Platevindex amboinae ( Plate, 1893 ), 2021

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 : 109-115

Platevindex amboinae ( Plate, 1893)

Figs 64–69

Onchidium amboinae Plate, 1893: 177–179 , pl. 7, fig. 8, pl. 11, fig. 66.

Oncis coeca Plate, 1893: 199–200 , pl. 7, fig. 9.

Oncis lata – von Martens 1897: 128 [non Oncis lata Plate, 1893 ].

Oncis coeca – Stantschinsky 1907: 395. — Hoffmann 1928: 86–87.

Oncis amboinae – Hoffmann 1928: 86–87.

Platevindex amboinae – Dayrat 2009: 5.

Material examined

Lectotype (here designated)

INDONESIA • lectotype (28/ 18 mm); Amboina [Ambon]; von Martens leg.; ZMB/Moll 11621a .

Paralectotypes

INDONESIA • 9 paralectotypes (29/20 to 18/ 12 mm); same collection data as for lectotype; ZMB/Moll 11621b .

Holotype of Oncis coeca

INDONESIA • holotype (27/ 16 mm) by monotypy; Amboina [Ambon]; expedition Gazelle leg.; ZMB/Moll 27446 .

Notes on type material Onchidium amboinae . The notum of the lectotype was cut open for the present study to examine the internal anatomy; no internal organs were removed. Three paralectotypes (29/20, 28/21 and 27/ 23 mm) are completely empty with no internal organs. Two paralectotypes (25/17 and 24/ 15 mm) were previously dissected, with their internal organs remaining except for the male parts. Four paralectotypes (24/14, 23/20, 20/15 and 18/ 12 mm) are still unopened.

Oncis coeca . Parts of the posterior (female) reproductive system and of the digestive system are still present in the holotype, although they were previously dissected into pieces, likely by Plate himself. Of the male reproductive parts, only the deferent duct remains.

Other material

INDONESIA – Seram • 1 spec. (38/28 [2883] mm); Piru ; 03°04.072′ S, 128°11.362′ E; 19 Feb. 2014; station 136; beach of palms and Acrostichum ferns behind Sonneratia mangrove; UMIZ 00105 . – Halmahera • 2 specs (32/14 [5043] and 32/22 [5843] mm); Buli; 00°55.367′ N, 128°20.647′ E; 17 Mar. 2015; station 213; tall and old Rhizophora forest, high intertidal; UMIZ 00106 . – Sulawesi • 5 specs (30/25, 20/20, 20/15, 18/15 and 15/ 15 mm); Luwu; M. Weber leg.; ZMB/Moll 46314 • 3 specs (25/20, 22/17 [#1] and 15/ 12 mm); SMF 333602/3 .

Description

Color and morphology of live animals ( Fig. 64 ) Live animals are usually not covered with mud, and their natural color is usually mostly visible without washing. The dorsal notum varies from light brown to dark brown, almost black. The hyponotum varies from grey to dark blue, almost black. The foot is yellowish-grey to dark grey (almost black). Dorsal papillae are short (<1 mm) and do not bear eyes. Large, thorny papillae are absent.

Digestive system ( Figs 3 C–E, 65–66, 67A) Radulae measure up to 5.2 mm long. Examples of radular formulae are presented in Table 5 . The intestinal loops are of type III, with a transitional loop oriented between 1 and 6 o’clock ( Figs 3 C–E, 66A–B). The intestinal loops of the lectotype ( Fig. 67A ) are indistinguishable from those observed in a specimen from Sulawesi ( Fig. 66B ).

Reproductive system ( Figs 67 B–68) In the posterior part of the reproductive system, the oviduct is slightly wider than the deferent duct. Its distal section (distal to the spermatheca) is slightly shorter than its proximal section (or of the same length). The deferent duct is much longer than the oviduct, not attached to it, and highly coiled with long loops. The distal, flexible region of the penis is from 1 to 2.5 mm long and bears no hooks. The posterior retractor muscle of the penis inserts within the anterior half of the visceral cavity (and near the nervous system in specimens from Halmahera). The retractor muscle varies from approximately half the length of the penial sheath to as long as the penial sheath. The deferent duct is highly convoluted, with many loops around the penis. The deferent duct is twice as wide distally as proximally.

Distinctive diagnostic features ( Table 4 )

Externally, the lack of dorsal eyes is shared by both Platevindex amboinae and P. latus . However, the lack of dorsal eyes should be used with caution for identification because dorsal eyes often are retracted (and thus hard to see). Platevindex amboinae can be distinguished from P. latus by the presence of smaller dorsal papillae (the papillae of P. latus are larger and thorny). Internally, intestinal loops of type III are found in only two species of Platevindex , P. amboinae and P. latus . Both species, however, can be distinguished by the deferent duct in the anterior reproductive system, which seems to be slightly more convoluted in P. amboinae than in P. latus , although this should probably be evaluated with additional individuals. Based on the available data, however, P. amboinae and P. latus do not overlap geographically ( Fig. 10 ).

Distribution ( Fig. 10C )

Indonesia: Ambon (type locality of both Platevindex amboinae and P. coecus ), Halmahera (new record) and Seram (new record).

Habitat ( Fig. 69 )

Platevindex amboinae is found on dead logs or tree trunks but not directly on mud, within a mangrove forest or in the higher intertidal adjacent to mangrove trees. It is not found on rocky shores.

Remarks

Onchidium amboinae needs to be transferred to the genus Platevindex due to the following combination of characters of the lectotype: flattened body, male pore slightly to the right of the midline between the ocular tentacles and no accessory penial gland. Plate (1893: 178) also indicated that there is a rectal gland in the original description, and it is clearly present in the lectotype (as in all Platevindex slugs). The absence of dorsal eyes and a short penis with no hooks mentioned by Plate (1893: 177) were confirmed by our examination of the lectotype. The hyponotum color was described as black with a white margin (1 to 1.5 mm wide), which is exactly what was observed in one of our live specimens. However, Plate (1893: 178) described an intestine of type II in Onchidium amboinae , while the intestine of the lectotype (and of all newly-collected individuals) is clearly of type III ( Fig. 67A ).

The holotype of P. coecus (by monotypy) is characterized by a combination of traits diagnostic of species of Platevindex : a flattened body, a male opening slightly to the right of the midline between the ocular tentacles, a rectal gland and no accessory penial gland. In the original description, Plate (1893:199– 200) indicated a grayish-yellow sole and a black-blue hyponotum with a white margin, and also the absence of dorsal eyes. The only species in Ambon which lacks dorsal eyes is P. amboinae . Hoffmann (1928: 86–87) transferred Onchidium amboinae to Oncis (i.e., Platevindex ) and considered Oncis coeca (i.e., Platevindex coecus ) to be a synonym of Oncis amboinae (i.e., Platevindex amboinae ). Labbé (1934: 234–235) agreed with Hoffmann even though he did not examine any new material. The deferent duct in the penial apparatus and in the posterior part of the reproductive system is extremely convoluted, exactly like in P. amboinae . The pieces of the intestine of the holotype were put together and are of type III, although Plate (1893: 200) described a digestive system of type II. There is no anatomical difference between the name-bearing types of Platevindex coecus and P. amboinae , both of which were described from Ambon, Indonesia. We did not find Platevindex amboinae during our mangrove survey in Ambon but we found it on the nearby island of Seram, where it seems to be rare. Platevindex amboinae was also rare in Halmahera. It may still be present in Ambon, but most likely as a rare species.

Two lots previously identified as Oncis lata from Sulawesi are re-identified here as P. amboinae (ZMB/Moll 46314, SMF 333602/3). The original label for ZMB/Moll 46314 indicates that the specimens were collected in Luwu by M. Weber, which means that they are very likely the specimens which von Martens (1897: 128) identified as Oncis lata . Von Martens indicated that he examined 10 specimens. Five of those are in Berlin (ZMB/Moll 46314) and three of them are in Frankfurt-am-Main (SMF 333602/3), which were originally part of the Heidelberg collections. The specimens examined here all lack dorsal eyes, a character shared by both P. lata and P. amboinae , but they also lack the large, thorny papillae that are diagnostic of P. lata , suggesting that they belong to P. amboinae .

Labbé (1934: 234–235) described a specimen (14/ 11 mm) from New Zealand which he identified as Oncis amboinae . However, if Labbé’s description is accurate, this specimen cannot be part of Platevindex amboinae or any species of Platevindex because Labbé (1934: 235) indicated that a group of dorsal eyes was present in the middle of the notum (in Platevindex , dorsal eyes are always single). It is unclear which species Labbé examined, as Onchidella is the only onchidiid genus documented so far in New Zealand. The combination of traits mentioned in the brief description (dorsal eyes, no accessory penial gland and no penial hooks), suggests it could be a Wallaconchis slug, although that is incompatible with intestinal loops of type II. Besides, Wallaconchis is not known south of New Caledonia. Most likely, as often with Labbé’s work, the locality or the description, or even both, are erroneous ( Dayrat et al. 2020).

Figures

Fig. 64. Platevindex amboinae (Plate, 1893), live and preserved animals, Indonesia. A. Dorsal view, 38 mm long [2883], Seram (UMIZ 00105). B. Ventral view, same as A. C. Dorsal view, 32 mm long [5043], Halmahera (UMIZ 00106). D. Ventral view, same as C. E. Dorsal view, preserved specimen, 32 mm long [5843], Halmahera (UMIZ 00106). F. Ventral view, same as E.

Fig. 65. Platevindex amboinae (Plate, 1893), radula, Indonesia, Seram [2883]. A. Rachidian and innermost lateral teeth. B. Lateral teeth with rachidian teeth. C. Lateral teeth. D. Outermost lateral teeth. Abbreviation: lp = lateral protuberance. Scale bars: A, D = 20 μm; B = 30 μm; C = 100 μm.

Fig. 66. Platevindex amboinae (Plate, 1893), digestive system, dorsal view, intestinal loops of type III. A. Transitional loop oriented at 2 o’clock, Seram, Indonesia [2883] (UMIZ 00105). B. Transitional loop oriented at 6 o’clock, Sulawesi, Indonesia [#1] (SMF 333602). Abbreviations: ddg = dorsal digestive gland; i = intestine; pdg = posterior digestive gland; rg = rectal gland; st = stomach. Scale bars: A = 4 mm; B = 3 mm.

Fig. 67. Platevindex amboinae (Plate, 1893), digestive and reproductive systems, lectotype, Ambon, Indonesia (ZMB/Moll 11621a).A. Digestive system, dorsalview, type III,with a transitional loop oriented at 1 o’clock. B. Posterior reproductive system. C. Anterior, male copulatory apparatus. Abbreviations: dd = deferent duct; ddg = dorsal digestive gland; fgm = female gland mass; hd = hermaphroditic duct; hg = hermaphroditic gland; i = intestine; ov = oviduct; pdg = posterior digestive gland; ps = penial sheath; rg = rectal gland; rm = retractor muscle; rs = receptaculum seminis; sp = spermatheca; st = stomach; v = vestibule. Scale bars: A = 4 mm; B = 3 mm; C = 2 mm.

Fig. 68. Platevindex amboinae (Plate, 1893), reproductive system, Seram, Indonesia [2883] (UMIZ 00105). A. Posterior reproductive system. B. Anterior, male copulatory apparatus. Abbreviations: dd = deferent duct; fgm = female gland mass; hd = hermaphroditic duct; hg = hermaphroditic gland; ov = oviduct; ps = penial sheath; rm = retractor muscle; rs = receptaculum seminis; sp = spermatheca; v = vestibule. Scale bars: A = 4 mm; B = 2 mm.

Fig. 69. Habitats of Platevindex amboinae (Plate, 1893), Indonesia.A. Halmahera, open, tall Rhizophora forest, impacted by mining (station 213). B. Seram, on base of palm tree surrounded by Acrostichum ferns behind a Sonneratia mangrove (station 136).

Fig. 3. Intestinal loops of type III. Small black arrows show the direction of the intestinal transport. The clockwise loop is in blue. The counterclockwise loop is in yellow. The transitional loop (between clockwise and counterclockwise loops) is in green. Red arrows indicate the orientation of the transitional loop. A. Type III, with a transitional loop oriented at 3 o’clock, Onchidium stuxbergi (Westerlund, 1883) (from Dayrat et al. 2016: fig. 11b). B. Type III, with a transitional loop oriented at 12 o’clock, Platevindex latus (Plate, 1893) (ZMH 27511, #1), Papua New Guinea. C. Type III, with a transitional loop oriented at 1 o’clock,P. amboinae (Plate, 1893), lectotype (ZMB/Moll 11621a), Ambon, Indonesia. D. Type III, with a transitional loop oriented at 2 o’clock, P. amboinae [2883] (UMIZ 00105), Seram, Indonesia. E. Type III, with a transitional loop oriented at 6 o’clock, P. amboinae (SMF 333602, #1), Sulawesi, Indonesia. Scale bars: A–B = 5 mm; C–E = 4 mm.

Fig. 10. Geographic distributions of species of Platevindex. Colored areas correspond to hypothetical ranges proposed based on all known records, and the colors are the same as those used for each species in the phylogenetic trees (Figs 1–5). Distinct colors are used for each subspecies and mitochondrial unit in P. coriaceus (Semper, 1880) as well as for each subspecies of P. burnupi (Collinge, 1902). Black dots show sites sampled for this study and red dots (China and Japan) show localities of previously published genetic sequences included in the phylogenetic analyses. A. Platevindex luteus (Semper, 1880), P. applanatus (Simroth, 1920), P. burnupi. B. Platevindex tigrinus (Stoliczka, 1869), P. coriaceus coriaceus (units #1, #2, and #3) and P. coriaceus darwinensis subsp. nov. C. Platevindex martensi (Plate, 1893), P. aptei Goulding & Dayrat sp. nov., P. amboinae (Plate, 1893) and P. latus (Plate, 1893).