Cryptoplax larvaeformis (Burrow, 1815)

Schwabe, Enrico, Sirenko, Boris I. & Seeto, Johnson, 2008, A checklist of Polyplacophora (Mollusca) from the Fiji islands, Zootaxa 1777, pp. 1-52 : 29-30

Cryptoplax larvaeformis (Burrow, 1815)

( Figures 7 E, F)

Chresonymy in Leloup (1933: 30–32).

Chiton larvaeformis Burrow 1815: 179 , pl. 28, figs 2–4; Gowlett-Holmes 2001: 46; Schwabe 2007: 149.

Cryptoplax larviformis ; de Blainvile 1818: 124.

Chitonellus laevis Lamarck 1819: 317 (syntype MNHN 6017, type locality: “Nouvelle Holland ” [= Australia]); de Blainville 1825: 519; Berge 1847: 113; Fischer 1887: 882; Haddon 1886: 36–38, 41; Lamy 1923: 261; Kaas & Van Belle 1980: 71; 1998: 105; Slieker 2000: 146; Gowlett-Holmes 2001: 46.

Chiton chitonellus Sowerby 1822 : pl. 139, figs 4–5; Kaas & Van Belle 1980: 26.

Chiton eruciformis Sowerby 1822 : pl. 139, fig. 5 [nomen nudum].

Chiton chitonellus de Blainville 1825: 550; Haddon 1886: 37; Kaas & Van Belle 1998: 45; Slieker 2000: 141; Gowlett- Holmes 2001: 46.

Chiton vermiformis de Blainville 1825: 553 (de Blainville wrote, that he saw two specimens in the NHM, but the first author failed in finding them, type locality:? New Holland [= Australia]); Haddon 1886: 37; Pilsbry 1893: 57; Iredale & Hull 1925: 102; Kaas & Van Belle 1980: 139; 1998: 197; Slieker 2000: 154; Gowlett-Holmes 2001: 46.

Chiton fasciatus Quoy & Gaimard 1835 (non Wood, 1815): 408, pl. 73, figs 21–29 (syntype MNHN lost, type locality: Polynesia: Tonga: Ha`apai group [19°48’S 174°21’W]: Pangai-Modou reef); Berge 1847: 113, pl. 20, fig. 6; Kaas & Van Belle 1980: 46; 1998: 71; Slieker 2000: 143; Gowlett-Holmes 2001: 46.

Chitonellus fasciatus ; Reeve 1847: pl. 1, fig. & spec. 2a–b; Dall 1879: 299; van Bemmelen 1882: 95; 1883a: 1; Tryon 1883: 346, pl. 85, fig. 95; Haddon 1886: 36–38, 41, 48; Thiele 1893: 400, pl. 32, fig. 35; Plate 1897: 270; von Martens 1889: 199; Clessin 1904: 124, pl. 38, figs 1–2.

Chiton (Chitonellus) fasciatus ; Chenu 1859: 384, fig. 2891; E. A. Smith 1884: 86.

Chiton (Chitonellus) larvaeformis ; Chenu 1859: 384, fig. 2890; E. A. Smith 1884: 85.

Cryptoplax fasciatus ; Brazier 1877: 75; Fischer 1887: 883.

? Cryptoplax montanoi de Rochebrune 1882: 190 (one syntype MNHN 6066, Philippines: Sulu Islands [05°20’N 120°22’E]); Haddon 1886: 44; Pilsbry 1893: 58; Thiele 1909a: 9, 52; Ashby 1922a: 576, 1923b: 241; Iredale & Hull 1925: 102; Kaas & Van Belle 1980: 87; 1998: 126; Slieker 2000: 148; Gowlett-Holmes 2001: 47; Schwabe 2007: 153.

Cryptoplax peroni de Rochebrune 1882: 193 (holotype MNHN 5985, type locality: “Nouvelle Holland ” [= Australia], based on one of the syntypes of Chitonellus laevis Lamarck, 1819 ); Haddon 1886: 44; Pilsbry 1893: 58; Thiele 1909a: 52, 56; Lamy 1923: 260; Iredale & Hull 1925: 102; Taki & Taki 1930: 105; Kaas & Van Belle 1980: 98; 1998: 142; Slieker 2000: 149; Gowlett-Holmes 2001: 47.

Cryptoplax (Chitonellus) fasciatus ; de Rochebrune 1883: 33.

Chiton (Chitonellus) eruciformis ; E. A. Smith 1884: 86; Haddon 1886: 36.

Chiton (Chitonellus) laevis ; E. A. Smith 1884: 86.

Cryptoplax coronatus de Rochebrune 1884b: 238 (two syntypes at MNHN 6180, type locality: Polynesia: Tonga [19°20’S 174°23’W]); Thiele 1909a: 54; Kaas & Van Belle 1980: 32; 1998: 52; Slieker 2000: 142; Gowlett-Holmes 2001: 47.

Cryptoplax larvaeformis ; Haddon 1886: 37, pl. 3, figs 12a– 12m; Pilsbry 1893–94: 56 (1893), pl. 11, figs 31–36, 40–43 (1894); 1901a: 152, 154, pl. 14, figs 12–16; 1901b: 204; von Martens 1894: 92; Wettstein 1904: 473–504, pls 10–12; Nierstrasz 1905a: 73, pl. 6, figs 154–158; 1905b: 150; Horst & Schepman 1908: 523; Thiele 1909a: 54 (partim); 1931: 15; Iredale & Hull 1925: 101, pl. 12, figs 5, 10, 17, 25, 28, 35; 1927: 91, pl. 11, figs 5, 10, 17, 25, 28, 35; Ashby 1928: 167; Mackay 1930: 295; Taki & Taki 1930: 103; Bergenhayn 1930b: 38, pl. 10, figs 91–93; Leloup 1933: 30; 1940: 25, pl. 3, fig. 1, text fig. 8; 1949: 8, 9, fig. 3C; 1952: 53; Risbec 1946: 130, 134–144, figs 3–6; A. G. Smith 1960: 170, fig 44 1a–f; Kuroda 1960: 1; Fischer-Piette & Franc 1960: 1718, 1738, 1748, 1754, 1756, 1760, 1761, 1764, 1766, fig. 1556A; Ang 1967: 393, 423, pl. 16, figs 1–4; Kaas & Van Belle 1980: 72; 1998: 106; Van Belle 1983: 136, pl. 12, fig. 4; Zeidler & Gowlett 1986: 113; Saito 1994: 144; Littler, Littler & Taylor 1995: 1679; Gowlett-Holmes 2001: 46; Higo et al. 1999: 31; Littler & Littler 1999: 158, text fig; Anonymous 2000: 172, text fig; Slieker 2000: 22, 54, pl. 15, figs 12–12a; Subba Rao & Dey 2000: 5; Wells 2000: 94; Schwabe 2001: 27; 2005a: 54, pl. 2, fig. 11; 2006b: 20; Saito 2001: 23, pl. 11, fig. 3; Xiutong 2004: 4, pl. 2 fig. A; Schwabe & Wanninger 2006: 218, fig. 18.1C; Saito 2006c: 131; Schwabe 2007: 149, figs 3, 4A, C, 5A, C, E, 6A, C.

Chitonellus rostratus (non of Reeve, 1847); Thiele 1893: 400, pl. 32, fig. 38.

Chitonellus larvaeformis ; Pelseneer 1898: 7, 22, 26, pl. 9, fig. 79; Clessin 1904: 123, pl. 40 (not 41 as reported by him), fig. 2.

Cryptoplax lamarcki Thiele 1909 a [nomen nudum, a manuscript name of de Rochebrune, used for the second syntype of Chitonellus laevis Lamarck, 1819 ): 54; Lamy 1923: 261; Kaas & Van Belle 1980: 71; 1998: 105; Gowlett-Holmes 2001: 47.

Cryptoplax laevis ; Dupuis 1918: 529; Ashby 1923b: 239.

Cryptoplax (Chitonellus) larvaeformis ; Ashby 1922a: 576.

Cryptoplax (Chitonellus) laevis ; Ashby 1922a: 577; 1926: 383.

Cryptoplax (Chitonellus) lamarcki ; Ashby 1922a: 577.

Cryptoplax laerviformis [sic]; Bergenhayn 1930b: 54.

Chiton cruciformis ; Kaas & Van Belle 1980: 34; 1998: 56; Slieker 2000: 142; Gowlett-Holmes 2001: 46.

Cryptochiton ; Morton & Raj 1981: 84, pl. IV.8.

Cryptoconchus ; Morton & Raj 1981: 86.

Cryptoconchus [cf.] japonicus ; Morton & Raj 1981: 108, pl. IV.18.

Chiton [sp.]; Abrea 1981: 9, figs 1–3.

Cryptoplax [sp.]; Coleman 1981: 33 (upper picture).

Locus typicus: Unknown.

Primary type: Holotype (NHM 1951.1.28.1).

Fiji records: Cryptochiton ; Morton & Raj 1981: 84, pl. IV.8.

Cryptoconchus ; Morton & Raj 1981: 86.

Cryptoconchus japonicus (...or a related species); Morton & Raj 1981: 108, pl. IV.18.

Cryptoplax larvaeformis ; Haddon 1886: 37, pl. 3, figs 12a–m; Pilsbry 1893: 56, pl. 11, figs 31–34, 40–43; Littler & Littler 1999: 158.

Material examined: USP Mol 2616: 1 adult spm, main Barrier Reef east of Bulia Island [18°50'S 178°35'E], leeward under live coral, USP Kadavu Expedition, leg. J. Browning, 20 July 1970, dry; USP Mol 2660: 1 subadult spm, main Barrier Reef, East of Bulia Island [18°50'S 178°35'E], windward under coral, leg. J. Browning, 17 July 1970, wet; USP Mol 2682 6 adult spms, east of Yaukuve Levu Island [18°48'S 178°31'E], under exposed coral rock, USP Kadavu Expedition, leg. J. Browning 21 July 1970 (on label 1920), wet; ZISP: 2 juvenile spms, Cicia Island [17°45’S 179°18’W], Callisto St. 83, 0.3 m, leg. Boris I. Sirenko, 0 6 February 1975, wet; ZISP: 1 adult spm, Tuvutha Island [17°40’S 178°48’W], Callisto St. 89, 25 m, leg. Boris I. Sirenko, 0 7 February 1975, wet.

Habitat: Morton & Raj (1981) wrote that the species might be found in dead coral limestones in the disused shafts of sipunculids and bivalves. The investigated material shows that the habitat is indeed coral skeletal pieces but the species seems to be actively crawling under them also. Noteworthy is that all specimens were collected close to the fringing reefs of the mentioned localities.

In accordance with the examined material, this shallow water species seemingly has a preference for the underside of coral skeletal fragments lying in fine sand along reef edges.

Distribution: Due to uncertainty in differentiating C. larvaeformis from similar species [e.g., Cryptoplax oculatus (Quoy & Gaimard, 1835) , see Schwabe 2007] the exact distribution pattern of this species remains unclear. In the West it is known from the Andaman Sea (Subba Rao & Dey 2000: 5), in the Northeast from Japan (Saito 2001: 23), in the Southeast from Samoa (Pilsbry 1901: 156), and in the South from New Caledonia (Risbec 1946: 134) and Australia (Gowlett-Holmes 2001: 47).

Remarks: Littler & Littler (1999) pointed out that the species may modify coralline algae structures due to its feeding activities. Flat and two-dimensional crustose coralline algae of the species Porolithon okodes (Heydrich, 1897) alter their form to three-dimensional honeycomb heads when the chitons graze on them.

Recently Saito (2006c: 131) synonymised Cryptoplax dimidiata Ang, 1967 with the present species, but unfortunately he did not explain this decision. The arguments Ang (1967: 427) gave for separating both species seem constant and sufficient to consider both as distinct species. The characters the author pointed out are for instance 1) a different colouration of the girdle spines, and of the articulamentum (deep red in the anterior region in C. dimidiata , while pinkish in the central part of C. larvaeformis ), 2) the different number of valves being in touch (the anterior five in C. dimidiata , compared to four in C. larvaeformis ), 3) a different form of the head valve (oblong with flattened base in C. dimidiata , while subtriangular with rounded corners in C. larvaeformis ), 4) differences in the length of the incisions (not half the length of the tegmentum in C. dimidiata , but almost as long as the tegmentum in C. larvaeformis ), 5) a different orientation of the jugal sinus (diagonal to the surface in C. dimidiata , in C. larvaeformis almost vertical instead). As long as no direct comparisions are possible between the types of both taxa, we do not follow Saito (2006c).

Figures

FIGURE 7. A, Onithochiton societatis Thiele, 1909, ZISP: Fiji, Cicia Island [17 ° 45 ’ S 179 ° 18 ’ W], Callisto St. 83, dorsal view. B – D, Cryptoplax elioti Pilsbry, 1901, dorsal views. B, ZSM Mol 20061619: Fiji, Viti Levu, Laucala Bay, west side of the Nukumbutho channel of the fringing reef opposite the USP, 18 ° 10.899 ' S 178 ° 27.971 ' E. C, ZSM Mol 20061916: Fiji, Viti Levu, Laucala Bay, reef flat opposite the Suva Harbour at the fringing reef, 18 ° 10.434 ' S 178 ° 24.987 ' E, anterior portion. D, same specimen as in fig. C, but posterior portion. E – F, Cryptoplax larvaeformis (de Blainville MS, Burrow, 1815), ZISP: Fiji, Cicia Island [17 ° 45 ’ S 179 ° 18 ’ W], Callisto St. 83. E, dorsal view of the anterior portion. F, dorsal view of the posterior portion. Scale bars 2 mm.