Maratus pinniger, Ju & Otto & Hill, 2022

Ju, Otto, C. & Hill, David E., 2022, Maratus pinniger, a new peacock spider in the vespa group from southwestern Australia (Araneae: Salticidae: Euophryini), Peckhamia 262 (1), pp. 1-30 : 4-27

Maratus pinniger , new species

Type specimens. The holotype male (♂ #1), six paratype males (♂ #2-7), and one paratype female (♀ #1) were collected in coastal sword-sedge ( Lepidosperma gladiatum ) in a damp swale area surrounded by Jarrah / Marri forest, in Blackwood State Forest , Western Australia ( Figure 2 ; S33.945174°, E 115.302561°, 16 OCT-10 NOV 2021, coll. Paul Winthrop). All types will be deposited in the Western Australian Museum , Perth .

Etymology. The species group name, pinniger (Latin, adjective, m.), means pinnate or feather-bearing, an apt description for the fan flaps displayed by the male of this species, bearing specialized setae that resemble long "feathers." Pinnager (or pennager) is also a medieval English occupational surname for a pennant or ensign-bearer.

Diagnosis. Females resemble other females in the vespa group, and related groups in southwestern Australia, and examination of the male is necessary for identification. The male pedipalp also resembles that of other members of the vespa group and related groups. The male is closest to M. fletcheri in appearance ( Figure 1 ), but can be reliably separated from that species by the presence of larger areas of iridescent scales at the rear of the fan, and the presence of multiple, long, feather-like setae (pinnae) extending beyond the margin of each lateral flap of the fan. The colour of scales that cover much of the body and legs (brown in M. fletcheri , white in M. pinniger ) may not be a reliable indicator, as the related M. cristatus ( Figure 1 :2-3) has both colour forms.

Description of male ( Figures 3-9 ). Males (n=7) ranged from 3.3-3.8 mm in length. The chelicerae are black, glabrous. The clypeus is covered with many long white-grey setae, directed toward the front above the chelicerae. The carapace is black, mostly glabrous, with a cover of grey scales in the eye region, where three interrupted bands of brown or dark red-brown scales can be seen, one at the median and one on either side of this. Another irregular or interrupted band of brown or dark red-brown scales runs on either side of the carapace, through the lateral eyes. Small spots comprised of white-grey scales are present just behind each PLE, and in a median thoracic position. The margin of the carapace is lined with white-grey scales or setae. Each PME is distinctly closer to the ipsilateral PLE than to the ipsilateral ALE.

Long, stout or erect black and white setae project from the anterodorsal opisthosoma. The fan bears a distinctive pattern ( Figures 4 , 6) comprised of iridescent blue-green and pigmented red to brown scales, with long feather-like setae (pinnae), some> 0.5 mm in length, extending beyond the curved posterior margin of each flap. The anterior margin of each flap also has a fringe of white-grey setae. Behind the fan, the posterodorsal opisthosoma is black, with a median group of mostly white, scattered scales and, behind this, the anal tuft of white setae ( Figure 4 ) that is typically found in Maratus species. The spinnerets are black. Below ( Figure 9 ), the opisthosoma is brown, with a covering of white setae, and the coxae, sternum, endites, chelicerae and pedipalps are mostly dark-grey or black.

The legs are generally black to brown in colour, legs I and II of about the same length and shortest, legs III longest. Legs I-II and IV are distinctly to indistinctly banded with white scales or setae. Legs III are heavily fringed with long white setae, dorsally on the femur, and mostly ventrally from the patella to metatarsus. Tarsus III is covered with bright white setae. Femora I and II are thicker, each with several black spots on glabrous, light brown cuticle when viewed from below.

The pedipalp, with a single tooth below the apex of the outer ring of the embolus ( Figure 8 ), is typical for the vespa group, as well as the related flavus, linnaei, and mungaich groups of southwestern Australia ( Otto & Hill 2021), and appears to be of no use for identification to species.

Description of female ( Figures 10-11 ). Body length (n=1) 5.4 mm. In general the cuticle of the female is light-brown to brown and translucent, with darker brown banding on the legs, and dark brown on the dorsal carapace and opisthosoma. The paturon of each chelicera is mostly glabrous, with a sparse covering of white setae. The pedipalps are light-brown with a cover of projecting white setae. From the face, below the anterior eyes, and the clypeus a number of long white setae extend to the front. These are not as dense as they are in the male. Both the carapace and opisthosoma have scattered white and redbrown scales on a dark brown background dorsally, with bands of mostly white scales on either side. Except for a line of white setae in front, above the chelicerae, the margins of the carapace are almost entirely glabrous, without the marginal band seen in the male.

The white bands on the lateral margins of the dorsal opisthosoma do not meet at the rear. A small triangular anal tuft of white scales is present, above the brown spinnerets. The venter of the opisthosoma is light-brown, with many small brown spots, with a fairly uniform cover of white setae. Coxae, sternum, endites, chelicerae and pedipalps are mostly light brown and glabrous from below. Legs I and II shorter and of similar length, legs III and IV also of similar length but longer. From above all legs are distinctly to indistinctly banded with alternating white setae and exposed dark cuticle.

The epigynum ( Figure 11 :6) is typical for the group, with a smaller fossa in front of each large posterior spermatheca, and more sclerotized ducts visible through the posterior half of each fossa.

Courtship display ( Figures 12-20 ). All observations of courtship took place under simulated natural conditions in the laboratory. Like other Maratus , male M. pinniger may raise one or both legs III to gain the attention of a nearby female ( Figures 3 :13, 12). Display may include slow, intermittent movement of legs III with occasional flexing at the tibiometatarsal joint. Advertising males could also extend legs III in a V-shaped configuration, and wave the elevated fan in a median position ( Figures 13 , 20 :1-2).

As is the case for other members of the vespa group, a close approach of the female to examine the male led to rotation of the fan from one side to the other behind legs III, held in more of a "calipers" position ( Figures 14-20 ). During this display, the pedipalps, separated to reveal the glabrous black chelicerae, and legs III of the male were held in a stationary position. As with the previous (advertisement) display, movement of the fan was fairly continuous when observed with 120 fps video, involving left-right cycles of side to side movement at 5-9Hz, accompanied by "bobbing" or vibration of the opisthosoma at ~50Hz. Slower (2-3Hz) extension-retraction cycles of each lateral flap, as it was was turned toward the female at one side or the other, were also observed.

Figure 16 (continued on next page). Serial frames from a 120fps video of courtship display by a male Maratus pinniger . 1-4, 1.5 cycles of left-right fan rotation at 5.6Hz. 5-10, 2.5 cycles of flap retraction at 2Hz. 12-43, 16 left-right cycles of fan rotation as the fan was raised to an elevated position, at 6.9Hz.

Habitat. Maratus pinniger was found on coastal sword-sedge ( Lepidosperma gladiatum ) in a damp swale area surrounded by Jarrah/Marri forest, in Blackwood State Forest, Western Australia ( Figure 21 ).

Figures

Figure 1. Adult males representing eight species in the vespa group. 2-3, Both white and tan versions of M. cristatus were found at the same locality. 4, M. fletcheri most closely resembles M. pinniger, new species (6). 7, M. tortus is the only species in this group that twists the fan to display each "feathered" flap between legs III, as shown here. 8-9, Note the similar pattern on the fan of these two distinct species. M. vespa is the type species for the group. Photo credit: 4, © Adam Fletcher, used with permission.

Figure 2. Known distribution of members of the Maratus vespa group, all endemic to forested areas with relatively high rainfall in southwestern Australia. To date these species appear to be parapatric, i.e., without any overlap in distribution. Note the proximity of M. fletcheri (5) and M. pinniger (9, highlighted in yellow) type localities. Records for these narrowly endemic species are scarce. For most of this area, no records exist for the group.

Figure 3 (continued on next page). Living type males for Maratus pinniger.

Figure 4. Detailed views of the fan of living type males, Maratus pinniger.

Figure 5 (continued on next page). Type males in alcohol, Maratus pinniger.

Figure 7. Anterior view of type males in alcohol, Maratus pinniger.

Figure 8 (continued from previous page). Medial to lateral views of left pedipalp for type males in alcohol, Maratus pinniger.

Figure 9. Ventral view of living paratypes, male Maratus pinniger.

Figure 10. Living female paratype, Maratus pinniger.

Figure 11. Female paratype, Maratus pinniger. 1-5, Submerged in alcohol. 6, Ventral view of epigynum (anterior toward top of page). 7, Ventral view of living spider.

Figure 12. Sequential photographs showing advertisement with a single raised and extended leg III by a male Maratus pinniger. Note the long setae on this leg, and the thick white fringe of the dorsal femur in particular.

Figure 13. Serial frames from a 120fps video of courtship display by a male Maratus pinniger. Lateral movement of the elevated fan relative to the preceding frame is indicated with an arrow. Movement was fairly constant, at a rate of ~4.3Hz (12.5 left-right cycles in 2.9s). There was little movement of the extended legs III, or the pedipalps, during this display. For each numbered frame (1-25) in this series (and in other series shown below), the sequential frame number (f), time elapsed since the previous frame (+), and the total elapsed time is shown.

Figure 14. Two series (1-8, 9-10) showing the female Maratus pinniger (at right) following the side to side movement of the fan by a male engaged in the final stage of courtship. As each male turned the fan to display the "feathered" flap on either side, alternating from left to right, the female, at a distance of 4-5 mm, turned to follow this movement.

Figure 16 (continued from previous page). Serial frames from a 120fps video of courtship display by a male Maratus pinniger. 12-43, 16 left-right cycles of fan rotation as the fan was raised to an elevated position, at 6.9Hz. 32-42, 4.5 cycles of right fan retraction and extension, with the fan in a median position, at 6.1Hz. 44-50, 3 cycles of fan extension and retraction at 2.0Hz. Continuous movement was accompanied by low-amplitude bobbing or vibration of the opisthosoma at ~50Hz.

Figure 20. Photographs and sequences (1-2, 3, 4-6, 7-9) of two male Maratus pinniger engaged in courtship display. 1-2, Legs extended in a V-shaped configuration as the fan was rotated from side to side in a central position. 3, Female (in foreground) looking directly at the "feathered" left flap of the male. 4-6, Typical positions of the final phase of courtship, with the fan held in a lower position, even when centered. Note extension of legs IV to the rear. 7-9, Here the fan was elevated in the center position, apparently as an advertisement to obtain the attention of the female.

Figure 21. Habitat of Maratus pinniger. Females (5) and males (6) were found on low vegetation in an open swale, near Jarrah/Marri forest. Photographs © Paul Winthrop, used with permission.