Maratus sceletus, Otto & Hill, 2015

Otto, Jürgen C. & Hill, David E., 2015, Two new peacock spiders of the calcitrans group from southern Queensland (Araneae: Salticidae: Euophryinae: Maratus), Peckhamia 121 (1), pp. 1-34 : 16-31

Maratus sceletus , new species

Type specimens. The holotype male (♂ #13) was collected at Wondul Range National Park in southern Queensland (S 28.04862°, E 151.04878°, 13 SEP 2013 M. Girard & E. A. King coll.). Paratypes (♂ #1-12, ♀ #1-4, ♀ #5-6 collected as immatures and raised to maturity) were found nearby (S 28.04841°, E 151.04669°, 438 m, 27, 29 JUL 2014, J. Otto coll.). All types will be deposited in the Queensland Museum in Brisbane .

Etymology. The species group name ( sceletus , noun, Latin) means skeleton, a reference to the bold, skeleton-like appearance of the male spider.

Diagnosis. Male Maratus sceletus resemble other members of the calcitrans group in their general pattern, but have little colouration and are mostly black and white. They also have a distinct tuft of long, white setae extending toward the front between the AME. Legs III are never extended during their fan dance, but are unilaterally elevated in a flexed position.

Description of male ( Figures 18-23 ). Males (N=8) ranged from 3.7 to 4.2 mm in body length, not including the spinnerets.

The carapace and chelicerae are black. The clypeus is solid black, but interrupted by a prominent tuft of long white setae extending to the front between the AME. From the front, the pedipalps are black with a prominent line of bright white setae on their anterior margins. Since the pedipalps are normally rotated to meet at the median, these white setae comprise an uninterrupted horizontal band separating the black clypeus from the black dorsal cymbia. The eye region is black, with connected anterior and lateral bands of bright white setae, and a separate transverse band of white setae across the middle. There is a wider transverse white band behind the PLE, separated into two bands on either side that extend toward the margin of the carapace. There is no marginal band of the carapace, however, and the sides and rear are black.

The opisthosoma is oval in shape but without lateral flaps. The dorsal pattern is unique and skeleton-like, with a pattern of dark red to black scales arranged in four longitudinal bands toward the front, and five larger transverse bands behind these, on a background of iridescent blue scales. This pattern is punctuated by bright white setae comprising an anterior marginal band, a narrow anterior median band, and four tufts of longer white setae on either side. One more tuft of long white setae is present on either side of the spinnerets, which are black with tufts of white distal setae, more visible when these are extended during courtship display. The underside of the opisthosoma and the coxa of legs III and IV are light brown with bright lateral bands of white setae, and otherwise scattered white setae, fading to yellow or white in ethanol. The sternum, coxae of legs I and II, labium, and endites are dark brown in living spiders.

Legs I and II are about the same length, much shorter than legs III and IV. Legs III are by far the longest. All legs are generally black, with dorsal stripes comprised of white setae. Femora and tibia of legs III also bear a ventral fringe of white setae, demarcating an anterior black stripe that is visible from the front when the male displays to a female. The tarsi of legs III are not prominently marked as in most other Maratus , and figure little in display as these legs are only raised and flexed but not extended.

The outer and inner apices of the embolus of the pedipalp are prominent and well-separated. The outer apex is large and blunt, whereas the inner apex is smaller and pointed at the tip.

inset rectangle in (4), showing iridescent light-blue scales at upper left, longer bright white scales at upper right, and narrower black scales elsewhere.

Description of female ( Figures 24-27 ). Paratype females (N=2) ranged from 5.0- 5.3 mm in body length, not including the spinnerets.

colouration, with scattered grey to white setae on the underside of the opisthosoma.

The eye region, including the lateral margins surrounding the lateral eyes, is darkly pigmented but otherwise covered uniformly with grey to white setae. Longer grey to white setae project forward on the clypeus below the AME. Otherwise, the clypeus, chelicerae, and sides of the carapace are light-brown, translucent, and glabrous. The PME are almost equidistant between the ALE and the PLE.

The dorsal opisthosoma bears a distinct pattern of tranverse pigmented areas beneath a uniform covering of grey to white setae. At the median these are somewhat chevron-shaped, terminating in a bold and distinctive 'V' shaped pattern just in front of the spinnerets. Below, the entire body, including the legs, sternum, labium, and endites, is relatively glabrous (except for scattered white to grey setae of the ventral opisthosoma), light-brown, and translucent. Under ethanol, this colour fades to solid white.

Legs I and II are about the same length, much shorter than legs III and IV, and legs III are by far the longest. The legs are mostly translucent, light-brown and glabrous, except for scattered white setae on legs III and IV. Posterior spermathecae of the epigynum are close to the fossae in diameter ( Figure 26 ). Sclerotized ducts barely enter the posterior fossae, and separate medial (bean-shaped) and lateral areas of sclerotization can be seen.

Immatures ( Figure 28 ). Emergent instars have a dark pigmented eye region like that of adult females. Penultimate females resemble adults with respect to the presence of bold markings on the dorsal opisthosoma and white setae on legs III and IV.

Male display ( Figures 29-34 ). Male Maratus sceletus generally approach the female from the opposite side of a stem or blade of grass. If the female is on top, the male approaches from below, in a hanging position. If the female is positioned belly-up beneath a stem, the male approaches from above. The fan dance of the male rapidly alternates from one side of a stem to the opposite side ( Figure 32 ). Positions may be switched 10 times in a 20s interval, with only ~1s or less of display in a single position. The fan is prominently elevated and often waggled from side to side during this display, but the greatest and most rapid movement is that of the extended spinnerets, separately twitched from side to side. During display, the pedipalps are often moved up and down in front of the clypeus and chelicerae. One leg III is elevated but also flexed, displaying a prominent black stripe with little significant movement.

Mating ( Figure 35 ). The final approach and mating of Maratus sceletus is similar to that of other Maratus species that have been observed.

Habitat ( Figure 36 ). Maratus sceletus was found in clumped or bunched grass at Wondul Range National Park. M. jactatus was found nearby, in leaf litter.

Figures

Figure 18. Views of four different male Maratus sceletus. Colours are primarily black and white. In one male (♂ #3, 6-9) bands of the dorsal opisthosoma were dark red rather than black. Note the prominent black stripes on the front of legs III (8). The prominent anteromedian tuft between the AME (3, 4) has not been observed in any other Maratus. As might be expected, up and down movements of the pedipalps play an important role in the display of male M. sceletus.

Figure 19. Views of four additional male Maratus sceletus.

Figure 20. Views of five additional male Maratus sceletus. 7, When the grey posterior opisthosoma and spinnerets (median and posterior pairs) are inflated during display, prominent black proximal and white distal fringes of the spinnerets may be seen clearly. Note the tuft of long white setae at either side of the spinnerets. The inflated portion of the posterior opisthosoma is not as large or prominent as in some other members of the calcitrans group (e.g., M. jactatus), but the spinnerets of M. sceletus are very rapidly, and separately (like fingers) waved during display. 8, Detail of the prominent white median setae that project forward between the AME and from the clypeus, offset by black setae and black cuticle on either side.

Figure 21. Underside of three different male Maratus sceletus. White setae are more prominent on the coxae of legs III and IV. Dark bands separate the white lateral bands of the opisthosoma from the light-brown (or splotched, 2) venter.

Figure 22. Views of male Maratus sceletus in alcohol. 5, Detail of scales from the fan corresponding to the

Figure 23. Views of the left pedipalp of four different male Maratus sceletus. 12, Detailed view of holotype, showing clear separation between the large, blunt outer apex and the smaller, pointed inner apex of the embolus.

Figure 24. Views of four different female Maratus sceletus. Pedipalps, chelicerae, the sides of the carapace, and legs I and II are primarily light-brown, translucent, and glabrous. Cuticle of the eye region and complex dorsal patterns of the opisthosoma are dark. Note the bold V-shaped pattern toward the rear of the opisthosoma (3, 6, 9). Otherwise the white to grey setation is fairly uniform.

Figure 25. Underside of two female Maratus sceletus, showing uniform light-brown, translucent

Figure 26. Rear view of opisthosoma and ventral view of epigyna of four different female Maratus sceletus. 1, Note the prominent V-shaped area of dark pigment toward the rear, and the longer, dark pair of posterior spinnerets surrounding the median spinnerets. 2-6, The posterior spermathecae range in size from slightly smaller to slightly larger than the fossae. Note the narrower bridge between the fossae in (6).

Figure 27. Four different female Maratus sceletus in ethanol. The dark pigmentation of the eye region, lighter orange colour of the posterior carapace, and the dark patterns of the opisthosoma stand out in these specimens. Other areas of the cuticle, normally translucent brown, faded to white in ethanol.

Figure 28. Views of emergent second instar (1-3) and two different penultimate female Maratus sceletus (4-8). The dark eye region and a small pigmented area at the base of the spinnerets (3) can be seen in second instars. Penultimate females closely resemble adults.

Figure 29. Positions assumed during the fan dance of male Maratus sceletus. During this display, one leg III is flexed and raised, but not extended as in most Maratus and as in all other members of the calcitrans group, displaying a prominent anterior black strip running from the femur to the tarsus. With the fan elevated, the extended spinnerets are raised and moved rapidly, and separately, like a set of flailing fingers. 1-2, Up and down movement of the boldly marked pedipalps also plays an important role in this display.

Figure 30. More views of positions assumed during display by male Maratus sceletus. 2, Signalling with a single, flexed and slightly elevated leg III.

Figure 31. Consecutive video frames (1-10, 25fps, exposure/frame 20msec) showing one cycle of up and down movement (~2.5Hz flicker) of the pedipalps of a male Maratus sceletus. Pedipalp movement relative to the preceding frame is indicated with arrows. Movement of the pedipalps is generally synchronous and bilaterally symmetric. They are often raised in more than one step (in this example in two steps shown in frames 2-3 and 6), then rapidly lowered (frame 9). This display may occur in the absence of a female, as shown here, or as a component of the fan dance. As in other salticids, this frequent flicker appears to advertise the presence of the male even when he is stationary.

Figure 32. Sequential but not consecutive video frames (1-10, 25fps, exposure/frame 20msec) showing a male Maratus sceletus displaying first to a female (at lower right in frames 1-6) on top of a narrow grass stem, then moving to display from the other side of the stem. Slight movements of the elevated and flexed right leg III are indicated with arrows (3-5). Display in either position involved very rapid movement of the spinnerets, and sometimes rapid lateral vibration of the elevated fan (frames 4-5). Between each brief episode of display (~0.6s above the stem as shown here), the male crouched low on the stem. Alternation between positions occurs many times throughout the courtship display, with ~1 change of position every 2s (0.5Hz).

Figure 33. Consecutive video frames (1-30, 25fps, exposure/frame 20msec, ~1.16s elapsed time) showing a complete display sequence by a male Maratus sceletus facing a female. Arrows identify lateral movement of the fan during this display. Movement of the spinnerets was far too fast to capture at this frame rate, but contributed greatly to the appearance of rapid movement. The complete cycle of rapid movement (frames 5-26) lasted for about 0.8s.

Figure 34. Consecutive video frames (1-25, 25fps, exposure/frame 20msec, ~0.96s elapsed time) showing part of a display sequence by a male Maratus sceletus facing a female. This male crept over the edge of the leaf on which it is perched to face the female. During this display, the spinnerets were in continuous motion. The elevated and flexed right leg III was not moved appreciably during this sequence, although is some cases (Figure 33) it is moved. Movement of the pedipalps up and down is identified with arrows.

Figure 35. Final approach of a male Maratus sceletus with legs III extended laterally and legs I extended to the front to touch the carapace of a female (1), and mating positions (2-4). As in other Maratus, the female can rotate her opisthosoma by 180°. Note the distinctive 'V' pattern at the rear of the female opisthosoma.

Figure 36. Habitat of Maratus sceletus in grass clumps (3, detail) associated with open woodland at Wondul Range National Park. 4-5, Male M. sceletus climbing on narrow grass stem.