Maratus nambung, Ott & Hil, 2023

Ott, Ju ̈ rgen C. & Hil, David E., 2023, Maratus nambung, a new peacock spider from the southwestern corner of Australia (Araneae: Salticidae: Euophryini), Peckhamia 309 (1), pp. 1-29 : 3-27

Maratus nambung , new species

Type specimens. The holotype male (J #1) was collected 10 km SE of Cervantes , Western Australia (30.56805°S, 115.24510°E; 6 AUG 2023; Michelle Peak collector). Seven paratype males (J #2-8), and two paratype females (♀ #1-2) were collected 32 km SE of Cervantes (30.55647°S, 115.39716°E; 13 AUG 2023; Flynn Prall collector). All types will be deposited in the Western Australia Museum, Perth .

Etymology. The species group name, nambung (English, noun in apposition), is a reference to the name of the locality where this spider was found. This is an indigenous Australian word that may refer to the crooked or winding course of the Nambung River.

Diagnosis. Maratus nambung is clearly a close relative of M. bubo Otto & Hill 2016 ( Figures 1-2 ), both associated with the mungaich group of the genus Maratus (Otto & Hill 2021) . Structure of the genitalia (male pedipalp and female epigynum) is similar to that of many related Maratus in Western Australia, and of little use for identification to species. Females of M. bubo and M. nambung ( Figure 1 ) are similar and not easily separated, although females of M. nambung may be lighter in colour. The fan of male M. nambung is less rounded at the rear than that of M. bubo , the pattern of pigmented scales of this fan is different, and legs III have fringes of shorter black, rather than longer white, setae ( Figure 2 ). In addition, the scale cover of the male carapace of M. nambung is brown rather than red, and the pigmented scales of the fan of M. nambung are orange rather than bright red. M. nambung males lack the three red lines at the rear of the fan that are characteristic of M. bubo , and they also have a single black spot at the center of the fan.

Description of male ( Figures 2.5-2.6 , 3-8 ). Apart from characters mentioned in the diagnosis, males are very similar to male M. bubo . Type males (n=8) ranged from 3.95-4.55 mm in length. The front (dorsal aspect) of each pedipalp is covered with dense, long, bright white setae. The chelicerae are dark brown to black and glabrous. The clypeus has a cover of white setae, oriented medioventrally, differing from the nearly glabrous clypeus of M. bubo . The eye region is covered with brown setae, with more dull orange to brown setae extending around the eyes to the rear. Scattered setae cover the sides of the carapace (variable), and a thick band of bright white setae follows the margin of the carapace on either side. Behind the eye region a wide dorsomedian tract of white to off-white setae is usually present, although this may be rubbed off in some specimens. The PME are closer to the PLE than to the ALE.

As noted in the diagnosis, the fan of M. nambung resembles that of the male M. bubo , but differs in several key features. A central black spot is present, there is less (or no) orange on the lateral fringes, and the rear margin is less curved, and more linear, without the three red lines characteristic of male M. bubo . Individual variation in the distribution of orange setae is described in Figure 3 . In addition the pigmented scales are bright red orange rather than red, with orange to dull-orange scales in a band across the middle of the fan ( Figure 3.9 ). Ventrally, males are mostly grey to dark brown, with many long white to off-white setae, and with glabrous endites and labrum ( Figure 5 ). Legs I and II are shorter, legs IV longer, and legs III by far the longest. Legs I, II and IV are indistinctly banded, with a cover of white setae. Legs III have brown setae on the femora and patella, a black tibia and metatarsus with dense fringes of black setae, and bright white setae covering the tarsus ( Figure 3 ). Detailed structure of the pedipalp closely resembles that of many other Maratus from southwestern Australia, with the single coil of the embolus retrolaterally (or apically) divided, with a distinct ventral projection or "tooth" of the outer apex ( Figure 8 ).

Description of female ( Figures 1.4-1.6 , 9-12 ). Type females (n=2) ranged from 4.65-5.07 mm in length. These are not readily distinguished from the female Maratus bubo ( Figure 1.1-1.3 ), but may have a more dense cover of off-white setae. The chelicerae are brown and mostly glabrous, with several medial off-white setae. The clypeus is covered with long white to off-white setae, dorsomedially directed above the chelicerae. Off-white or brown to dull orange setae cover much of the carapace, including the eye region, but are more sparse on the sides of the carapace. Unless rubbed, a distinct dorsomedial thoracic tract of off-white setae should be present behind the eye region, but there is no distinct marginal band as in the male. The PME is closer to the PLE than to the ALE.

The opisthosoma is covered with brown to grey and off-white setae, and distinct marginal bands may or may not be present. A pattern of five small spots comprised of light brown or off-white setae may be seen on the dorsum ( Figures 1.6 , 9.7 , and less distinctly in 9.3). The underside of the opisthosoma is covered with off-white or white setae, with indistinct mottling. The coxae and endites are mostly glabrous and translucent, grey to light brown. The sternum and labium are darker grey to brown, glabrous except for long white setae projecting from the sides and rear of the sternum ( Figure 10). Legs I and II are shorter, legs IV longer, and legs III the longest. All legs are similar in colour, with a covering of off-white setae and indistinct banding. The epigynum ( Figure 12 ) is variable but similar to that of many other Maratus species. Similar variation in the structure of the epigynum was previously described for M. bubo (Otto & Hill 2016).

Courtship display ( Figures 13-21 ). The courtship display of males was observed and recorded with 25fps and 100fps video when they were placed in a naturalistic setting in the laboratory. The higher speed (100fps) is much preferred, as it can capture the more rapid movements of the male.

Like many Maratus , M. nambung males perform either unilateral ( Figure 13 ) or bilateral ( Figures 14-15 ) semaphore displays, at times when the male appears to lose sight of a female in the vicinity, and at times when a female has turned away from the display. These are considered to represent advertisements. The bilateral display may be symmetrical or assymetrical.

The fan dance ( Figures 16-21) represents the primary display used by a male once the attention of a female has been secured. In this dance the male moves in a series of steps from side to side while facing the female, with the fan fully expanded and elevated, and legs III extended. This display combines side stepping (~3 steps/s or 3Hz) with side-to-side waving or rotation of the elevated fan (10-20 L/ R cycles/s or 10-20Hz) at a relatively low amplitude (2-16°). In some cases the pedipalps are also moved up and down (U/D cycles at ~3-4 Hz). During this display movement of legs III is variable. The elevated legs III may be held in place, or they may also be waved to a variable extent. In some cases they are periodically flexed at the tibiometatarsal joint (metatarsal flexion), and then brought together at the midline ( Figure 20 , ~4.5 Hz).

Previously (Otto & Hill 2016) we described the courtship display of Maratus bubo . Although related to M. nambung , the fan dance of M. bubo is quite different in several important ways. First, the male M. bubo flexes both legs III at the patellotibial joint and holds this position without leg movement, bracketing the fan in a manner characteristic of M. mungaich and many other members of the mungaich group. L/ R rotation of the fan was also slower (~6 Hz), as was side-stepping (~1.5/s). Although not measured, the amplitude of fan rotation by M. bubo was clearly much greater.

Distribution and habitat. Localities where Maratus nambung and its close relatives have been found are shown in Table 1 and Figure 22.

Figure 22. Localities where Maratus nambung and its close relatives (see Figures 1-2 ) have been found. The detailed map at right, prepared with QGIS, represents the inset rectangle at lower left in the larger map of Australia.

The habitat where Maratus nambung was found is shown in Figure 23 . It is likely that this species can be found in other uncleared areas between Nambung National Park and the Brand Highway.

Figures

Figure 3. Fan dance by the type males for Maratus nambung, showing variations in the scale pattern of the fan. 9, Across the fan in the middle (inset rectangle) most pigmented scales are dull orange to orange, contrasting with the red-orange scales on other parts of the fan. In male M. bubo (Figure 2.1-2.2), all of these scales are bright, scarlet red. As shown here, the detailed pattern of pigmented orange scales varies somewhat between individuals. For example, in males 1 and 4-5 there is a small orange spot behind the central black spot. The amount of orange colour at the fringed lateral margins of the fan also varies, and is lacking in some individuals (e.g., 3-6, 8).

Figure 4 (continued on next page). Type males for Maratus nambung.

Figure 5. Type males for Maratus nambung, ventral view under glass.

Figure 6 (continued from previous page). Type males for Maratus nambung, in alcohol.

Figure 7. Type males for Maratus nambung, in alcohol. 1-8, Frontal view. 9-10, Detailed views of scales covering the fan (flaps retracted).

Figure 8 (continued on next page). Medial to lateral views of the left pedipalp of type males for Maratus nambung, in alcohol.

Figure 9. Paratype females for Maratus nambung. The first of these (1-5) is more brown and less grey, with more rubbing on the dorsum.

Figure 10. Ventral views of paratype females for Maratus nambung, under glass.

Figure 11. Paratype females for Maratus nambung, in alcohol.

Figure 12. Ventral view of the epigynum of the paratype females for Maratus nambung, in alcohol. Note variation in the relative width of the septum (between the fossae), and the size of the spermathecae.

Figure 13. Selected frames (100fps) from a video of display by a male Maratus nambung. This is a unilateral advertisement display, including slow movement of an extended leg III and some up and down movement of the pedipalps to expose and then to cover the dark, glabrous chelicerae.

Figure 14. Selected frames (100fps) from a video of display by a male Maratus nambung, facing a female. This shows transition, with retracted flaps and lowering of the opisthosoma (1-4), from the fan dance to bilateral advertisement involving semaphore movements of the extended legs III. These movements were sometimes assymetrical (e.g., 11-13), and sometimes symmetrical (e.g. 9-10, 14-15).

Figure 15. Selected frames (100fps) from a video of display by a male Maratus nambung, facing a female. This shows periodic flexion of the metatarsi III (arrows) during (1-7) and after (8-16) transition from the fan dance to advertisement.

Figure 20. Selected sequential frames (100fps) from a video of a fan dance by a male Maratus nambung, facing a female, as viewed from the rear. During this sequence the male was moving toward the left. Here the fan was waved (arrows) at a low amplitude (2-16°) at 11 L/R cycles/s (11 Hz).

Figure 23. Localities where Maratus nambung was found. 1-2, Locality #4 in Table 1. 3-8, Locality #3 in Table 1. 7-8, Males on dried plants near the ground in their native habitat. Photo credits: 1-2, Flynn Prall; 3, Jürgen Otto; 4-8, Michelle Peak.

Figure 1. 1-3, ♀ Maratus bubo Otto & Hill 2016. 4-6, ♀ M. nambung, new species. The female M. nambung has more cover of white to off-white scales, but like M. bubo has a characteristic pattern of five white spots at the center of the dorsal opisthosoma (identified by green rectangles in 1.3 and 1.6).

Figure 2. 1-2, J Maratus bubo Otto & Hill 2016. 3-4, J M. cf. bubo, undescribed. Except for the bright red colour of pigmented scales on the fan, this form appears to be closer to M. nambung than to M. bubo. 5-6, J M. nambung, new species. M. bubo has a large fringe on tibia-metatarsi III, with a fan that is more rounded at the rear and marked in that place by three red lines. The other two species lack this fringe, but have a shorter fringe of black setae. The carapace of M. nambung (5-6) has a cover of brown (rather than dull red) scales, and pigmented scales of the fan are orange to red-orange rather than bright red, with a distinct black spot at the center.