Platevindex coriaceus darwinensis Goulding & Dayrat
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), European Journal of Taxonomy 737 (1), pp. 1-133: 56-60
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|Platevindex coriaceus darwinensis Goulding & Dayrat|
Platevindex coriaceus darwinensis subsp. nov. is named after Darwin, Northern Territory, Australia, which is the type locality.
AUSTRALIA • holotype (28/26  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 GoogleMaps .
AUSTRALIA – Northern Territory • 3 specs (40/25 , 29/21  and 20/14  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 GoogleMaps • 1 spec. (29/16  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 GoogleMaps • 1 spec. (32/17  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 GoogleMaps • 1 spec. (27/19  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 GoogleMaps • 1 spec. (33/25  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 GoogleMaps . Queensland • 1 spec. (31/26  mm); Cairns; 16°52.972′ S, 145°45.665′ E; 15 Jun. 2013; station 98; Rhizophora , Bruguiera and Ceriops , not many dead logs; MTQ GoogleMaps • 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 GoogleMaps • 1 spec. (24/18  mm); Magnetic Island ; 19°10.096′ S, 146°49.366′ E; 23 Jun. 2013; station 106; mostly Avicennia mangrove with mounds of mud; MTQ GoogleMaps • 1 spec. (34/25  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 GoogleMaps • 2 specs (48/34 [no DNA] and 23/17  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 GoogleMaps • 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. GoogleMaps
INDONESIA – Halmahera • 2 specs (36/24  and 28/18  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 GoogleMaps • 4 specs (34/19 , 34/18 , 22/17  and 19/13  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 GoogleMaps .
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 GoogleMaps • 6 specs (from 25/25 to 17/ 15 mm); Kimberley, Cambridge Gulf, Cape Domett ; 14°49.78′ S, 128°23.20′ E; WAM S26581 GoogleMaps • 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 GoogleMaps • 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 GoogleMaps .
Color and morphology of live animals ( Fig. 22 View Fig )
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.
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 View Table 5 ; intestinal loops are of type II, with a transitional loop oriented between 6 and 8 o’clock ( Fig. 17B View Fig ).
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 View Fig ); the retractor muscle varies from the length of the sheath to ¼ of its length.
Distinctive diagnostic features ( Table 4 View 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 View Fig )
Australia: Northern Territory and Queensland. Indonesia: Halmahera.
Habitat ( Fig. 25 View Fig )
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.
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.
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