. We speculate that ontogenetic factors are responsible for the morphological variation in this genus (perhaps juvenile nutrition or post adult molting). However, we judge that the synonymy of all Gandanameno species is premature, particularly in light of the phylogeographic signal suggested by the molecular data and the limited availability of specimens from beyond the Republic of South Africa. We therefore identify our specimens simply as Gandanameno sp. We encourage additional investigations that might further elucidate the systematics of Gandanameno.
Associated with crevices in or under rocks or tree bark in savanna, parks, and gardens. They build a silken tube with a widened entrance; the tube of an adult female under bark can be up to 1 m long (Martin Forman, personal observation). Also found under tree bark well above the ground in dense aggregations (Nikolaj Scharff, Jeremy Miller, Iringa, Tanzania). Prey remnants are placed at the bottom of the tube. Clutches consist of tens of juveniles (Martin Forman, personal observation). Juveniles do not feed on their mother’s corpse and adult females can produce a number of sequential clutches. Males mature in less than one year, females take longer (Martin Forman, personal observation).
- Miller, J; Griswold, C; Scharff, N; Řezáč, M; Szűts, T; Marhabaie, M; 2012: The velvet spiders: an atlas of the Eresidae (Arachnida, Araneae) ZooKeys, 195: 1-144. doi
- Lehtinen P (1967) Classification of the cribellate spiders and some allied families. Annales Zoologici Fennici 4: 199-468.
- Tucker R (1920) Contributions to the South African Arachnid Fauna. II. On some new South African spiders of the families Barychelidae, Dipluridae, Eresidae, Zodariidae, Heracliidae, Urocteidae, Clubionidae. Annals of the South African Museum 17: 439-488.
- Miller J, Carmichael A, Ramírez M, Spagna J, Haddad C, Řezáč M, Johannesen J, Král J, Wang X, Griswold C (2010a) Phylogeny of entelegyne spiders: Affinities of the family Penestomidae (NEW RANK), generic phylogeny of Eresidae, and asymmetric rates of change in spinning organ evolution (Araneae, Araneoidea, Entelegynae). Molecular Phylogenetics and Evolution 55: 786-804. doi: 10.1016/j.ympev.2010.02.021