Cruralonga milnerii, Shaw, 2025

Cruralonga milnerii sp. nov.

Figs 4 View Figure 4 - 16 View Figures 15, 16 , 18 View Figures 17, 18 - 22 View Figures 19–22

Holotype.

SAMA J 25686 .

Type-locality.

Australia, South Australia, Cave 5 N-23, Yalata Indigenous Protected Area; 1 Dec. 2021 to 9 Mar. 2022, almost dark zone, ca. 20 m at 110 degrees from southernmost window; unbaited pitfall trap A; S. Milner, A. Stempel, M. D. Shaw leg.

Type-specimen.

Holotype • larva; SAMA J 25686 ; mounted on microslide in Hoyer’s medium; Original labels: “ NEOTROMBIDIIDAE / Cruralonga milnerii sp. nov. / Shaw, 2025 / Holotype / larva SAMA J 25686 ” “ South Australia, Cave 5 N-23 / Yalata Indigenous Protected / Area, almost dark zone / ca. 20 m at 110 degrees from / southernmost window / 1 Dec 2021 to 9 Mar 2022 / S. Milner, A. Stempel, M. Shaw / unbaited pitfall trap A / Yalata Bush Blitz 2021 ” .

Paratypes • SAMA J 25681 ; larva; Cave 5 N-12 , Yalata Indigenous Protected Area; 30 Nov. 2021 to 10 Mar. 2022; dark zone, trap B, sardine-baited pitfall trap; Steve Milner, Andrew Stempel, Matthew Shaw leg. • SAMA J 25682 ; larva; Cave 5 N-22 , Nullarbor Wilderness Protected Area, LH wall southside, ca 40 m from entrance lip; 29 Nov. 2021 to 6 Mar. 2022; Steve Milner, Andrew Stempel, Matthew Shaw leg.; pitfall trap A, sardine-baited; 19.8 degrees C, 73 % RH • SAMA J 25688 ; larva; Cave 5 N-111, east creekfed passage , Nullarbor Regional Reserve; 29 Nov. 2021; MSLITTER 287; live extract of sediment in desiccating funnel, Matthew Shaw leg. • specimen E 4; Cave 5 N-23 ; female, same data as for holotype .

Mentioned material.

• SAMA J 25680 ; morphotype female; Cave 5 N-111, Nullarbor Regional Reserve, twilight zone, SE passage where stream channel occasionally flows; 30 Nov. 2021 to 9 Mar. 2022; Steve Milner, Andrew Stempel, Matthew Shaw leg., unbaited pitfall trap C • SAMA J 25683 morphotype female, Cave 5 N-22, Nullarbor Wilderness Protected Area, 29 Nov. 2021 to 6 Mar. 2022, S. Milner, A. Stempel, M. D. Shaw leg., Pitfall trap A, sardine-baited, LH wall southside, ca. 40 m from entrance lip, 19.8 degrees, 73 % RH • SAMA J 25684 morphotype female, same data as for preceding • SAMA J 25685 morphotype female, same data as for preceding • SAMA J 25687 Cave 5 N-253, Nullarbor Regional Reserve, M. D. Shaw 2 Dec. 2021, MSLITTER 263, live extraction of cave sediment from desiccating funnel.

Description of larvae.

Dorsum: Length and width of idiosoma 430 (430–508) × 300 (234–300) (n = 4) in these unfed larva. Colour unknown, all larvae colourless when examined after six months in preserving fluids. Dorsal setation 2.4. 6.6. 6.2. The anterolateral borders of the scutum distinct, straight, lateral edges indistinct in holotype J 25686 (Figs 5 View Figures 5, 6 , 6 View Figures 5, 6 ). A slightly concave suture clearly delineates the anterior projecting portion (nasus) from remainder of scutum. This region has a well-rounded convex anterior edge. Anterior region superficially appears as a distinct shieldlet in J 25682. Scutum with mild porosity in posterior half. The longitudinal axis of the scutum features a rod or band of subsurface sclerotization. The edges of this rod appear densely pocked and irregular (Fig. 5 View Figures 5, 6 ). AM setae 40, AL setae 55, PL scutal setae 31. Sensilla long, filiform, mostly nude, bearing sparse array of short cilia in distal quarter. Ocular plate separate to scutum, two eyes, posterior eye smaller.

Gnathosoma: Elongate palp, palp genu approximately twice as long as wide. Minute tibial claw (8) with bifid claw-like tip. Palpal formula (fPp) is B. B. 3 B. 6 BS. Palp tarsus with subterminala, tarsala and 6 long branched setae (ca. 35). Lateral walls of gnathobase with sparse punctations only observed at 1000 ×, medial areas glabrous (Fig. 7 View Figures 7, 8 ). Cheliceral base long, slender, blade barely curved, almost straight (Fig. 8 View Figures 7, 8 ). Galeal setae nude, curved (17).

Venter: No sclerotized plaques or valves around anal opening. Neotrichy absent.

Legs (Figs 9 View Figures 9, 10 – 14 View Figure 14 ): Coxa I and II with coxal setae emerging antero-distally. Coxa III with setae emerging antero-basally. First sternal setae placed laterally at mid-level between coxa I and II. Ventral surface coxae I (Fig. 9 View Figures 9, 10 ) and posterodistad sections of coxa III (Fig. 10 View Figures 9, 10 ) with foveolate ornamentation composed of irregularly-shaped pores. Coxa II with sparse fine pores, no ornamentation.

Leg I: Tr (1 n) – bFe (2 n) – bFe (4 θ, 5 n) – Ge (1 κ, 3 σ, 4 n) – Ti [1 κ, 2 φ, 8 n] – Ta (1 ω, 1 ε, 24 n).

Leg II: Tr (1 n) – Fe (6 θ, 6 n) – Ge (4 σ, 5 n) – Ti (2 φ, 6 n) – Ta (1 ω, 22 n).

Leg III: Tr (1 n) – Fe (5 θ, 6 n) – Ge (3 σ, 5 n) – Ti (1 φ, 6 n) – Ta (23 n).

A famulus (ε, 3 µm) on tarsus I was detected on J 25682 (Fig. 13 View Figures 11–13 ).

Legs terminate in single smooth falcate claws. Claws lack fine hairs (onychtriches) or remnants of these. Claw III is less hooked than anterior claws, curve shallower (Fig. 14 View Figure 14 ).

Description of adults.

Adult female Cruralonga milnerii as per genus diagnosis with following additional features.

Dorsum: Idiosoma without constriction in sejugal plane in mounted specimens (Fig. 15 View Figures 15, 16 ). Dense covering of triradiate setae each borne on a low tubercle. Medial tine of setae subequal in diameter to lateral branches and slightly longer. Each seta inserts in the middle of a faintly-outlined oval-shaped platelet with fine punctations, observable where the dense covering of body setae removed (Fig. 16 View Figures 15, 16 ). Network of threads lying near the surface level of cuticle observed as an irregular mesh-like ornamentation lying between platelets. Crista elongate (Table 2 View Table 2 ), 13 wide. Anterior portion of crista a spade-shaped terminus with three pairs of setae laterally (in C. milnerii type series and all other examined Nullarbor Cruralonga , Fig. 17 View Figures 17, 18 ). Setae on crista are triradiate setae, except anteriormost pair are setulae, lacking lateral branches. Posterior eyes absent. Each anterior eye fused posteriorly with a rugose sclerotized area, considered a modified ocular plate (Fig. 18 View Figures 17, 18 ).

Gnathosoma: Palp claw simple, not bearing accessory setae (Fig. 19 View Figures 19–22 ). Setulae surrounding claw slightly thickened. Palp tarsus longer than claw. Cheliceral base very long; cheliceral blade almost straight, directed forward.

Venter: Length of centrovalves similar to epivalves. Genital region of most specimens not observable due to dense obscuring body setae directed over this area. Epivalves densely covered with setulae with length and thickness matching triradiate body setae but lacking lateral branches. J 25680 shows 7 setulae on each centrovalve (Fig. 20 View Figures 19–22 ). Two pairs of long, narrow oval genital acetabula. Anal valves membranous, each bearing ca. 12 setulae (Fig. 21 View Figures 19–22 ).

Legs: Coxa I to IV with foveolate ornamentation. Anterior internal angle of coxa I strongly modified as an angular anteriorly-directed process (Fig. 22 View Figures 19–22 ). Paired claws smooth, claws reduced on tarsus I. Legs bear setulose setae only. Leg measures in Table 2 View Table 2 .

Etymology.

For Dr Steve Milner whose knowledge, physical efforts and material inputs were vital to access these caves. The epithet is a noun in the genitive case. (Article 11.9.1.3, International Commission of Zoological Nomenclature 1999).

Discussion.

Cruralonga milnerii larvae exhibit distinctive elongate chelicerae and palps. These features were observed in all other Nullarbor Cruralonga too. Three larvae of C. milnerii sp. nov. were recovered from three nearby caves approximately 12 km apart. In two cases, larvae were co-collected with adult Cruralonga specimens indistinguishable from the C. milnerii adult from the type locality. These adults are tentatively identified as morphotype adults of C. milnerii . While conspecificity is suggested here as a preliminary hypothesis to support further investigation, this approach carries significant uncertainty. More data is required to test species limits and requires validation with additional larval specimens or molecular evidence.

Assuming monospecificity of heteromorphic life stages based on co-occurrence can also be problematic. Southcott (1957) reported adults of the epigean N. barringunense and N. neptunium from eucalypt tree trunks at the same locality, and elsewhere noted assuming monospecificity could be “ perilous ” ( Southcott 1954; 1961 p. 502). For related insights, see remarks for Neotrombidium folium sp. nov.

A distinctive sclerotized rod or band lying beneath the scutum, and marking its longitudinal axis, was observed in C. milnerii (Figs 5 View Figures 5, 6 , 6 View Figures 5, 6 ) and is also reported for Monunguis streblida . However, this feature is not reported for Neotrombidium species. Larvae retain the posterior eye as do all other known Neotrombidiidae , however mounted adult Nullarbor Cruralonga lack this.

The tagname “ Neotrombidium YALBB sp 10 ” was used in Shaw (2022) to refer to all Nullarbor cave Neotrombidiidae collected during the Yalata Bush Blitz but is now known to encompass two distinct genera as described herein.