Maratus trigonus, 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 : 72-96

Maratus trigonus , new species

Type specimens. The holotype male (♂ #13), 10 paratype males (♂ #3-5, 9, 18, 20, 23, 25, 28-29), and 12 paratype females (♀ #10-12, 14-17, 19, 21, 24-25, 34) were collected at Mt. Lindesay (34.83961667°S, 117.3083667°E, 4 OCT 2016, coll. J. Otto). The holotype male (♂ #13), 5 paratype males (♂ #18, 20, 23, 28-29), and 9 paratype females (♀ #12, 14-17, 19, 21, 24-25) were collected as immatures and reared to the adult stage. All types will be deposited in the Western Australian Museum , Perth .

Etymology. The species group name ( trigonus, Latin , m., adjective, English translation triangular) refers to the distinctive triangular shape of the extended fan of the male.

Diagnosis. The pattern of scales on the fan of M. trigonus is unique for this species, including a threepointed "crown" of bright white scales at the posterior margin. The sharp outer angles of the extended flaps of M. trigonus also give the fan of this species a distinctive triangular shape ( Figure 82 ). Male and female genitalia of Maratus trigonus are very similar to those of other western Maratus including M. cristatus and M. electricus . The female is unremarkable and closely resembles the female M. cristatus . This similarity further supports our view that female specimens should not be used as holotypes for new species of Maratus .

Description of male ( Figures 77-85 ). Males were 3.5-4.2 mm in length (n=16).

The clypeus is black and almost glabrous with just a few scattered long off-white setae near the midline. The chelicerae are black and glabrous. The eye region has a background cover of grey scales, with five lines of dark red scales crossing this from front to back. One of these lines is median, and the other four extend behind each of the anterior eyes. The rest of the carapace is almost entirely black and glabrous, except for a white marginal band on either side. A short dorsomedian tract of red-brown or off-white setae may also be present behind the eye region. The PME are closer to the PLE than to the ALE.

The fan ( Figure 82 ) is distinctly triangular in shape when the angulate lobes, normally folded around the opisthosoma, are fully extended. Three tracts of tightly-packed iridescent scales project onto the fan from the anterior margin, two additional tracts of similar scales project onto the fan from each lateral margin, and one more tract of these scales lines the posterior margin of each flap. The center of the fan is occupied by a dark orange to brown figure lined with black, with a three-pointed crown of bright white scales at the posteromedian margin. This crown varies in shape from a nearly straight line with only a slight bulge at the centre ( Figure 79 :7-8) to a wave form ( Figure 80 :3) or even a trident ( Figure 80 :6). The entire figure on the fan has the appearance of a crouching, winged insect, with its legs in an anterior position (at the bottom of the fan when displayed). Although the "drawing" is quite different, the effect resembles the finely-drawn figure of an insect on the fan of M. vespa (see Otto & Hill 2016). The underside of the opisthosoma is light brown with a central brown area and a loose cover of off-white setae ( Figure 81 ). There is a small tuft of white colular setae. Below this the spinnerets are black, and the underside of each flap is black. The pedicel is remarkably flexible and can be twisted in an S-shape when the fan is elevated during courtship display ( Figure 81 :4,6-7), something that we have not seen in other Maratus species.

Legs I and II are shorter, legs III and IV longer, and legs III the longest. Legs I-II and IV are loosely covered with white to off-white setae and are indistinctly banded with areas of dark pigment. Legs III are generally black except for white setae that cover each tarsus, and a small patch of white to off-white scales on the anterior side of the distal patellar margin. There is a short fringe of relatively short white setae and the underside of each tibia and metatarsus III. From above, the pedipalps are light brown in colour and covered with long white to off-white setae. The pedipalps are unremarkable with a longer outer apex of the embolus above a shorter inner apex ( Figure 83 ).

Description of female ( Figures 86-92 ). Females ranged from 3.9-5.2 mm in length (n=12).

The clypeus is yellow-brown and translucent with long white setae oriented anteromedially over the chelicerae. The chelicerae are brown and glabrous. The pedipalps are brown with many long white setae. The face, eye region, and top of the carapace below the lateral eyes is covered with off-white or red-brown scales. In some cases a darker brown line can be seen extending over the eye region behind each AME. The sides and rear of the carapace are yellow-brown and mostly glabrous with only a few scattered scales, and there are no marginal bands on the sides.

The dorsal opisthosoma is dark brown with scattered red-brown, brown, or off-white scales and other setae. There is a wide marginal band of off-white scales and setae around the lateral sides of the opisthosoma, sometimes interrupted at the rear. Below, this band may be demarcated by darker lines. There is a small white triangle of colular scales above the grey to black spinnerets. The venter is light brown and mottled with brown spots, with a covering of shorter white to off-white setae ( Figure 89 ). The coxae, trochanters, labium and endites are translucent brown, and the sternum is black.

Legs I and II are shorter, legs III and IV longer, and legs III the longest. The brown legs are indistinctly banded with segmental rings of white scales or setae. The epigynum ( Figure 92 ) is unremarkable but typical for Maratus , with a pair of large, nearly circular fossae in front of an even larger pair of posterior spermathecae. Darker, sclerotized ducts are visible through the posterior part of each fossa.

Immatures ( Figures 93-94 ). Penultimate males ( Figure 93 ) resemble adult females but have a more distinct pattern of large, paired white spots on the opisthosoma. Penultimate females ( Figure 94 ) resemble adult females, with a wide marginal band of off-white scales around the opisthosoma.

Courtship display ( Figures 95-102 ). The male Maratus trigonus may alternate between two distinct displays. In the first display ( Figures 98-100 ) both legs III are waved up and down as the fan is waved from side to side. Movement during this display is continuous. At ~3 cycles/s legs III are first lowered more slowly (in ~0.25- 0.35s), then raised more quickly (in ~0.04- 0.12s), as the fan is rapidly rotated from side to side at a rate of ~5 cycles/s . This display always precedes physical contact and subsequent mating. The second display ( Figures 101-102 ) is quite different. In this display the fan is tilted to face the watching female and held in place as a single leg III is raised and rapidly waved up and down at a rate of ~6.2-7.8 cycles/s. In this display the extreme flexibility of the pedicel of M. trigonus is evident, as the fan is not only extended, raised and elevated, but it is also rotated and twisted away from (contralateral to) the leg III that is raised and waved. The twisted (S-shaped) pedicel during this display is shown in Figure 81 :4,6-7.

in ~ 0.08s (~3 cycles/s), as the fan was moved from side to side at a rate of ~5 cycles/s.

Mating. As in other Maratus , female M. trigonus rotate their opisthosoma by ~180° when mating ( Figure 103 ).

Habitat. The locality where Maratus trigonus was found at Mt. Lindesay is shown in Figure 104 . All spiders were found close to the summit among small shrubs or on the ground.

Figures

Figure 77. Four adult male M. trigonus. 10, Courtship display.

Figure 78. Five adult male M. trigonus. 12, Single leg-wave display.

Figure 79. Seven adult male M. trigonus. 6, 8, 11-12, Single leg-wave display.

Figure 80. Five adult male M. trigonus.

Figure 81. 1-3, Venter of three adult male M. trigonus. 4, 6-7, ventral (or posterior) view of elevated fan during courtship display. The inset rectangle in (4) is enlarged in (7) to highlight the S-curve of the pedicel. 5, Lateral view.

Figure 82. Elevated and expanded fan of eight adult male M. trigonus during courtship display, showing subtle variations in colour and pattern. Note in particular variation in appearance of the bright white "crown."

Figure 83. Medial to lateral views of the left pedipalp of six adult male M. trigonus, preserved in alcohol.

Figure 85. Three adult male Maratus trigonus preserved in alcohol.

Figure 86. Four adult female Maratus trigonus.

Figure 87. Five adult female Maratus trigonus.

Figure 88. Two adult female Maratus trigonus.

Figure 89. Ventral view of six adult female Maratus trigonus.

Figure 90. Five adult female Maratus trigonus preserved in alcohol.

Figure 91. Front view of three adult female Maratus trigonus preserved in alcohol.

Figure 92. Epigynum of eleven adult female Maratus trigonus preserved in alcohol, viewed from below. The anterior direction is toward the top of this page.

Figure 93. Eight penultimate male Maratus trigonus. The dorsal opisthosoma is more boldly patterned than it is in females, with paired spots of light brown scales demarcated by dark lines.

Figure 94. Six penultimate female Maratus trigonus. These resemble adult females.

Figure 95. Courtship display by a male Maratus trigonus.

Figure 96. Courtship display by five male Maratus trigonus. 11-13, This male was more brightly coloured.

Figure 97. Courtship display by seven male Maratus trigonus. 4, Male (at left) encountering a female. 7, Side view of the single leg III display showing how the opisthosoma is rotated and twisted away from the moving leg III.

Figure 98. Sequential frames from a 25 FPS video of courtship display by a male Maratus trigonus. Arrows indicate movement of the fan and legs relative to the previous frame. Legs III were lowered for about 0.25s, then quickly raised in ~0.04s (~3 cycles/s), as the fan was moved from side to side at a rate of ~5 cycles/s. This movement was continuous.

Figure 99. Sequential frames from a 25 FPS video of courtship display by a male Maratus trigonus. Arrows indicate movement of the fan and legs relative to the previous frame. Legs III were lowered for about 0.25s, then quickly raised in ~0.12s (~3 cycles/s), as the fan was moved from side to side at a rate of ~5 cycles/s.

Figure 100. Sequential frames from a 25 FPS video of courtship display by a male Maratus trigonus. Arrows indicate movement of the fan and legs relative to the previous frame. Legs III were lowered for about 0.25s, then quickly raised

Figure 101. Sequential frames from a 25 FPS video of courtship display by a male Maratus trigonus. Arrows indicate movement of the fan and legs relative to the previous frame. Leg RIII was continuously waved up and down at ~6.2 cycles/s.

Figure 102. Sequential frames from a 25 FPS video of courtship display by a male Maratus trigonus. Arrows indicate movement of the fan and legs relative to the previous frame. Leg RIII was continuously waved up and down at ~7.8 cycles/s.

Figure 103. Two mating pairs of M. trigonus.

Figure 104. Rocky habitat of M. trigonus at Mt. Lindesay in Western Australia. 1, Mt. Lindesay. 2, Summit of Mt. Lindesay. 3, Plateau at the summit with sculpted boulders. 4, Path leaving the summit area. Most M. trigonus were found along this path.