Chordaropa garethseetoi, Stanisic & Holcroft, 2025

Stanisic, John Stanisic Lorelle & Holcroft, formerly, 2025, Two new species of Chordaropa Stanisic, 2016 from differing bushland habitats in Brisbane City, south-east Queensland (Gastropoda: Eupulmonata: Charopidae), Memoirs of the Queensland Museum | Nature 66, pp. 63-72 : 66-69

Chordaropa garethseetoi sp. nov. ( Figs 1, 2A, 4A–B)

Material examined: Holotype: QMMO76854 , 1 RC, Brisbane City , Bulimba Creek , SEQ (27°30´09'' S, 153°06´34'' E), Forest Red Gum association on river flats, under logs. Coll. QM Party, 22.iv.2003. Height of shell 2.76 mm, diameter 5.16 mm, width of umbilicus 1.23 mm, D/U 4.20, H/D 0.54, whorls 4.75.

Other material: QMMO76883 , 1 RC, Brisbane City , Ransome Bushland Reserve, SEQ (27°29´34'' S, 153°11´05'' E), Casuarina ecotone, under logs. Coll . QM Party, 10.ii.2003 .

Diagnosis: Shell tiny, diameter 5.16 mm; protoconch sculptured with 18–20 low, broad spiral cords; teleoconch with 57–59 (mean 58) radial ribs on first whorl, 103–119 on fourth whorl, umbilicus wide U-shaped, diameter 1.23 mm.

Description: Shell tiny, brown, discoidal with a flat to slightly sunken spire; whorls 4.75, tightly coiled, shouldered above and rounded below the periphery, last slowly descending in front; sutures strongly impressed. Diameter of shell 5.16 mm, height 2.79 mm, H/D 0.54. Protoconch 1.5 whorls, diameter 490 µm, pitted cancellate sculptured with low, broad spiral cords and weak, curved radial ridges that become increasingly prominent toward the protoconch-teleoconch boundary; teleoconch with very crowded, protractively sinuate radial ribs, 57–59 (mean 58) on first adult whorl, 103–119 (mean 111) on fourth whorl, microsculpture of numerous very fine radial riblets, approximately 5–7 between each pair of major ribs, and low spiral cords forming elongate beads at their intersection. Aperture ovately lunate, lip simple. Umbilicus wide U-shaped,diameter 1.23 mm, D/U 4.20. Reproductive anatomy unknown.

Distribution and habitat: Known from Bulimba Creek Reserve and Ransome Bushland Reserve, Brisbane, SEQ; collected among litter in disturbed riparian vegetation comprising Forest Red Gums with understorey rainforest elements, and moist eucalypt bushland encompassing a Casuarina ecotone.

Remarks: Chordaropa garethseetoi sp. nov. differs from C. myora (Stanisic, 2010) by having looser coiling, a less sunken spire and fewer crowded radial ribs on the first and fourth teleoconch whorls. In comparison, C. oxleyana sp. nov. has a smaller shell with a greater number of ribs on both the first and fourth teleoconch whorls.

Riparian habitats are not considered the primary habitat for any eastern Australian land snail.However, they are important dispersal corridors from a snail’s core habitat. The discovery of C. garethseetoi along Bulimba Creek may indicate dispersal from the nearby Belmont Hills Bushland Reserve that contains the headwaters of Bulimba Creek. This site was surveyed as part of the Brisbane City survey and protects several vegetation communities including rainforest. Many pinwheel snails were located at the Belmont Hills site but not Chordaropa spp. Additional survey work may determine whether C. garethseetoi occurs in the reserve.

Etymology: Named for Gareth Seeto, a member of the Rotaract Club of Paddington who won the naming rights in a fundraising raffle for voluntary work on a Rotary project in the Solomon Islands.

Preferred common name: Gareth Seeto’s Pinwheel Snail.

Chordaropa oxleyana sp. nov. ( Figs 1, 2B, 3A, 4C–D)

Material examined: Holotype: QMMO86973 , 1 RC, Fort Road Reserve , Oxley, SEQ (27°33´00'' S, 152°57´50'' E), gully rainforest with Araucaria , under logs and rocks. Coll. J. Stanisic, L. Holcroft, 22.vii.2019. Height of shell 2.58 mm, diameter 4.18 mm, width of umbilicus 1.23 mm, D/U 3.40, H/D 0.57, whorls 4.25.

Paratype: QMMO86091 , 1 RC, subadult, same data as holotype .

Other material: QMMO87867 , 6 RC, Three Mile Scrub , Enoggera Creek , Newmarket, Brisbane, SEQ (27.430896° S, 152.99701° E), rainforest with Araucaria , under logs. Coll. C.J. Wild , c. 1900.

Diagnosis: Shell tiny, diameter 4.10–4.51 mm; protoconch sculptured with 18–20 low, broad spiral cords; teleoconch with 67–83 radial ribs on first whorl, 113–132 on fourth whorl; umbilicus wide U-shaped, diameter 1.22 mm.

Description: Shell tiny, brown, discoidal with a flat to slightly sunken spire; whorls 4.0–4.5 (mean 4.25), tightly coiled, shouldered above and rounded below the periphery, last slowly descending in front; sutures strongly impressed. Diameter of shell 4.10–4.51 (mean 4.26) mm, height 2.21–2.62 (mean 2.40) mm, H/D 0.53–0.60 (mean 0.56). Protoconch 1.5 whorls, diameter 490 µm, pitted cancellate sculptured with low, broad spiral cords and sinuate radial ridges that become increasingly prominent toward the protoconch-teleoconch boundary; teleoconch with very crowded, protractively sinuate radial ribs, 67–83 (mean 71) on first adult whorl, 113–132 (mean 122) on fourth whorl, microsculpture of numerous very fine radial riblets, approximately 5–7 between each pair of major ribs, and low spiral cords forming elongate beads at their intersection. Aperture ovately lunate, lip simple. Umbilicus wide U-shaped, diameter 1.15–1.39 (mean 1.22) mm, D/U 3.24–3.79 (mean 3.52). Based on six measured adult shells (QMMO86091, QMMO86973, QMMO87867). Reproductive anatomy unknown.

Distribution and habitat: Known from the Fort Road Reserve, Oxley and historically from the now cleared Three Mile Scrub, Newmarket, Brisbane, SEQ; living under logs in rainforest with araucarian emergents.

Remarks: Chordaropa oxleyana sp. nov. has a smaller shell than C. garethseetoi sp. nov. with a greater number of ribs on both the first and fourth teleoconch whorls. The shell of C. oxleyana is also smaller than that of C. myora , which has more tightly coiled whorls and more numerous ribs on the fourth teleoconch whorl.

The habitat at Fort Road Reserve preserves a remnant of the araucarian notophyll vine forest that was once commonplace along the Brisbane River and some of its tributaries. Most of this rainforest type has been cleared in the lowland areas of Greater Brisbane but is still largely preserved in the uplands of the D’Aguilar National Park (Mt Nebo, Mt Glorious).

Chordaropa oxleyana was previously also known to occur in the Three Mile Scrub, Enoggera Creek, Newmarket, SEQ and was collected from the site by Queensland Museum collector C.J. Wild around 1900, though an exact date is not known. This area of lush rainforest, characterised by tall hoop pines ( Araucaria cunninghamii ), has disappeared through early timber harvesting and subsequent development of the Newmarket/Enoggera Creek area. The Banks Street Reserve preserves some examples of the original trees. However, it is unlikely that the Oxley Pinwheel Snail survives in the area.

Etymology: Named for the locality of Oxley, Brisbane City.

Preferred common name: Oxley Pinwheel Snail.