Maratus tessellatus, Jürgen C. Otto & David E. Hill, 2016

Jürgen C. Otto & David E. Hill, 2016, Seven new peacock spiders from Western Australia and South Australia (Araneae: Salticidae: Euophryini: Maratus), Peckhamia 141 (1), pp. 1-101 : 53-67

Maratus tessellatus , new species

Type specimens. The holotype male (♂ #1), two paratype males (♂ #2-3), and two paratype females (♀ #1-2) were collected at Bunbury, WA (33.36683 °S, 115.62243 °E, 31 AUG 2014, coll. J. Otto and D. Knowles, among vegetation and on coastal sand dunes). Two paratype males (♂ #4-5) and four paratype females (♀ #3-6) were raised from eggs laid by females collected at that location. These will be deposited

in the Western Australian Museum, Perth.

Etymology. The species group name ( tessellatus, Latin , m., adjective, English translation tessellated) refers to the presence of a distinctive tessellated or mosaic pattern on the dorsal opisthosoma of the adult male.

Diagnosis. Male Maratus tessellatus have a variable but distinctive pattern of dark red to brown spots on a background of grey scales on the dorsal opisthosomal plate that cannot be confused with any other Maratus . The male pedipalp and the female epigynum are typical for the genus, however, and cannot be used as a reliable basis for identification. The colouration of females is also similar to other Maratus , but

females have a subtle pattern of lighter scales and light cuticle on the posterodorsal opisthosoma in the shape of four or five stacked chevrons (herringbone), pointing toward the front and decreasing in size toward the rear.

Description of male ( Figures 60-63 ). Males (N=4) ranged from 4.05 to 4.27 mm in length. The clypeus is black, with long white setae projecting anteromedially over the black and glabrous chelicerae. The carapace is black. The eye region is covered with grey setae, interrupted by stripes of dark red-brown setae behind each of the anterior eyes, with a fifth median stripe. These stripes do not completely cross

the eye region toward the front. Behind the eye region the dorsal carapace is mostly black and glabrous, except for dorsolateral patches of grey or dark red-brown scales behind the posterior eye row on either side, and a prominent median thoracic stripe of bright white scales that extends halfway to the posterior margin. The sides of the carapace are also black and mostly glabrous, with scattered white setae mostly toward the front. A well-defined marginal band of bright white scales is present. The PME are much closer to the PLE than to the ALE. The dorsal opisthosoma has a well-defined plate that is decorated with a distinctive but variable pattern of dark red to dark brown spots or patches on a uniform background of grey scales ( Figures 60-61 ). The posterior margin of the plate is divided or indented at the median, and fringed with no flaps. It is not raised or expanded during courtship display. Behind this plate the dorsal opisthosoma is dark brown, lighter at the median where a more-or-less distinct stripe of lighter setae joins the rear of the plate to the colulus, and a small triangular, white colular patch of setae is present above the dark grey or black spinnerets. Curiously, the posterodorsal opisthosoma just behind the plate can appear bright yellow in alcohol ( Figures 62 :2, 63:4), a colour that has no relationship to its colour in life. The sides of the opisthosoma are light brown with a series of indistinct, darker longitudinal lines. Below, the opisthosoma is light brown, with a large dark brown central patch. The coxae, sternum, labium, and endites are mostly glabrous and translucent grey, with scattered setae.

Legs I and II are of similar length, legs III and IV longer, and legs III by far the longest. Legs I, II, and IV are banded with dark rings alternating with rings of off-white setae. The front of each femur III is covered with shorter, light off-white setae. Each tibia and metatarsus III is black, with prominent fringes of black setae on the metatarsus. The tarsus is covered with bright white setae. Above or in front the pedipalps

are covered with long off-white to light brown or tan setae. The pedipalps are typical for Maratus , with two sharply pointed apices of the ebolus ( Figure 63). The outer apex is larger, the inner smaller. The two apices are barely separated in the individuals that we examined.

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Description of female ( Figures 64-68 ). Females (N=2) ranged from 4.91 to 4.92 mm in length.

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The clypeus is light brown and translucent, with long white setae projecting anteromedially over the light brown, translucent, glabrous chelicerae. The pedipalps are light coloured and covered with longer offwhite setae. The eye region is covered with light brown setae, interrupted at the rear by a darker, indistinct stripe behind each AME. These setae surround the eyes, and extend below and behind the PLE

half-way to the rear margin of the carapace. The PME are closer to the PLE than to the ALE. The dorsal carapace, including cuticle of the eye region and two broad bands extending from the eye region to the rear of the carapace, is dark brown ( Figure 68 :2). The sides of the carapace are mostly light brown, glabrous, and translucent, and there is no marginal band. A prominent median thoracic tract of light brown setae, with light cuticle beneath, extends behind the eye region half way to the rear margin. The underlying stripe of light cuticle extends to the rear margin. The opisthosoma is marked with a dark brown dorsum flanked by wide, light brown to off-white marginal bands. At the rear of the dark brown dorsum a lighter, herringbone pattern is present, comprised of four to five chevrons pointed forward, each decreasing in width toward the rear. The underside of the opisthosoma is covered with off-white setae. The coxae, sternum, labium, and endites are glabrous, translucent and grey, except for scattered longer off-white setae emerging from the posterior sternum.

Legs I and II, of similar length, are shorter than legs III and IV. Legs III are longer than legs IV. The legs are light brown to yellow brown and bear scattered off-white setae, interrupted by dark pigment near the joints that give these a ringed appearance. The epigynum ( Figure 68 :11-15) has extensive but variable sclerotization of ducts visible through the posterior part of each fenestra, a septum of variable width

between the fenestrae, and large posterior spermathecae of variable diameter.

Immatures. Early instars ( Figure 69 :1-4) have a pattern of setae and pigmentation that resembles that of the adult female, with a distinct herringbone pattern on the posterodorsal opisthosoma. Penultimate females ( Figure 69 :5-12) are close to adult females in appearance. Penultimate males ( Figure 69 :13-19) resemble the females, but have bulbous, developing pedipalps, an entirely dark brown to black carapace,

narrow marginal bands of off-white scales, and darker but indistinct transverse bands on the dorsal opisthosoma that suggest some features of the pattern seen in the adult male.

Courtship and mating. Display by a male facing a female ( Figures 70-72 ) is relatively simple in Maratus tessellatus and does not involve the elevation or display of the opisthosoma. During this display the male faces the female with legs III extended and elevated to either a near-vertical position, or to a lower (Vshaped configuration) position. From this position, the legs III may be symmetrically lowered and then

raised again almost continuously, or at intervals ranging from 0.1- 1.0s. High speed (1000fps, Figure 68 ) analysis of this motion reveals that the legs are vibrated at a very high rate of ~30 cycles/s when they are moved, each cycle consisting of lowering of the legs followed by return to their original position. As observed in other Maratus , males lower their extended legs III and touch the carapace of the female with legs I during their final approach ( Figure 73 ). Also as in other Maratus , the female can rotate her opisthosoma by 180° to facilitate mating ( Figure 74 ).

Display by females. Several sequences of female display to courting males, apparently a sign of rejection by the female observed in many Maratus species, are shown in Figures 75 and 76 . When displaying in this manner, females usually turn away from the courting male and raise their opisthosoma, intermittently rotating it from side to side. They may also extend one or both legs III and wave these. In

one trial with a reared male and female (27 FEB 2016), the virgin female initially displayed rejection in this manner to the male. Minutes later the male followed her to a position beneath a branch and they mated. Since a male does not appear to have the ability to distinguish between a virgin and a mated female, the persistence that males exhibit in response to this display is warranted.

Habitat and distribution. Maratus tessellatus males and females were found as they patrolled irregular, dry branches and stems in vegetation on top of old coastal sand dunes near Bunbury ( Figure 77 , map

Figure 1 ).

Figures

Figure 1. Localities for seven new Maratus species from the southern coast of Western Australia and South Australia. Maratus albus and M. lobatus are widely distributed. M. australis and M. vultus are each known from two localities near the southern coast of Western Australia. Each of the other three species (M. bubo, M. tessellatus, and M. vespa) has been found at a single locality in the southwestern corner of Australia, south of Perth.

Figure 60. Views of three different adult male Maratus tessellatus.

Figure 61. Adult male Maratus tessellatus. 1 - 10, Views of two different males. 10, This male has a distinct off-white, median stripe extending from the rear of the dorsal plate to the colulus. In other males this stripe is present, but not as distinct. 11 - 12, Ventral views.

Figure 62. Four different adult male Maratus tessellatus in alcohol.

Figure 64. Four different female Maratus tessellatus.

Figure 65. Views of a female Maratus tessellatus.

Figure 66. Ventral views of four female Maratus tessellatus.

Figure 67. Three female Maratus tessellatus in alcohol.

Figure 68. Female Maratus tessellatus in alcohol. 1 - 10, Two females. 11 - 15, Epigynum of five different females.

Figure 69. Immature Maratus tessellatus, reared from broods produced by females collected at the type locality. 1 - 4, Early instars already exhibit much of the adult female pattern. 5 - 12, Penultimate females are very similar to the adults. 13 - 19, Penultimate males have a dark carapace with a narrow marginal band and dark transverse stripes on the dorsal opisthosoma.

Figure 70. Positions assumed during the courtship display of three different male Maratus tessellatus.

Figure 71. High speed (1000 fps) analysis of leg III movement during courtship display by a male Maratus tessellatus. Each cycle of left / right leg movement (arrows) takes about 33 msec, for a frequency of about 30 / s. This movement appears only as a blur in 25 fps video recordings (Figure 68).

Figure 72. Consecutive frames from a 25 fps video recording of courtship display by a male Maratus tessellatus. Movement and vibration during this entire 1.56 s interval was almost continuous. In other records there was less movement of legs III accompanied by intermittent vibration (~ 30 / s vibrations at 0.5 - 1.0 s intervals with legs III in a near vertical position).

Figure 73. Final approaches of two different male Maratus tessellatus to a courted female.

Figure 74. Mating by a Maratus tessellatus pair.

Figure 75. Three views of the elevated position of a female Maratus tessellatus during a rejection display.

Figure 76. Selected frames from three 25 fps video recordings of rejection display by female Maratus tessellatus. 1 - 6, Arrows indicate slow waving of the extended leg LIII. 7 - 12, Arrows indicate movement of the opisthosoma as it was waggled. 13 - 24, Arrows indicate both waggling of the opisthosoma and waving of the extended leg LIII.

Figure 77. Maratus tessellatus male (2) and female (3) in their habitat in vegetation on top of old coastal sand dunes (1).