Spatiator martensi, Wunderlich, Jörg, 2006

Wunderlich, Jörg, 2006, Spatiator martensi n. sp., a second species of the extinct spider family Spatiatoridae in Eocene Baltic amber (Araneae), Zootaxa 1325, pp. 313-318 : 314-317

Spatiator martensi n. sp.

Figs 1–3 , 5

Type material: Male holotype in Baltic amber, its origin is most probably the region of Kaliningrad (Königsberg), F1688/BB/AR/ CJW, SMF.

Derivatio nominis: This species is dedicated to Prof. Jochen Martens, University of Mainz, who discovered numerous arachnids which were new to science; I had the pleasure to describe some of the spiders which were collected by J. Martens in Nepal. J. Martens and the present author have been in close and best contact for 35 years.

Diagnosis (♂; Ψ unknown): Close to Spatiator praeceps , but embolus in S. martensi n. sp. not that slender, forming a large triangle, and tips of embolus and conductor separated ( Fig. 3 ).

Description (♂): Measurements (in mm): Body length 4.3, prosomal length 2.1, opisthosoma: Length 1.9, width 1.3; leg I: Femur 1.3, patella 1.7, tibia 1.15, metatarsus 0.85, tarsus 0.8, tibia IV 1.5, its diameter 0.14.

Color: Body and legs dark brown, opisthosoma yellow brown.

Prosoma ( Figs 1 , 5 ) ca. 1.7 times longer than wide, cephalic part distinctly raised, thoracic fissure long, setae indistinct, mostly short, cuticula fairly rugose. 8 eyes in two rows, anterior median eyes distinctly largest, posterior row distinctly procurved. Basal cheliceral articles large, retrolaterally with a large field of stridulatory files, fangs short, peg teeth hidden. Gnathocoxae converging above the labium which is long and slender. Sternum finely rugose, prolongated between the coxae IV. Petiolus is long and apparently symmetrically bi­partite.

Legs fairly long and slender, order IV/I/II/III, bristles absent, setae short and indistinct­ Tibia and metatarsus I slightly bent, bearing some prodorsal to prolateral spatulate setae, tarsi I–II bear a weak ventral pseudoscopula, metatarsus III bears a dense field of long ventral preening setae in the distal half.

Opisthosoma ( Figs 1 , 5 ) oval, 1.45 times longer than wide, dorsally covered with short setae and hardened (apparently leathery) along its whole length. Epigaster sclerotized, lung covers hairless, small; epiandrous gland spigots absent. Spinnerets short and partly hidden.

Pedipalpus ( Figs 2–3 ) fairly small, with stout articles, tibia with a short prodorsal bristle and at least one dorsal trichobothrium. Cymbium wide, enclosing the bulbus, with few strong prodorsal setae besides long normal setae, bulbus long, tegulum large, embolus in a retroventral position, conductor distinctly separate from the embolus and in a more prolateral position and bent distally to the embolus, sperm duct easily recognizable.

Female: unknown.

Relationships: Only a single congeneric species has been described previously: Spatiator praeceps . The holotype of S. praeceps is a female. I described a male which I regarded as conspecific with the holotype, see Wunderlich (2004: 768, 807, fig. 56) (in this figure I probably mistook the embolus for the conductor). This male is probably conspecific with the female holotype of S. praeceps but — according to the distinctly different structures of their bulbi — it is not conspecific with S. martensi n. sp. No somatic differences are known to exist between these three specimens. This case reflects a fundamental problem in the taxonomy of numerous congeneric — fossil species: (a) the generotype is known from one sex only (or is juvenile), (b) no somatic differences between different species are known and (c) it is not likely to find both sexes in the same piece of amber: How do deal with different congeneric species of the other sex? Occasionally — for practical reasons — fossil specimens from the other sex were described as different species (in contrast to extant species), e.g. by Petrunkevitch (1942). So it would be consequent to designate a new name for Spatiator praeceps sensu Wunderlich (2004) but this is not a matter of this paper. I found no somatic differences between the present holotype and the material of praeceps sensu Wunderlich (2004) but the bulbus structures are clearly different (and in my opinion surely not caused by circumstances of the preservation): embolus and conductor are in close contact in the male of S. praeceps ( Fig. 4 ) in contrast to S. martensi n. sp. ( Fig. 3 ).

Distribution: Early Tertiary (Eocene) Baltic amber forest.

Preservation: The spider is situated at the corner of a yellow piece of amber which has a size of 3.1 x 2.0 x 0.9 mm. Legs and pedipalpi are completely and well preserved, some parts are darkened apparently by heating, the ventral side is weakly covered with a white emulsion, the opisthosoma has a low longitudinal depression dorsally (probably the result of a blow), a bubble is situated close to the left cymbium, but distinctly separated from the cymbial cuticula.

Syninclusions: Four Formicidae , workers (body length 1.3, 2.4, 2.4 and 4.3 mm), remains of the abdomen of an ant (two parts, 1.4 mm long) 2 mm right of the spider in the same layer of the amber, an adult Acari (body length 1 mm), few tiny to small larvae of Acari (body length up to 0.5 mm), numerous stellate hairs of plants, numerous small bubbles and bubble­shaped particles which are dried out as well as particles of detritus.

Notes: (a) Myrmecophagy: Remains of an ant — two parts of an abdomen — near the spider's body may be remains of the spider's prey, but this presumption is quite tentative: Most relatives of the Spatiatoridae , e. g. Archaeidae and Palpimanidae , are araneophages. The complete ants in the same piece of amber are apparently not injured.

(b) Myrmecomorphy: The silvery glancing cuticle in most congeneric specimens ( S. praeceps ) which are preserved in pieces of amber which were not heated, the slender body and legs as well as the raised cephalic part — which give the illusion of a tripartite body of the spider — may be hints that these spiders were only weakly ant­shaped. We do not know the behavior of the fossil spiders, and a saddle­shaped inclination of the opisthosoma is absent. Therefore I am not sure about the actual ant­mimicry of these fossil spiders. The largest ant which is embedded together with the spider has the same body size as the spider and may have been a model of a probable Batesian mimicry. The small ants may have been the model of conspecific juveniles.

Figures

FIGURE 5. Spatiator martensi n. sp. (Spatiatoridae), fossil ♂ in Baltic amber, dorsal aspect. Body length 4.3 mm.

FIGURES 1 – 4. 1 – 3 Spatiator martensi n. sp., ♂ holotype in Baltic amber; 1 outline of the body, lateral aspect. Reconstruction from dorsal and oblique aspects. Only a single eye is drawn; 2 – 3 right pedipalpus, dorsal and ventral aspect. Normal (thin) setae are not drawn. 4 Spatiator praeceps Petrunkevitch 1942, ♂, in Baltic amber, ventral aspect of the right pedipalpus. C = conductor, E = embolus, M = emulsion, S = sperm duct. Scales: 1, 1.0 mm; 2 – 4, 0.2 mm.