Eriauchenius
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Ordo: Araneae
Familia: Archaeidae
Name
Eriauchenius O. P.-Cambridge, 1881 – Wikispecies link – Pensoft Profile
Type species
E. workmani O. P.-Cambridge, 1881, by original designation.
Diagnosis
Distinguished from the Australian genera by lacking spermathecae in the female genitalia, and instead having a bursa with secretory poreplates and a FSGP, and, in males, lacking the long wiry embolus on the male pedipalps seen in the Australian species. Distinguished from Afrarchaea by lacking the perpendicular keel on the FSGP, and from Madagascarchaea gen. n. by having 2–4 spines on the apex of the cephalon instead of 6, and lacking the retrolateral apophysis on the male pedipalpal patella.
Description
Total length 1.64–6.72. Carapace reddish-to-orangish brown with many white setae on small tubercules, organized in branching rows (see figs 5D, 6B in Wood 2008[3]); pars cephalica elongated forming ‘head’ (distal portion of elongation) and ‘neck’ (constricted portion of elongation), with carapace tilt height divided by carapace length 1.44–2.85, with the angle of carapace tilt 54.7°–88.1°; with a pair of posterior, and often with an anterior pair, of pronounced-to-rudimentary protrusions on apex of cephalon or ‘head,’ each with a small-to-large spine; neck with fissure on anterior side running from chelicerae bases to labrum (see fig. 6B in Wood 2008[3]). AME on a small-to-large bulge with a point or rounded at apex (see fig. 8C in Wood 2008[3]). AME diameter larger than all other eyes; median ocular quadrangle (MOQ) wider in front than behind or than long; lateral eyes contiguous; sometimes with a short spine between median eyes and LE (see figs 8C and 18 in Wood 2008[3]). Sternum reddish-to-orangish brown and longer than wide, hollowed out around coxae, with a border; setae with tuberculate bases; with expanded tubercle on posterior part of sternum, close to 4th coxae (see fig. 9F in Wood 2008[3]), possibly implicated in the abdomen-petiole stridulatory system. Long sclerite between coxae and carapace (see fig. 7C in Wood 2008[3]). Endites converging; serrula strongly pointed; labrum with two lateral projections on dorsal surface (see fig. 6A in Wood 2008[3]). Small round chilum sclerite next to each cheliceral base. One triangular sclerite between and posteriad to the cheliceral bases, and an additional sclerite running along the length of the triangular sclerite base (see fig. 7A in Wood 2008[3]). Chelicerae with a pronounced-to-rudimentary anterior protrusion with a downward or perpendicular pointing long-to-short spine, cheliceral spine/chelicerae length ratio 0.068–0.49; with stridulatory ridges on lateral side, and chelicerae curved to the posterior distal to the stridulatory ridges. The structure used in conjunction with the cheliceral stridulatory file appears to be a group of modified hairs on the prolateral side of the palp (Forster and Platnick 1984[4]; Lotz 2003[5]; Wood 2008[3]); it is unknown whether sclerotized structures on the male palpal bulb are also used in conjunction with the cheliceral file, which has been observed in Madagascarchaea gen. n. (Wood 2008[3]). Peg teeth in three rows; anterior row with two peg teeth and posterior row of two-three, both sitting opposite fang tip, median row of 18–30, strongest distally and gradually grading to normal setae. Teeth on retromargin 2–7, may have different numbers of teeth per chelicera on same individual.
Abdomen rounded in the “bourgini group” (Figs 9–22) or triangular in the “workmani group” (Figs 3–8) due to a single dorsal protuberance, which can be small-to-large; containing numerous small, round, pale indentations throughout and with dark brown to purplish pigment throughout; covered in white-to-brown, thick setae; epigynum and booklung covers flat, sclerotized plates, which are not fused in females, but form a single fused epigastric ventral plate in males; abdominal dorsal plate with ridges (see fig. 5B in Wood 2008[3]), sometimes fused with epigastric plate only in males; dorsal plate sometime extends along the anterior face of the abdomen (scutum) in males only; dorsal plate is always confined to the abdominal petiole region in females. Posterior respiratory system with two spiracular openings (see fig. 5C in Wood 2008[3]).
Spinnerets surrounded by ring; rudimentary-to-fleshy colulus present. The following spinneret description is taken from examining published images of E. workmani (Griswold et al. 2005[6]: figs 21–22): anterior lateral spinneret (ALS) spinning field divided, with one large and one smaller major ampullate gland (MAP) spigot on the median side and with approximately 42 smaller piriform gland (PI) (fewer in male) spigots on the lateral side. Posterior median spinneret (PMS) of female with one large median minor ampullate gland spigot (mAP), one lateral medium-sized aciniform gland (AC) spigot, and two lateral cylindrical gland (CY) spigots; the male PMS is the same except in lacking the CY. Posterior lateral spinnerets (PLS) with a middle row of five AC spigots; in females only, this row is flanked on the anterior side by two CY spigots and on the posterior side by one CY spigot.
Legs reddish or orangish to light brown, often with dark brown bands throughout, but especially on the tibia; covered sparsely with setae; ratio 1-2-4-3 or 1-4-2-3, typically 1-2-4-3 for species found in vegetation and 1-4-2-3 for species found in forest litter; one or two anterior rows of scopulae present on leg I, sometimes also present on leg II, and sometimes with a posterior row as well; metatarsus III and IV with a ventral cluster of modified hairs; femur IV distinctly curved (see fig. 7D in Wood 2008[3]); femur I length 1.48–6.48 times the length of the carapace. Female palp with single claw.
Male pedipalpal femur, patella, tibia and cymbium without apophyses, however a cluster of spine like setae with enlarged bases occurs on the distal retrolateral side of the femur in some “bourgini group” species. Palpal bulb very diverse in shape, forming an enclosed pit that the conductor wraps around in the “workmani group” (Fig. 8D–L) and the “bourgini group – enclosed embolus group” (Fig. 9D–L), and with the embolus exposed and encircled by the conductor in the “bourgini group – exposed embolus group” (Fig. 13D–K). Embolus is heavily sclerotized, unconcealed, and wide-to-thin in the “bourgini group” and is sclerotized only at the tip and recessed in the “workmani group”. Conductor either a small dark ridged spiral that goes around the apex of the bulb and terminates in a triangular point (Fig. 9J–K), or a larger, wider piece that circles around the embolus, often with processes (Fig. 13D–I). In the “workmani group” the MA is present and is hidden behind the embolus in unexpanded bulbs (Fig. 8D–E, H); in most “bourgini group” species the male pedipalpal bulb has only a conductor and embolus, however, in some species a MA is also present (Figs 9E, H, 11D–I, 12D–F, 20D–I); in all “workmani group” species and in some “bourgini group” species there is an additional sclerite (SC) present on the male pedipalpal bulbs that may be an additional process on the conductor instead of a separate sclerite (Figs 8D–E, G–H, 9E–I).
Female genitalic bursa height in “workmani group” greater than bursa width (Fig. 8B), and in “bourgini group” less than or equal to bursa width (Fig. 11B); bursa with secretory poreplates with pores distributed in a small continuous group (Fig. 17C) or in a large discontinuous clumpy group on each side (Fig. 8B), although poreplates are absent in E. bourgini (Millot, 1948) and E. zirafy sp. n. that instead have a sclerotized invagination on either side of the bursa (Fig. 13C); with a dorsal sclerotized plate (FSGP) that can be either a simple arched piece that is wider than long (Fig. 15C) or a more elaborate piece that can have a posterior extension, or points at the top, and that can be longer than wide (Fig. 14B); FSGP in most species with wing-like projections extending to each lateral side that can be reduced-to-large, and that can be heavily sclerotized-to-translucent (Fig. 8B). All species of the “bourgini group” have a large-to-small curved piece that sits posterior to the epigastric furrow, termed the “posterior bar” (Figs 13B, 16B), not present in the “workmani group”. Legendre (1967)[7] suggested that the male palp might come into contact with the FSGP during copulation and that the FSGP may offer tactile information to the male or female. Alternatively, the FSGP may serve as an anchor for muscle attachment (Griswold et al. 2005[6]).
Included species: 6 described species E. bourgini (Millot, 1948), E. fisheri (Lotz, 2003), E. mahariraensis (Lotz, 2003), E. pauliani (Legendre, 1970), E. ratsirarsoni (Lotz, 2003), E. workmani O. Pickard-Cambridge, 1881, and 14 new species described here: E. andriamanelo sp. n., E. andrianampoinimerina sp. n., E. goodmani sp. n., E. harveyi sp. n., E. lukemacaulayi sp. n., E. milajaneae sp. n., E. milloti sp. n., E. rafohy sp. n., E. ranavalona sp. n., E. rangita sp. n., E. rixi sp. n., E. sama sp. n., E. wunderlichi sp. n., E. zirafy sp. n. One species originally described as Archaea, with the extant members later revived as Eriauchenius, has been transferred to Afrarchaea: A. cornutus (Lotz, 2003) (new combination).
Distribution
Madagascar.
Discussion
Eriauchenius contains two main clades, the “workmani group” and the “bourgini group” (Fig. 1). The “workmani group” is distinctive: the abdomen has a single tubercle making it triangular in shape (Fig. 8A), whereas the “bourgini group” has a rounded abdomen (Fig. 9A); the “workmani group” also has a highly elongated, constricted “neck” (Fig. 8A). Furthermore, in the “workmani group” the bursa height is greater than the bursa width (Fig. 8B), whereas in the “bourgini group” the bursa height is less than or equal to the bursa width and there is a posterior bar on the FSGP (Fig. 11B–C). The “workmani group” species are bigger in general than other Madagascan archaeid species, ranging in body length from 3.24–6.72.
The “bourgini group” is further broken up into two groups, the “enclosed embolus group” and the “exposed embolus group.” Unfortunately, specimens from the “enclosed embolus group” were not included in the phylogeny of Wood et al (2015)[8], so it is currently unknown whether this group is monophyletic and what their phylogenetic relationship is to other archaeids. The “embolus enclosed group” contains four species (E. fisheri, E. goodmani sp. n., E. harveyi sp. n., E. sama sp. n.) that share the following traits: the male pedipalpal bulb is enclosed (Figs 9D–L, 10D–F, 11D–K, 12D–F), the female bursa is sclerotized and covered in pores on the ventral side (Figs 9C, 10C, 11C, 12C) as opposed to the anterior or dorsal side in other Eriauchenius, and the AME are virtually flush with the cuticle (Fig. 11L), rather than being on bulges. In the “exposed embolus group” the male pedipalpal bulbs have a more open form, with the embolus exposed and encircled by the elongated conductor, and there is also a membraneous sac on the bulb that is adjacent to the embolus base (Fig. 17D–L). Typical “bourgini group” pedipalpal bulbs have only an embolus and a conductor, and no other sclerites, the exceptions are E. fisheri, E. harveyi sp. n., E. rixi sp. n., and E. wunderlichi sp. n., which also have a MA and SC, and E. goodmani sp. n., which also has a SC.
E. fisheri and E. mahariraensis were transferred to Eriauchenius from Afrarchaea because they lack the FSGP keel observed in Afrarchaea and because the FSGP has a posterior bar. E. mahariraensis was included in the phylogenetic analysis of Wood et al (2015)[8] and fell inside Eriauchenius with a branch support posterior probability value of 1.0. Although, E. fisheri was not including in this phylogenetic analysis, the morphological evidence supports this transfer.
Taxon Treatment
- Wood, H; Scharff, N; 2017: A review of the Madagascan pelican spiders of the genera Eriauchenius O. Pickard-Cambridge, 1881 and Madagascarchaea gen. n. (Araneae, Archaeidae) ZooKeys, (727): 1-96. doi
Images
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![Figure 1. Total evidence phylogeny from Bayesian analysis of molecular and morphological data, from Wood et al. (2015)[8]. Outgroups not shown and with the morphospecies names changed to the new species names from the current study. Posterior probabilities are as follows, greater than or equal to: (*) 0.90; (**) 0.95; (***) 0.99.](/wiki/File:Zookeys-727-001-g001.jpg)
Other References
- ↑ Simon E (1895) Histoire naturelle des Araignées, Vol. I. Roret, Paris, 1084 pp.
- ↑ Wunderlich J (2004) Fossil and extant spiders (Araneae) of the superfamily Eresoidea s.l., with special reference to the Archaeidae and remarks on some higher taxa of the superfamily Araneoidea. Beiträge zur Araneologie 3A: 747–808.
- ↑ 3.00 3.01 3.02 3.03 3.04 3.05 3.06 3.07 3.08 3.09 3.10 3.11 3.12 Wood H (2008) A revision of the assassin spiders of the Eriauchenius gracilicollis group, a clade of spiders endemic to Madagascar (Araneae : Archaeidae). Zoological Journal of the Linnean Society 152: 255–296. https://doi.org/10.1111/j.1096-3642.2007.00359.x
- ↑ Forster R, Platnick N (1984) A review of the archaeid spiders and their relatives, with notes on the limits of the superfamily Palpimanoidea (Arachnida, Araneae). Bulletin of the American Museum of Natural History 178: 1–106.
- ↑ Lotz L (2003) Afrotropical Archaeidae: 2. New species of genera Archaea and Afrarchaea (Arachnida: Araneae). Navorsinge van die Nasionale Museum Bloemfontein 19: 221–240.
- ↑ 6.0 6.1 Griswold C, Ramírez M, Coddington J, Platnick N (2005) Atlas of phylogenetic data for entelegyne spiders (Araneae: Araneomorphae: Entelegynae) with comments on their phylogeny. Proceedings of the California Academy of Sciences 56: 1–324.
- ↑ Legendre R (1967) Un organe épithélial énigmatique annexé aux conduits de fécondation chez les femelles d’Archaeidae (Aranéides). Comptes Rendus de l’Académie des Sciences (Paris) 264: 2314–2316.
- ↑ 8.0 8.1 8.2 Wood H, Gillespie R, Griswold C, Wainwright P (2015) Why is Madagascar special? The extraordinarily slow evolution of pelican spiders (Araneae, Archaeidae). Evolution 69: 462–481. https://doi.org/10.1111/evo.12578
