Maratus boranup, Otto & Hill, 2018

Otto, Jürgen C. & Hill, David E., 2018, Two new peacock spiders from Western Australia (Araneae: Salticidae: Euophryini: Maratus Karsch 1878), Peckhamia 160 (1), pp. 1-42 : 2-22

Maratus boranup , new species

Type specimens. The holotype male (♂ #1) five paratype males (♂ #2-6), and six paratype females (♀ #1- 6) were collected as immatures at Boranup , Western Australia (34.076983°S, 115.015567°E, 1-14 OCT 2017, coll. J. Otto and D. Knowles), and subsequently reared to maturity . All types will be deposited in the Western Australian Museum , Perth .

Etymology. The species group name ( boranup , noun in apposition) refers to the Boranup area, just south of the town of Margaret River in southwest Western Australia, where this species was found. Boranup is an Aboriginal (Noongar) word that means place of the male dingo.

Diagnosis. Genitalia of this species closely resemble those of M. flavus (see below), but also a number of other Maratus species including members of the mungaich group of Western Australia that may also have a single serration on the ventral margin of the larger outer apex of the embolus of the male pedipalp. Like M. flavus , the pattern of scales covering the dorsal plate of the male opisthosoma (fan) includes a border of relatively large pigmented scales radiating from a series of black lines, something not found in other Maratus that have been described. Based on this unique character we place both species in a new clade within Maratus , the flavus group. The courtship display of the two species is also similar in its reliance on bilateral movement or waving of the outstretched legs III. The two species can be readily separated by the pattern of scales on the fan of the male ( Figure 2 ). The females are very similar, but the female M. flavus has narrower red-brown stripes behind the AME, more like the stripes on the carapace of the male of that species.

Description of male ( Figures 3 -6). The male types are 3.5-3.7 mm in length (n=6). In living males the chelicerae and carapace are black. The chelicerae are mostly glabrous. Long grey setae extend anteromedially from the clypeus. Grey setae surround the front eyes and extend to the rear to cover almost half of the eye region. Dark red-brown setae cover the posterior half of the eye region and surround the lateral eyes on each side. Behind this and on the sides the carapace is mostly black and glabrous, except for a short middorsal stripe of off-white setae, and a marginal band of bright white setae on either side. The PME are closer to the PLE than to the ALE.

The opisthosoma is rectangular/ovoid with a dorsal plate or scute covered with a distinctive pattern of scales. The iridescent background scale cover of this plate appears grey to light pink or lilac. On this background larger, pigmented orange scales radiate from a series of black lines or figures, and there are four bars of pigmented orange scales along the rear margin ( Figures 2 :2; 3:4). Each lateral margin of the fan bears a small orange flap toward the front, and a tuft of long, white setae surrounded by orange scales on either side toward the rear ( Figures 2 :1; 3:7,13). Although the opisthosoma is partly elevated by a mating male, we have not seen it displayed during courtship or agonistic encounters, and the small flaps are not extended. Off-white setae are present on either side of the opisthosoma below the dorsal plate, but these are sparse ventrally. Behind the dorsal plate the opisthosoma is black. Above the anal tubercle is a small triangular patch of white setae, and the spinnerets are black. The underside of the opisthosoma is brown with somewhat irregular darker areas. A more-or-less distinct black line may be present on either side of the venter. From below, the proximal part of each leg (coxa to proximal half of the femur) is brown and covered with scattered off-white setae. The sternum, labium, and endites are brown to dark brown and mostly glabrous.

Legs I and II are shorter, legs III and IV longer, and legs III the longest. Distal segments of legs I, II and IV are irregularly banded with alternating light brown to black based on the distribution and colouration of setae. Legs III, which play a major role in the display of these spiders, are mostly black from the femur to the metatarsus, and the tarsus is covered with bright white setae that extend over the grey footpads. The dorsal side of each femur III is covered with brown to off-white setae. There is a small patch of white setae to the front and rear of each distal tibia III ( Figure 3 :17,18,21), and these patches, although small, are clearly visible toward the front during courtship display. The pedipalps are similar to those of many other Maratus , with a heavy black outer apex in front of a shorter black inner apex of the embolus (Figure 6). In some specimens a single serration or irregular projection can be observed along the ventral edge, proximal to the tip, of the outer apex when viewed from the side. Above, the pedipalps are covered with off-white or light brown setae. Below, they are dark brown.

Description of female ( Figures 7-10 ). The female types are 4.6-5.0 mm in length (n=6). The chelicerae are brown, translucent, and glabrous. The carapace is light brown except for the dark brown dorsum. Longer off-white setae extend anteromedially from the clypeus, and off-white setae surround the lower part of the anterior eyes. The eye region is covered with red-brown setae except for a median stripe of light brown or off-white setae that extends behind the PLE to the rear, ending just beyond the point where the carapace slopes steeply to the rear. The sides of the carapace are mostly glabrous except for a lateral stripe comprised of off-white scales that extends to the rear from just in front of each PLE to the rear of each PLE, and scattered dorso-ventrally aligned scales below this. There is no well-defined marginal band. The PME are closer to the PLE than to the AME.

The dorsum of the opisthosoma is dark brown to red-brown with scattered off-white setae, bordered laterally by irregular black straight to wavy, or broken, lines. There are four more-or-less distinct chevrons situated posteriorly along the midline. The sides and venter of the opisthosoma are covered with off-white setae, more scattered with mottling or darker black spots, and an indistinct pair of dark lateral lines, on the venter. A small white triangle of colular setae is present above the black spinnerets.

From below the coxae, trochanters, proximal femora, sternum, and endites are mostly light brown, translucent, and glabrous, except for scattered off-white setae to the rear of the sternum. Legs I and II are shorter and of similar length, and legs III and IV are longer, also of similar length. The legs are generally brown with indistinct bands of either dark pigment or lighter off-white setae. The pedipalps are light brown and translucent with a cover of off-white setae.

As in many other Maratus species, the epigynum has a pair of relatively large ovate to circular fossae, separated by a septum of variable width. Behind each fossa is a larger, ovate to circular posterior spermatheca. Sclerotized ducts are present anterior to each spermatheca, visible through the fossa.

boranup in ethanol.

Immatures ( Figures 11-12 ). Immatures of both sexes resemble the adult female in colouration. By the time that they reach the penultimate stage females look very much like adults, but males have bolder or more contrasting light and dark brown patterns on the opisthosoma.

Courtship display ( Figures 13-16 ). Males do not raise their opisthosoma during courtship display, but they rapidly (~8-13.5 cycles/s) bob it up and down in a nearly horizontal position. In one display ( Figure 14 ) they hold their extended legs III in a variably elevated, bilaterally symmetric V-shaped position, and wave this pair of legs up and down (bilaterally symmetric movement; both legs up then both legs down) at a similar rate (~11 cycles/s). In a second display ( Figure 16 ) they tend to hold both legs III in position as they bob the opisthosoma, but intermittently rotate both extended legs III in the same direction. This movement may be accompanied by slight movement of the body in the same direction. We have also observed a tendency of these spiders to slowly slide the trailing legs I and II along the underlying surface in the direction that legs III are slowly rotated, while continuing to bob the opisthosoma at a rate of ~10 cycles/s ( Figure 16 :8). Males generally hold their pedipalps in front of their chelicerae as they court. The elaborate decoration of the lateral margins of the opisthosoma of these males is somewhat of a mystery as these males were not observed to display the fan either during courtship or during male-male (agonistic) encounters, and they only partly elevated the opisthosoma as they mated ( Figure 17 ). These are not the only Maratus that have elaborate decorations not used in display. For example, male M. harrisi Otto & Hill 2011 from southeastern Australia extend and display with their legs III during courtship, but a close relative from the west, M. lobatus Otto & Hill 2016 , does not ( Otto & Hill 2011, 2016, 2017b). Many members of the Maratus pavonis group, as well as M. tesselatus Otto & Hill 2016 , also retain some decorative scales on the fan but do not use this fan in courtship ( Otto & Hill 2016, 2017b). These examples suggest that either the trade-off between male survival and sexual selection, or even the genetic drift associated with sexual selection, can drive the loss of even highly evolved components of the courtship display of these spiders.

Mating ( Figure 17 ). Male Maratus boranup elevate their opisthosoma at an angle of ~40° as they mate. Habitat. Maratus boranup was found along a roadside in the vicinity of Conto's Campsite at Boranup in Western Australia ( Figure 18 ). Vegetation along this track was dominated by peppermint ( Agonis flexuosa ), jarrah ( Eucalyptus marginata ), marri ( Corymbia calophylla ) and grass trees ( Xanthorrhoea sp. ).

Figures

Figure 2. Comparison of the fan of the male Maratus boranup (1-2) with that of M. flavus (3). In both species relatively large pigmented scales (orange in M. boranup, mustard-yellow in M. flavus) radiate from a series of black lines. M. boranup has a small orange anterior lateral flap and a tuft of long, white setae on either side of the fan, but the fan is only known to be elevated as shown here (1) when the spider mates. In contrast M. flavus will raise the fan as part of courtship display (3), but there are no flaps or long setae on the sides of this fan.

Figure 3 (continued on next page). Living male types for Maratus boranup. 7, Right side of opisthosoma of mating male showing small orange flap and tuft of long white setae surrounded by orange setae at the base.

Figure 7 (continued on next page). Living female types for Maratus boranup.

Figure 9 (continued from previous page). Female type specimens for Maratus boranup in ethanol.

Figure 10. Ventral view of the epigynum of the six female type specimens for Maratus

Figure 11. Immature male Maratus boranup. 7-12, Penultimate stage of three different male types.

Figure 12. Immature female Maratus boranup. 7-14, Penultimate stage of the six female types.

Figure 13 (continued on next page). Courtship display by male Maratus boranup. 2, Display in front of female with wide separation of legs III. 4-5, Sequential positions by male waving the left leg III unilaterally. 11-14, Note the pair of small, bright white spots at the distal end of each tibia III. The opisthosoma may be bobbed up and down but is not elevated during this display.

Figure 14. Sequential but not consecutive high speed video frames (180 fps) showing bilateral waving of legs III (~11 cycles/s) and rapid bobbing of the opisthosoma (~13.5 cycles/s) during courtship display of a male Maratus boranup. Arrows indicate movement of legs III or the opisthosoma relative to the previous frame.

Figure 15. Consecutive frames from a video (25 fps) showing intermittent bobbing of the opisthosoma (~8 cycles/s when active) as legs III were held in a wide position during the courtship display of a male Maratus boranup. Movements of the opisthosoma (arrows) are barely visible from the front.

Figure 16. Eight video sequences (1-8, 25fps) showing movement of legs III by a courting male Maratus boranup. Arrows indicate movement relative to the previous frame in each sequence. 1-3, Three sequences showing sudden rotation of both extended legs III toward the left of the spider. 4, Rotation of both legs toward the left of the spider with slight movement of the body in the same direction. 5-6, Two sequences showing sudden rotation to the right of the spider of both legs III (5.2, 6.2), followed by very slight adjustments of the leg III position (5.3, 6.3). 7, Sequence showing slight adjustments of relative leg III position (7.2, 7.5) as both legs III were rotated to the right (7.3, 7.4), with slight movement of the body in the same direction (cyan arrows). 8, In this sequence the spider moved both legs III slightly to the left while bobbing the opisthosoma up and down at a rate of ~10 cycles/s. The right legs I and II also slid slowly over the surface during this movement (blue arrows).

Figure 17. Mating by Maratus boranup. 1-3, Aerial mating while suspended from the dragline of the female. This pair continued to mate after falling from the branch on which they began to mate. 4, Decorative setae were exposed as the male raised his opisthosoma by ~40° while mating.

Figure 18. Roadside habitat of Maratus boranup at Boranup.