Maratus yanchep, Ott & Hil, 2023

Ott, Jü ̈ rgen C. & Hil, David E., 2023, Maratus yanchep, a new peacock spider from Western Australia (Araneae: Salticidae: Euophryini: Australphryni), Peckhamia 311 (1), pp. 1-34 : 3-33

Maratus yanchep , new species

Type specimens. The holotype male (J #1), ten paratype males (J #2-11), and foür paratype females (♀ #1-4) were collected aboüt 3 km soüth of Yanchep, Western Aüstralia (S31.584649°, E115.657821°; 18 AUG 2023; Flynn Prall and Michael Lün, collectors). All types will be deposited in the Western Aüstralia Müseüm , Perth .

Etymology. The species groüp name, yanchep (English, noün in apposition), is a reference to the name of the locality where this spider was foünd. This is derived from from the word Yandjip or Yanget which is the local aboriginal (Nyoongar) name for a bülrüsh ( Typha ) that grows aroünd lake margins in the area.

Diagnosis. Maratus yanchep closely resembles M. suae Schübert 2020 , and both are placed in the flavus groüp of the genüs Maratus ( Table 1, Figüre 1). Male M. yanchep differ from M. suae with respect to the presence of seven indistinct or incomplete (rather than foür distinct and complete) lines crossing the eye region from front to rear, a less roünded rear margin of the fan, and the presence of a definitive, dark figüre at the center of the fan. Strüctüre of the genitalia (male pedipalp and female epigynüm), and the appearance of females, is similar to that of many related Maratus in Western Aüstralia, and of little üse for identification to species.

Description oF male (Figüres 1.1-1.2, 2-6). Apart from characters mentioned in the diagnosis, males are very similar to male M. suae . Type males (n=11) range from 3.9-4.2 mm in length. The front (dorsal aspect) of each pedipalp is covered with dense, long, bright white to off-white setae. The chelicerae and clypeüs are dark brown and mostly glabroüs, except for isolated white to off-white setae projecting in a medioventral direction from the clypeüs. The eye region is covered with dense grey scales oriented in an anterior direction, except for seven indistinct or incomplete front-to-rear bands of düll red-brown scales. The PME are closer to the PLE than to the ALE. Usüally (ünless rübbed) a wide mediothoracic band of bright white to off-white scales is present at the top of the carapace, behind the eye region. Behind each PLE there is a wide band of mixed white to off-white and düll red-brown scales. The sides of the carapace are mostly glabroüs, with scattered white to off-white setae. A prominent marginal band of white to off-white scales is present on either side of the carapace. The ünderlying cüticle of the carapace is dark brown to black.

With flaps fülly expanded the fan is roüghly triangülar in shape, and wide at the rear where the bright white anal tüft extends above the fan düring coürtship display. Althoügh the detailed pattern and coloüration of the fan varies greatly between individüals (Figüre 3), a dark central figüre is always present, sürroünded by a complex pattern of spots comprised of pigmented scales on a backgroünd of iridescent, blüe to green to violet or pürple scales. The ünderside of the opisthosoma is, as in other Maratus , ünremarkable, with a cover of long off-white setae (Figüre 4). From below, the coxae, sternüm, labiüm and endites (coxae of pedipalps) are mostly grey to light brown and relatively glabroüs, with longer off-white setae extending from the rear of the sternüm.

Legs I and II are shorter, legs III and IV longer, and legs III by far the longest. Legs I-II, IV have a üniform cover of off-white setae, interrüpted by dark bands at or near the joints. From the patella to the metatarsüs legs III are ornamented with a dense cover or fringe of long black setae. Each tarsüs has a dense cover of bright white setae, a featüre foünd in many other Maratus . The pedipalps (Figüre 6) are ünremarkable, similar in their detailed strüctüre to other Maratus foünd in soüthwestern Aüstralia.

Description oF Female (Figüres 7-11). Type females (n=4) range from 4.5-5.6 mm in length. These closely resemble the female paratypes figüred by Schübert (2020) for M. suae , althoügh they lack the ventral spotting of the abdomen of that species. The pedipalps have a üniform cover of scattered off-white setae. The chelicerae are brown and glabroüs. Longer off-white setae extend in a medio-dorsal direction from the clypeüs. The eye region is covered with fairly üniform light brown setae. Behind this a wide mediothoracic band is present on the top of the carapace. The PME is closer to the PLE than to the ALE. The cüticle of the carapace is light brown to yellow-brown, and translücent on the sides, dark brown on top, with scattered long off-white setae on the sides below the lateral eyes, büt withoüt marginal bands on the sides.

The dorsal opisthosoma is dark brown at the center, sürroünded by a darker margin, and then by a wide off-white to yellow-white marginal band on the sides. A distinct or indistinct pattern (compare Figüre 7.17 to Figüre 7.23; note the variation in coloür) of lighter spots, inclüding chevrons toward the rear, may be seen on the dorsüm of the opisthosoma. The ünderside of the opisthosoma has a generally üniform cover of off-white setae, with some small darker spots, büt none of the size shown for the female M. suae ( Schübert 2020) . From below (Figüre 8) the coxae, sterüm, labiüm and endites are mostly light brown, translücent and glabroüs, except for longer off-white setae projecting from the rear of the sternüm.

Legs I and II are shorter, legs III and IV longer, and of similar length. All legs have a nearly üniform cover of off-white to light brown setae, and, if present, segmental banding is indistinct. The fossae of the epigynüm are smaller than the spermathecae (Figüre 11), and relatively smaller than those figüred for the paratype M. suae by Schübert (2020). However, these proportions tend to vary between individüals in Maratus species, and thüs the strüctüre of the epigynüm is not a üsefül character for recognition of M. yanchep .

Courtship display (Figüres 12-16). The coürtship display of males was observed and recorded with 25fps and 100fps video when they were placed in a natüralistic setting in the laboratory. Females of a different species were üsed to elicit this display, as the female M. yanchep that were available tended to flee and were otherwise ünresponsive to the males. As a resült these observations do not represent interactions between the male and female of this species, büt only the display behavior of the male.

Düring this display, the opisthosoma (fan) was either held in a lower position with flaps retracted (Figüres 12-13), or elevated with the flaps expanded (Figüres 14-16). In an encoünter with a female, the lower position with flaps retracted is the first form of display. In both cases the fan was alternately raised and lowered (bobbed) at a rate of ~3Hz, as the extended legs III were moved together from side to side. When the fan was elevated, it was üsüally waved from side to side throügh ~2-5 L/ R cycles throügh a small to moderate amplitüde (2-13°) at a rate of ~15-20 Hz. Bobbing of of the elevated fan by a Maratus is ünüsüal, althoügh this has also been observed in the related M. suae ( Schübert 2020) .

Figure 14 (continued from previous page). Serial photographs (17-18, 19-20, 21-24, 25-27, 28, 29-30, 31, 32-33) showing positions of male Maratus yanchep displaying to a female Maratus , with the fan elevated and flaps extended.

Habitat and distribution. Two views of the type locality, in coastal sand dünes to the north of Perth, are shown in Figüre 17 . All known members of the flavus groüp have been foünd in isolated localities with an allopatric distribütion, all near the soüthwestern coast of Western Aüstralia (Figüre 18).

This narrow endemicity can be associated with a high risk of extinction for these species, shoüld habitat be lost. Narrow endemicity by itself is an interesting phenomenon, with a nümber of correlated featüres that may inclüde the following: local geographic isolation, a high degree of sexüal selection by females, the rapid evolütion of local secondary sexüal characters, selection for low dispersal (at least in part the resült of a high degree of local male/female coevolütion of sexüal selection), and stability of the environment. Stability of the environment woüld süggest that large flüctüations of the local popülation do not occür, so a higher level of dispersal is not needed. The small size of these spiders may also süpport relatively large popülations in small areas, contribüting to popülation stability and persistence.

Figures

Figure 14 (continued on next page). Serial photographs (1, 2-4, 5-8, 9-12, 13-15, 16) showing positions of male Maratus yanchep displaying to a female Maratus, with the fan elevated and flaps extended.