Araneus bonali Morano

Morano, Eduardo & Bonal, Raul, 2018, Araneusbonali sp. n., a novel lichen-patterned species found on oak trunks (Araneae, Araneidae), ZooKeys 779, pp. 119-145 : 123-129

Araneus bonali Morano sp. n. Figures 1, 2, 3, 4, 5

Material.

Holotype. Female holotype collected by E. Morano in Spain (Map 1): Huecas (Toledo), 581 metres above sea level (lat. 39.994°long. -4.216°). 27 Sep 2013 (collected by branch beating) (voucher number MNCN 20.02/17497, National Museum of Natural Sciences (CSIC), Madrid, Spain).

Paratypes. Collected in the same locality than the holotype but on different dates, the following 4 males & 3 females. Coordinates and voucher numbers are shown: 1♂, 25 Sep 2012 (trunk traps), 570 m.a.s.l. (lat. 40.013°long. -4.213°) (MNCN 20.02/17499); 1♀, 15 Oct 2012 (beating), 548 m.a.s.l. (lat. 39.994°long. -4.216°) (MNCN 20.02/17504); 1♂, 22 Oct 2012 (trunk traps), 548 m.a.s.l. (lat. 39.994°long. -4.216°) (MNCN 20.02/17500); 1♂, 30 Oct 2012 (trunk traps), 548 m.a.s.l. (lat. 39.994°long. -4.216°) (MNCN 20.02/17501); 1♀, 31 Oct 2012 (trunk traps), 564 m.a.s.l. (lat. 40.013°long. -4.213°) (MNCN 20.02/17502); 1♂, 20 Aug 2013 (beating), 570 m.a.s.l. (lat. 40.013°long. -4.213°) (MNCN 20.02/17498); 1♀, 27 Sep 2013 (trunk traps), 570 m.a.s.l. (lat. 40.013°long. -4.213°) (MNCN 20.02/17503). All these individuals were deposited in the collection of the National Museum of Natural Sciences (CSIC), Madrid, Spain (MNCN).

Additional specimens studied

(Map 1). Spain. Ciudad Real: Piedrabuena, Bullaque river, "Tabla de la Yedra", 551 m.a.s.l., (lat. 39.041°long. -4.230°), 07 August 97, 1♂ (beating) E. Morano leg (EMH-0899); Isla de Algeciras, P.N. Las Tablas de Daimiel, 617 m.a.s.l, (lat. 39.167°long. -3.661°), 15 July 2015, 2 imm (beating) & 15 October 2015, 1♀ (beating), E. Morano leg (vials n°1522 & 1936). Cáceres: Dehesa Casablanca, Guijo de Granadilla, 405 m.a.s.l. (lat. 40.077°long. -6.097°), 02 November 2016, 1♀, (beating) Morano et al. leg (vial n°1489). Collected by E. Morano in the same year (2013) and locality (Huecas) than the holotype and paratypes but on different months the following specimens have been studied and deposited in the personal collection of Eduardo Morano: February, 1 imm (beating), (lat. 40.013°long. -4.213°); May, 1 imm (beating) (lat. 39.994°long. -4.216°); June, 7 imm (beating) (lat. 39.994°long. -4.216°) & 8 imm (beating) (lat. 40.013°long. -4.213°); July, 17 imm (beating) (lat. 39.994°long. -4.216°) & 7 imm (beating) (lat. 40.013°long. -4.213°); August, 1 imm (beating) (lat. 39.994°long. -4.216°) & 1 imm (beating) (lat. 40.013°long. -4.213°); September, 1 ♀ (beating) (lat. 39.994°long. -4.216°) & 1 ♀, 2♂ (trunk traps) (lat. 40.013°long. -4.213°); October, 1 ♂, 1 imm (beating) & 1♀, 1♂ (trunk traps) (lat. 39.994°long. -4.216°).

Etymology.

The specific name is dedicated to Dr. Raul Bonal.

Diagnosis.

Within the European fauna Araneus bonali sp. n. resembles Gibbaranea gibbosa (Walckenaer, 1802) due to its colouration (Figure 3) but does not have its characteristic humps on the opisthosoma. The design and greenish coloration of the opisthosoma and the lack of modifications in the male tibias II differentiates the new species from the small sized, and also usually collected in tree canopies, A. sturmi (Hahn, 1831) and A. triguttatus (Fabricius, 1775). The structure and morphology of the median apophysis of the male palp and the scape and basal plate of the female epigyne of Araneus bonali distinguishes it from any similar Araneus species.

Description.

Female (holotype). Measurements of the holotype are shown (ranges for paratypes in parentheses). Total length: 6.0 (5.1-7.2); Prosoma length: 2.4 (2.0-2.5); Prosoma width: 2.5 (1.8-2.5); Opisthosoma length: 4.4 (3.6-4.4); Opisthosoma width: 4.0 (3.2-4.1). Eye diameter: AME: 0.125; ALE: 0.10; PME: 0.10; PLE: 0.075. Distance between eyes: AME - AME: 0.150; AME - ALE: 0.325; PME - PME: 0.125; PME - PLE: 0.375; AME - PME: 0.10; ALE - PLE: 0.05; Height from clypeus to AME: 0.05; Height from clypeus to ALE: 0.05.

Carapace covered by white hairs (Figs 3, 4). Greyish green cephalic area, with a pair of black side bands going from the ocular area to the fovea. Clypeus and sides of the cephalic area dark brown. Glabrous and cream-coloured posterior thoracic region, usually covered by the opisthosoma. Eight eyes in two transverse rows, the four ME arranged in a trapezoid widely separated from two LE. AME distance wider than PME, ME protrude frontally and AME slightly larger than PME (which have a narrow tapetum). Chilum absent. Chelicerae with a proximal boss, their base of the same dark colour than the ocular region and the clypeus. Chelicerae with three teeth in their margins, the median tooth smaller in both cases. Greyish green sternum with dark radial and central bands in the ventral side of the prosoma. Wider than longer labium with a distal white margin. Endites swollen, rebordered, and square, with white internal area, their length only slightly larger than their width. Both have the same colour than the sternum.

Short and relatively stout legs. The first pair the longest and the third the shortest; the second slightly longer than the fourth (Table 1). Dark green coxae and trochanters, rest of segments pale green. Brownish apical third of the femur, base dotted. Patellae usually dark brown, the rest of the segments with dark brown rings at the middle and end. Tarsi without trichobothria.

In females, tibia I and II with 3-4 pairs of lateral spines and 5-6 pairs of ventral spines. Metatarsus I and II with 5-6 spines on the inner side and three basal spines on the outer side. However, the spines are an extremely variable character because they can be lost and may appear in unusual positions or vary with the dimensions of the segments ( Grasshoff 1968; Berman and Levi 1971; Carmichael 1973).

Triangular opisthosoma slightly longer than wide, with brown setae. Folium with a black band and a narrow white line that marks the limit between the anterior spots, the posterior humps, and the greenish folium sides. Three pairs of sigillae, the two anterior ones larger. In females, two pairs of anterior humps, much smaller in males. General colouration mimetic with lichens and mosses, difficult to tell the spiders apart when on the oak branches and trunks. White ventral background with two dark lateral spots; two book lungs and an inconspicuous spiracle before the colulus, behind the colulus six spinnerets.

Female genitalia. The scape of the epigyne short and wrinkled (Fig. 2A, B), with setae directed backwards on the surface. Straight scape ending in a spoon-shaped tip and attached to the basal epigynal plate by lateral sclerites. The basal plate or posterior piece as long as the epigyne, with a light tonality and rectangular-shaped, without paired basal lamellae. Ventral genital openings continued internally with the copulatory ducts that connect with the small elliptic spermathecae (Figure 2C).

Male (Paratypes). Ranges are shown (and mean values within parentheses) (Table 2). Total length: 3.2-4.3 (3.84); Prosoma length: 1.8-2.3 (2.10); Prosoma width: 1.3-2.1 (1.73); Opisthosoma length: 1.7-2.8 (2.28); Opisthosoma width: 1.2-2.0 (1.76). Eye diameter (average): AME: 0.125; ALE: 0.10; PME: 0.10; PLE: 0.075. Distance between eyes: AME - AME: 0.150; AME - ALE: 0.250; PME - PME: 0.125; PME - PLE: 0.325; AME - PME: 0.10; ALE - PLE: 0.05; Height from clypeus to AME: 0.05; Height from clypeus to ALE: 0.05.

Male general appearance and colouration similar to females (Figure 5) but, according with the large sexual size dimorphism typical of araneids (Hormiga et al. 2000), males are 1.5 times smaller; males slender than females and with a smaller triangular opisthosoma. Light greenish humps, delimited by white lines that continue into the posterior folium. One tooth on the side of the endites. Leg colour identical between sexes, but not their morphology. In males, coxa I has an apical curved hook distally that fits in into the corresponding groove of femur II during copulation. Tibias II curved and armed with four pairs of lateral spines. Metatarsus II with strong spines.

Male genitalia (Figure 1). Palpus with two dorsal macrosetae (on the patella and on the tibia), palpal femur with a small ventral tubercle. Compact genital bulb attached at the base of the cymbium, reduced paracymbium with the standard araneid shape (hook or knob); tegulum covering the base of the palpus. Median apophysis comparatively short on the right side of the radix, with a spur and three distal teeth easy to observe in mesal view (Figure 1B). In this view, the stipe margin is serrated in the area close to the median apophysis. Embolus short, stout and curved towards the conductor and partially covered by the terminal apophysis. Conductor with a swollen distal margin and a large terminal apophysis ending in a fine and blunt tip. The expanded bulb (Figure 1C) shows the presence of radix, stipes, distal haematodocha, and subterminal apophysis.

Phylogenetic analyses.

The blast of the nuclear 28SrRNA sequence of the new species recovered Araneus angulatus and Araneus diadematus as the most closely related species (sequence similarity 99%). The 28S gene tree (Figure 6) showed that, except Araneus dimidiatus (L. Koch, 1871), Araneus spp. formed a nonexclusive clade, albeit with low support (PP = 0.64), that also include species from closely related genera such as Neoscona Simon, 1864 and Larinioides .

The three specimens of the new species analysed yielded the same cox1 haplotype. The lowest uncorrected intraspecific genetic distance was 11.7%, to Araneus alsine (Walckenaer, 1802). The average genetic distance among Araneus species was 14.9%. The node support values of the concatenated tree were low and most relationships were unresolved. A. bonali formed a small clade with A. iviei (Archer, 1951) and A. alsine , but with a very low support (PP = 0.55) (Figure 7). A clade including A. diadematus and eleven additional species, was recovered albeit with low support (PP = 0.82) (Figure 7). The results show that Araneus angulatus and the new species are excluded in the diadematus group.

Habitat distribution and phenology.

Araneus bonali is linked to trees, as not a single individual was collected in ground traps or in grasslands. The distribution patterns differed significantly between juveniles and adults though, as all juveniles (44 individuals) were collected in oak branches whereas most adults (66% of a total of 15 specimens) were captured in trunk traps (Figure 8; Chi = 6.66; df = 1; P <0.01). Phenology also differed between age classes (Chi = 135; df = 3; P <0.001). With the exception of one capture in February, the bulk of juveniles appeared in May and matured throughout spring and summer. Adult presence and reproduction was concentrated in the months of September and October and none were caught in winter (Figure 9).

Araneus bonali was collected in 18 of the 24 holm oaks sampled. The number of juveniles and adults caught at each oak were significantly related (F1, 22 = 31.41; P <0.001). The total number of individuals trapped at each tree was unrelated with canopy surface (GLM Estimate = 0.001; Z = 0.35; P = 0.72) or the pairwise spatial distance between holm oaks (Mantel test R = -0.04; P = 0.62).