Maratus cristatus, 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 : 2-25

Maratus cristatus , new species

Type specimens. The holotype male (♂ #1), 12 paratype males (♂ #2-12, 21), and 10 paratype females (♀ #13-20, 22-23) were collected 34 km west of Denmark (34.96796667°S, 116.9794333°E, 11 OCT 2016, coll. J. Otto). Of these one male (♂ #21) and three females (♀ #17-18, 22) 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 ( cristatus, Latin , m., adjective, English translation crested or tufted) refers to the presence of distinctive tufts of long white setae along the posterior margin of the male fan.

Diagnosis. M. cristatus is close to M. vespa Otto & Hill 2016 with respect to male and female genitalia, the presence of many long bristle-like setae on legs III, and general features of the courtship display which includes the close approach of an attentive female. We place both species in a new clade, the vespa group. Male M. cristatus are readily identified by the ornamentation of their fan which includes eight tufts of long white setae along the posterior margin, four of which are visible from above when the flaps are folded. Females are variable and resemble those of other Maratus species but tend to have three dark lines projecting toward the rear of the dorsal opisthosoma.

Description of male ( Figures 2-9 ). Males were 3.5-4.2 mm in length without posterior tufts, 3.7-4.5 mm in length with tufts (n=13).

There are two distinct colour forms, one with mostly white setae on the carapace and legs, and the other with mostly light brown setae. Otherwise they appear to be identical. The clypeus and chelicerae are black and mostly glabrous with longer white setae directed anteromedially near the median ( Figure 2 :8). White setae cover the black carapace below the anterior eyes. The eye region has a background covering of either white, grey, or light brown scales. Dark red setae can be seen along the dorsal margins of the anterior eyes. Two broad, dark red stripes extend to the rear of the eye region, and usually there is a third, median stripe of the same colour but variable width between these. The PME are closer to the PLE than to the ALE. The posterior eyes are surrounded by setae that match the background colour of the eye region, and a variable but scattered cover of white or light brown setae may extend further along each side of the carapace beneath the eye region. The rear of the carapace is black and mostly glabrous with a median tract of white setae. There is a narrow marginal band of white setae along each side of the carapace.

The dorsal opisthosoma ( Figure 2 :1,5) bears a distinctive lattice pattern of dull red to red-orange or orange ( Figure 5 :8) pigmented scales, bordered by black to the rear, on a background of blue-green iridescent scales. Lateral flaps that are extended during courtship display are dark purple and lobate. Long white bristle-like setae extend forward over the pedicel from the anterior margin. Extending beyond the rear margin are eight prominent tufts of long white setae, four visible from above when the flaps are folded around the sides of the opisthosoma. The lateral pair of these tufts can be concealed beneath the flaps ( Figure 2 :2, Figure 3 :8) or fully extended ( Figure 2 :5) during display. The venter of the opisthosoma ( Figure 2 :2) is covered with white scales on a dark brown background. The spinnerets and the underside of the flaps are black. Above the spinnerets is a small tuft of white colular setae that can be visible above the fan during display ( Figure 2 :5).

Legs I and II are shorter than legs III and IV, and legs III are by far the longest. The pedipalps and all legs are covered with either white or light brown setae. These setae are long and bristle-like on the patella, tibia, and tarsus of each leg III ( Figure 2 :4-5,7). The embolus of the pedipalp (Figure 8) has two pointed apices, the outer one heavier and longer.

Description of female ( Figures 10-16 ). Females ranged from 4.7-5.6 mm in length (n=10).

The clypeus and chelicerae are translucent, dark yellow. Long white setae project anteromedially over the glabrous chelicerae. The eye region is variably covered with off-white to red-brown setae, sometimes interrupted with linear patterns of lighter setae or dark areas of the exposed carapace. Behind the eye region two black bands of exposed cuticle surround a median tract of off-white to red-brown setae that extends half-way to the rear margin of the carapace. The sides of the carapace are variably covered with setae of the same colours, mostly dorsally and below and behind each PLE. Toward the bottom the sides of the carapace are mostly glabrous, and there is no marginal band on either side. The PME are slightly closer to the PLE than to the AME.

The dorsal opisthosoma is generally dark brown with a wide off-white band on either side. Indistinct lines including a median line of lighter setae may be present toward the front. A set of three dark brown lines may extend toward the rear ( Figure 10 :5, Figure 11 :6,9,12). There is a small triangular tuft of white colular setae above the black spinnerets. The venter is light brown with a moderate cover of uniform offwhite setae ( Figure 13 ).

Legs I and II are shorter than legs III and IV, and legs III are the longest. All legs are brown to dark brown and are covered with scattered off-white setae. Typical for Maratus , the epigynum has a pair of large, roughly circular fossae (or fenestrae) anterior to a pair of large posterior spermathecae ( Figure 16 ). Variably sclerotized ducts anterior to the spermathecae can be seen through the posterior half of each fossa.

Immatures ( Figure 17 ). Penultimate male M. cristatus resemble adult females but have a distinctive pattern of dark lines radiating in all directions from the dark brown center of the dorsal opisthosoma ( Figure 17 :1-3). Penultimate females ( Figure 17 :4-7) more closely resemble adult females but may also exhibit some of these radiating dark lines on the dorsal opisthosoma. As in adult females, a set of three dark lines may project from the central, dark brown area of the opisthosoma toward the rear, and a wide marginal band is present on either side.

Courtship display ( Figures 18-27 ). The courtship display of Maratus cristatus resembles that of M. vespa ( Otto & Hill 2016) in that the female approaches the courting male very closely ( Figure 24 ) and turns from side to side to follow movements of the male fan. In both species legs III are elevated and held in place as the fan is moved from side to side. In M. cristatus we observed two modes of fan rotation. In the first mode ( Figures 21-24 ) the fan was rotated from side to side through an angle of ~16-23° at 5.6-6.5 cycles/s. In the second mode ( Figures 25-27 ) the fan was rotated only ~1-3° at 1.9-3.8 cycles/s.

Mating. As in other Maratus , mating M. cristatus females rotate their opisthosoma through an angle of about 180° ( Figure 28 ).

Habitat. The type locality for Maratus cristatus is shown in Figure 29 . All spiders were found along a sandy track adjacent to an ephemeral swamp and near a small body of water, either on twigs strewn along the edge of the track or on sedges.

Figures

Figure 2. Two adult male Maratus cristatus with light-brown setation. 1, Anterior view of extended fan during courtship display. 2, Ventral view of opisthosoma during display showing retracted lateral tuft beneath each lobe of the fan. The white colular tuft is found in many Maratus species. 5, Display with lateral tufts of the fan fully extended. 8, The black cuticle of the carapace is almost fully exposed on the clypeus. Background scales in the eye region of the first male (♂ #1) are light brown and corresponding scales of the second male (♂ #3) are grey.

Figure 3. Five adult male Maratus cristatus. All except ♂#5 (2) have white setation. 7, The sides of the black carapace are glabrous behind the posterior eye row. 8, View of the opisthosoma showing how the outer pair of white tufts can be retracted beneath the flaps.

Figure 4. Three adult male Maratus cristatus.

Figure 5. Six adult male Maratus cristatus. 8, This male had brightly-coloured orange to red-orange scales on the fan, in contrast to the dull red that appeared to be more common.

Figure 6. Three adult male Maratus cristatus preserved in alcohol.

Figure 9. Frontal view of three adult male Maratus cristatus preserved in alcohol.

Figure 10. Six adult female Maratus cristatus.

Figure 11. Five adult female Maratus cristatus.

Figure 12. Adult female Maratus cristatus.

Figure 13. Ventral view of six different adult female Maratus cristatus. The venter of the opisthosoma can be relatively unmarked (4), mottled (5), or striped (1).

Figure 15. Eight adult female Maratus cristatus preserved in alcohol, with frontal views (9-14).

Figure 16. Ventral view of the epigynum of ten different adult female Maratus cristatus preserved in alcohol. The posterior spermathecae are larger than the fossae. Width of the septum and sclerotization of the ducts anterior (toward the top of the page) to the spermathecae are variable.

Figure 17. Penultimate male (1-3) and penultimate female (4-7) Maratus cristatus. 1-5, Here as in subsequent figures each juvenile spider carries the same identifier (e.g., ♂ #21) as the corresponding adult.

Figure 18. Positions assumed during courtship display by a male Maratus cristatus. 8-9, Here the fan was slightly lower and the tuft of white setae at the lateral margin of each lobe was retracted.

Figure 19. Positions assumed during courtship display by two male Maratus cristatus. 1, Display with a partly lowered fan. 2- 9, Display with a fully extended fan. 6, Notice the position of the posterior tufts of the fan behind the long setae of leg III when the fan is tilted far to one side.

Figure 20. Positions assumed during courtship display by four male Maratus cristatus.

Figure 21. Consecutive video frames (25 FPS) showing display by a male Maratus cristatus in front of a female. Arrows indicate rotation of the fan relative to each previous frame. In this example the fan was rotated through about 23° at a rate of ~6.5 cycles/s.

Figure 22. Consecutive video frames (25 FPS) showing display by a male Maratus cristatus in front of a female. Arrows indicate rotation of the fan relative to each previous frame. In this example the fan was rotated through about 16° at a rate of ~6.5 cycles/s.

Figure 23. Consecutive video frames (25 FPS) showing display by a male Maratus cristatus in front of a female. Arrows indicate rotation of the fan relative to each previous frame. In this example the fan was rotated through about 20° at a rate of ~5.6 cycles/s.

Figure 24. Selected video frames (25 FPS) showing sequential positions as an attentive female (foreground) turned to follow the display of a male Maratus cristatus.

Figure 25. Sequential video frames (25 FPS) showing display by a male Maratus cristatus in front of a female. Arrows indicate rotation of the fan relative to each previous frame. In this sequence the fan was rotated through about 1-2° at a rate of ~1.9 cycles/s.

Figure 26. Sequential video frames (25 FPS) showing display by a male Maratus cristatus in front of a female. In this sequence the fan was rotated through about 1-2° at a rate of ~3.8 cycles/s.

Figure 27. Sequential video frames (25 FPS) showing display by a male Maratus cristatus in front of a female. In this sequence the fan was rotated through about 2-3° at a rate of ~3.6 cycles/s.

Figure 28. Mating positions of Maratus cristatus.

Figure 29. Maratus cristatus was found along this sandy track west of Denmark in Western Australia, adjacent to what appeared to be an ephemeral swamp.