Maratus electricus, Otto & Hill, 2017

Otto, Jürgen C. & Hill, David E., 2017, Five new peacock spiders from Western Australia (Araneae: Salticidae: Euophryini: Maratus Karsch 1878), Peckhamia 152 (1), pp. 1-97 : 26-48

Maratus electricus , new species

Type specimens. The holotype male (♂ #4), 2 paratype males (♂ #6-7), and 4 paratype females (♀ #1-3, 5) were collected at Lake Muir (34.4506°S, 116.6837667°E, 6 OCT 2016, coll. J. Otto and D. Knowles). All females as well as the holotype male (♂ #4) were collected as penultimates and reared to adulthood . All types will be deposited in the Western Australian Museum , Perth .

Etymology. The species group name ( electricus, Latinate form derived from the English word electric, m., adjective) refers to the presence of red parallel lines on the fan of the male that resemble electrical connections on an electronic circuit board.

Diagnosis. Maratus electricus is similar to M. linnaei Waldock 2008 and both species are placed in a new clade, the linnaei group. Males of the two species can be easily identified by the distinctive decoration of their dorsal opisthosoma or fan ( Figure 30 ).

Description of male ( Figures 31 -35). Males were 4.1-4.9 mm in length (n=3).

The carapace including clypeus is black. The clypeus is mostly glabrous except for long white setae near the midline. The chelicerae are also black and glabrous at the base but bear long white setae that extend as far as the base of the fang. The dorsum of the pedipalps is covered with long, bright white setae, and bright white setae also form a distinctive vertical band between the AME and ALE on either side. Shorter grey setae are present between the AME and these also account for the grey background colour of the eye region. A band of dark red to red-orange scales extends to the rear behind each anterior eye, and three narrower bands of the same colour extend between these to the rear of the eye region. A patch of grey scales extends to the front and rear of each PLE. The sides and rear of the carapace are mostly black and glabrous, but there is a narrow medial tract of white scales behind the eye region that extends half-way to the rear margin of the carapace. There is a band of white setae on each lateral margin of the carapace, but this does not extend anteriorly beyond the PME. The PME are closer to the PLE than to the ALE.

The dorsal opisthosoma ( Figure 30 :5-8, Figure 32 :8-9) is nearly cylindrical and has no flaps, with a background comprised of densely packed iridescent light blue scales. Against this background is a distinctive pattern of mostly parallel lines comprised of red-orange pigmented scales. The anterior margin is marked by two prominent tufts of brown to red-orange setae. Toward the rear is a black to dark red transverse band that may bear several small spots of bright iridescent blue scales ( Figure 30 :6-8, Figure 32 :8-9, Figure 33:1,8), and along each posterolateral margin there is a crescent of similar bright iridescent blue scales ( Figure 31 :6-7, Figure 32 :9). Under the microscope these scales are intense blue in certain directions relative to illumination (Figure 33:5-6). These suggest a close relationship with M. linnaei which also has these bright scales along the posterior margin of the fan ( Figure 30 :1-4, Figure 67 ). Extending beyond the posterior margin of the fan on either side are long orange-brown and black setae ( Figure 32 :1) that become more prominent during display ( Figure 31 :5, Figure 32 :6). Above the colulus is a triangle of white setae, and below this the spinnerets are black.

Legs I and II are shortest, legs III and IV longer, and legs III by far the longest. All legs are dark and covered with white setae. The patella, tibia and tarsus of each leg III is decorated with many long, white setae that figure prominently in courtship display. The pedipalp (Figure 35) resembles that of other Maratus with a longer outer and shorter inner apex of the embolus.

Description of female ( Figures 36-41 ). Females ranged from 4.9-5.8 mm in length (n=4). The clypeus and chelicerae are dark brown. As in the male, the clypeus is mostly glabrous except for long off-white setae projecting forward near the median. Similar setae extend to the distal end of each paturon of the chelicerae. The front eyes are also surrounded by off-white setae. The eye region is covered with red-brown to off-white setae, and a dark brown band may extend across the eye region behind each AME. Behind the eye region the carapace is mostly black and glabrous except for a median tract of off-white setae that extends half-way to the posterior margin. On each side off-white to light brown scales or setae comprise a band extending below the lateral eyes to the rear behind the PLE. Below this band the sides of the carapace are mostly glabrous and translucent, and there are no bands on the lateral margins. The PME are slightly closer to the PLE than to the ALE.

The dorsal opisthosoma is mostly dark brown but this may be interrupted with scale patterns suggestive of those of the adult male ( Figure 36 :5, Figure 37 :1). A small white colular tuft is present. The sides and venter of the opisthosoma are light-brown. The posterior spinnerets are black and the anterior (ventral) spinnerets are brown. The sternum and endites are dark brown. The coxae and trochanters are light brown, glabrous, and translucent. The legs are brown but the proximal half of each femur is lighter in colour, bearing many long off-white setae. The pedipalps are also lighter brown and, like all of the legs, have a cover of off-white setae. Legs I and II are similar in length and shorter and legs III and IV are longer, with legs III the longest. The epigynum ( Figure 41 ) resembles that of other Maratus species, with a pair of large fossae in front of a pair of large posterior spermathecae. Variably sclerotized ducts can be seen through the posterior half of each fossa.

Immatures ( Figures 42-43 ). Penultimate males ( Figure 42 ) have a cover of off-white to white setae on the dorsal opisthosoma interrupted by a distinct pattern of dark lines that suggest the pattern of red-orange scale tracts of the adult male. Sides of the carapace are glabrous and there are no marginal bands. Penultimate females ( Figure 43 ) are darker in colour and resemble adult females. Like adult females, they tend to have variable scale patterns on the dorsal opisthosoma that are suggestive of the adult male pattern but less distinctive.

Courtship display ( Figures 44-53 ). Males can advertise by waving a single leg extended to one side at ~2.5 cycles/s, accompanied by movement of both pedipalps up and down in unison ( Figure 47 ). As in M. cristatus , M. linnaei and M. vespa , females approach males and closely follow the side to side movement of their opisthosoma behind the elevated legs III ( Figures 48-49 ). In one sequence shown here ( Figure 50 ) a male made caliper-like movements of the extended legs III while moving both pedipalps up and down. During display the elevated opisthosoma was moved or vibrated continuously. The opisthosoma may be bobbed in place at a rate of ~6-7 cycles/s ( Figure 51 ), or it may be bobbed continuously as the opisthosoma is rotated from side to side and back again at a rate of ~0.5-1 cycles/s ( Figures 52-53 ). This rotation was observed in the presence of side-stepping ( Figures 48-49 ), or in place without stepping ( Figures 52-53 ). When a male stepped from side to side in front of a female during display, the opisthosoma was turned in the direction of the stepping movement (to the right or left) and bobbed continuously.

the opisthosoma as it was held to one side during the display of a male Maratus electricus .

Mating. Mating positions of Maratus electricus are shown in Figure 54 . Like other Maratus , M. electricus commonly mate on the underside of twigs or other plant structures.

Habitat. Maratus electricus was found on the banks of Lake Muir in Western Australia, among low-lying herbacious plants that covered the sandy soil in slightly elevated areas only meters away from the edge of the lake ( Figure 55 ).

Figures

Figure 30. Comparison of adult male Maratus linnaei (1-4) with M. electricus (5-8). Although individual males vary in details of the scale pattern of the dorsal opisthosoma, the general patterns are quite different. The opisthosoma of M. linnaei also tapers more toward the rear, and that of M. electricus is more cylindrical. M. linnaei has an anterior herringbone pattern of dull red scales. Note the prominent pair of tufts of orange to brown setae at the anterior margin of the opisthosoma of M. electricus.

Figure 31. Two adult male Maratus electricus.

Figure 32. Two adult male Maratus electricus.

Figure 36. Two adult female Maratus electricus. 5, This female had distinct patterns of the opisthosoma resembling those of the male.

Figure 37. Two adult female Maratus electricus.

Figure 38. Four adult female Maratus electricus preserved in alcohol.

Figure 39. Ventral view of two adult female Maratus electricus.

Figure 40. Frontal view of two adult female Maratus electricus preserved in alcohol.

Figure 41. Ventral view of the epigynum of four female Maratus electricus preserved in alcohol. The anterior direction is toward the top of the page.

Figure 42. Penultimate male Maratus electricus.

Figure 43. Four penultimate female Maratus electricus.

Figure 44. Courtship positions of a male Maratus electricus. 1-6, Elevated positions. The elevated opisthosoma was bobbed continuously as it was moved from side to side behind the elevated and partly flexed legs III. The bright white pedipalps were held in an extended lateral position, aligned with lines of bright white setae between the AME and ALE. 8, Female studying the display of a male.

Figure 45. Courtship positions of a male Maratus electricus. 5-13, Female in foreground closely following the male.

Figure 46. Courtship positions of two male Maratus electricus.

Figure 47. Sequential video frames (25 FPS) showing a unilateral wave with the extended leg RIII by a male Maratus electricus. Arrows indicate movement of leg RIII and the pedipalps relative to each preceding frame. There were ~2-3 wave cycles/s. Note bilateral raising and lowering of the pedipalps (pedipalp flicker) at a rate of ~6 cycles/s toward the end of this sequence. This appears to represent a form of advertisement to get the attention of females that may be in the area.

Figure 48. Sequential but not consecutive video frames (25 FPS) showing a female closely following the display of a male Maratus electricus at an eye-to-eye distance of only ~4 mm. The opisthosoma was continuously bobbed as it was turned in the direction (alternately to the left or right) of side-stepping by the male.

Figure 49. Sequential video frames (25 FPS) showing a female (foreground) closely following a male Maratus electricus.

Figure 50. Consecutive video frames (25 FPS) showing "caliper" movement of legs III and moderate pedipalp flicker during the display of a male Maratus electricus. Arrows indicate movement relative to the preceding frame in this sequence. Caliper movement is easy to see in the video record but not so obvious in still frames like this.

Figure 51. Consecutive video frames (25 FPS) showing continuous (~6.6 cycles/s) movement or bobbing of

Figure 52. Consecutive video frames (25 FPS) showing rotation of the opisthosoma from the right to left side over 1.16s by a male Maratus electricus in place. Bobbing of the opisthosoma was continuous during this rotation.

Figure 53. Sequential video frames (25 FPS) showing ~3.5 rotations (~0.5/s) of the opisthosoma as it was moved from one side to the other over ~7s by a standing male Maratus electricus. The opisthosoma was bobbed continuously as it was rotated.

Figure 54. Mating positions of M. electricus. 2-6, Mating started in a hanging position beneath a twig that was rotated for better viewing.

Figure 55. Habitat of M. electricus on the banks of Lake Muir, Western Australia. Higher ground in the foreground slopes down to a stand of white-barked Melaleuca trees standing in water at the edge of the lake.

Figure 67. Courtship display by male Maratus linnaei. Legs III were held in a caliper-like position when the male waved and bobbed the opisthosoma near an attentive female.