Platevindex coriaceus subsp. darwinensis Goulding & Bourke & Comendador & Khalil & Quang & Tan & Tan & Dayrat 2021, subsp. nov.
Creators: name: Goulding, Tricia C.
name: Bourke, Adam J.
name: Comendador, Joseph
name: Khalil, Munawar
name: Quang, Ngo Xuan
name: Tan, Shau Hwai
name: Tan, Siong Kiat
name: Dayrat, Benoît
Publisher: name: Zenodo
Year: 2021
Subjects: Biodiversity
Taxonomy
Animalia
Mollusca
Gastropoda
Systellommatophora
Onchidiidae
Platevindex
Platevindex coriaceus
Platevindex coriaceus darwinensis goulding &amp; dayrat

description: Platevindex coriaceus darwinensis Goulding & Dayrat subsp. nov.
urn:lsid:zoobank.org:act: A609EB85-101E-467E-AFD5-812043EDAFFE
Figs 16B, 18D, 19D, 22–25
Etymology
Platevindex coriaceus darwinensis subsp. nov. is named after Darwin, Northern Territory, Australia, which is the type locality.
Material examined
Type material
AUSTRALIA • holotype (28/26 [1700] mm); Northern Territory, Darwin, close to Tiger Brenan Rd; 12°28.782′ S, 130°54.750′ E; 19 Aug. 2012; station 69; high tidal Ceriops mangrove by small service road; NTM P.57601.
Other material
AUSTRALIA – Northern Territory • 3 specs (40/25 [1674], 29/21 [1663] and 20/14 [1672] mm); Darwin, Talc Head; 12°28.765′ S, 130°46.297′ E; 15 Aug. 2012; station 62; open forest of large Sonneratia alba with mud saturated with water; NTM P.57602 • 1 spec. (29/16 [1677] mm); Darwin, Near Berrimah; 12°28.786′ S, 130°54.750′ E; 16 Aug. 2012; station 63; Sonneratia, Rhizophora and Ceriops mangrove forest; NTM P.57603 • 1 spec. (32/17 [1633] mm); Darwin, near Channel Island Rd; 12°33.557′ S, 130°52.889′ E; 16 Aug. 2012; station 64; Sonneratia, Rhizophora and Ceriops mangrove forest; NTM P.57604 • 1 spec. (27/19 [1690] mm); Darwin, end of Channel Island Rd; 12°33.557′ S, 130°52.894′ E; 17 Aug. 2012; station 66; Sonneratia, Rhizophora and Ceriops mangrove forest; NTM P.57606 • 1 spec. (33/25 [1701] mm); Darwin, close to Tiger Brenan Rd; 12°28.782′ S, 130°54.750′ E; 19 Aug. 2012; station 69; high tidal Ceriops mangrove by small service road; NTM P.57608. Queensland • 1 spec. (31/26 [2549] mm); Cairns; 16°52.972′ S, 145°45.665′ E; 15 Jun. 2013; station 98; Rhizophora, Bruguiera and Ceriops, not many dead logs; MTQ • 1 spec. (50/27 [no DNA] mm); Flying Fish Point; 17°30.001′ S, 146°04.295′ E; 20 Jun. 2013; station 104; mangrove by creek with sandy mud; MTQ • 1 spec. (24/18 [2590] mm); Magnetic Island; 19°10.096′ S, 146°49.366′ E; 23 Jun. 2013; station 106; mostly Avicennia mangrove with mounds of mud; MTQ • 1 spec. (34/25 [2679] mm); Campwin Beach; 21°22.455′ S, 149°18.753′ E; 5 Jul. 2013; station 121; narrow Rhizophora mangrove with watery mud and large rocks by creek; MTQ • 2 specs (48/34 [no DNA] and 23/17 [2689] mm); Armstrong Beach; 21°27.129′ S, 149°17.084′ E; 6 Jul. 2013; station 123; margin of Rhizophora and Avicennia mangrove with open mudflat; MTQ • 1 spec. (48/29 [no DNA] mm); Queensland, Pioneer River; 21°08.511′ S, 149°12.076′ E; 8 Jul. 2013; station 125; Avicennia & Rhizophora mangrove; MTQ.
INDONESIA – Halmahera • 2 specs (36/24 [5071] and 28/18 [5021] mm); Dodinga; 00°51.348′ N, 127°38.504′ E; 9 Mar. 2015; station 206; high intertidal back of mangrove with Acrostichum sp. and mounds of mud; UMIZ 00080 • 4 specs (34/19 [5112], 34/18 [5109], 22/17 [5111] and 19/13 [5110] mm); Buli; 00°55.446′ N, 128°20.612′ E; 16 Mar. 2015; station 212; logged area in front of old Rhizophora forest; UMIZ 00081.
Other museum material without DNA sequences
AUSTRALIA – Western Australia • 13 specs (from 35/30 to 20/20 mm); Kimberley, Whirlpool Pass; 16°15. 81′ S, 123°29.88′ E; on mangroves; WAM S42812 • 6 specs (from 25/25 to 17/15 mm); Kimberley, Cambridge Gulf, Cape Domett; 14°49.78′ S, 128°23.20′ E; WAM S26581 • 4 specs (from 35/30 to 15/15 mm); Exmouth Gulf, Tubridgi Point Boat Channel; 21°50.0′ S, 114°39.90′ E; WAM S26772 • 5 specs (from 30/30 to 8/8 mm); Exmouth Gulf, NE of Tent Point; 22°00.0′ S, 114°30.5′ E to 22°00.4′ S, 114°32.1′ E; WAM S26777.
Description
Color and morphology of live animals (Fig. 22)
Identical to P. coriaceus coriaceus (see above), acknowledging some minor variations: the hyponotum is grey or light grey; the foot is light yellow; there are between 20 and 36 papillae with dorsal eyes, the largest animals bearing the largest numbers of eyes.
Digestive system (Figs 17B, 23)
Identical to that of P. coriaceus coriaceus (see above), acknowledging some minor variations: radulae measure up to 7.4 mm; examples of radular formulae are presented in Table 5; intestinal loops are of type II, with a transitional loop oriented between 6 and 8 o’clock (Fig. 17B).
Reproductive system (Figs 18–19, 24)
Identical to that of P. coriaceus coriaceus (see above), acknowledging some minor variations: the distal section of the oviduct (i.e., distal to the spermatheca) is long, up to two times the length of the proximal section (from the female gland mass to the spermatheca); the oviduct is much wider (up to five times) than the deferent duct; penial hooks measure from 60 to 110 μm; the flexible region of the penis with hooks is between 2 and 8 mm long (Fig. 24); the retractor muscle varies from the length of the sheath to ¼ of its length.
Distinctive diagnostic features (Table 4)
Platevindex coriaceus coriaceus and P. coriaceus darwinensis subsp. nov. are indistinguishable externally.The only minor difference in color variation is that a dark blue-grey hyponotum was observed in P. coriaceus coriaceus (most commonly in the Philippines) but never in P. coriaceus darwinensis subsp. nov. Internally, both subspecies can hardly be distinguished either. The ratio between the oviduct width and the deferent duct width tends to be much higher in P. coriaceus darwinensis subsp. nov. than in P. coriaceus coriaceus, but a higher variation may be discovered in the future. However, based on current data, P. coriaceus coriaceus and P. coriaceus darwinensis subsp. nov. do not overlap geographically.
Distribution (Fig. 10B)
Australia: Northern Territory and Queensland. Indonesia: Halmahera.
Habitat (Fig. 25)
Platevindex coriaceus darwinensis subsp. nov. is found in the same habitat as the nominotypical subspecies, i.e., mangrove forests, on tree roots, tree trunks and logs. It is very common in the Northern Territory (Australia) and Halmahera (Indonesia). It seems to be less common in Queensland (Australia), with Platevindex luteus found in higher abundance.
Remarks
A new subspecific name is needed because no existing species-group name could apply with confidence to the taxon recognized here. Platevindex cinereus was described from Broome, Western Australia, by Odhner (1917) as Oncis cinerea, exclusively known from the holotype, by monotypy, which is a small (9/ 9 mm) and immature specimen (SMNH 945). There is no doubt that the holotype of Oncis cinerea belongs to a species of Platevindex, but, because it is immature, it is not possible to determine which one. Platevindex cinereus could apply to either of the two species sampled in the Northern Territory, Australia, P. coriaceus darwinensis subsp. nov. or P. martensi, and even to the widespread species P. luteus, although the latter has not been recorded from Northern Territory or Western Australia. Because it will remain impossible to confidently apply P. cinereus to any particular species of Platevindex, it is regarded here as a nomen dubium. Some onchidiid slugs from the collections of the Western Australia Museum are identified here as P. coriaceus based on the position of their dorsal eyes and their reproductive anatomy. Whether populations of P. coriaceus from Western Australia belong to P. coriaceus coriaceus, P. coriaceus darwinensis subsp. nov., or even a distinct subspecies would have to be checked with fresh material from Western Australia.
Bretnall’s (1919: 323) description of Onchidium coriaceum from Queensland does not appear to be based on Platevindex slugs: “short conical papillae” and a hyponotum “regularly yellowish” are not compatible with P. coriaceus darwinensis subsp. nov.
description: Published as part of Goulding, Tricia C., Bourke, Adam J., Comendador, Joseph, Khalil, Munawar, Quang, Ngo Xuan, Tan, Shau Hwai, Tan, Siong Kiat & Dayrat, Benoît, 2021, Systematic revision of Platevindex Baker, 1938 (Gastropoda: Euthyneura: Onchidiidae), pp. 1-133 in European Journal of Taxonomy 737 (1) on pages 56-60, DOI: 10.5852/ejt.2021.737.1259, http://zenodo.org/record/4594357