Semper, 1880 : 262 Semper, 1880 : 268 Simroth, 1918 : 294 Britton, 1984 : 188 Onchidium samarense – Semper 1882: 268–269 A new genus and three new species of mangrove slugs from the Indo-West Pacific (Mollusca: Gastropoda: Euthyneura: Onchidiidae) Dayrat, Benoît Goulding, Tricia C. Khalil, Munawar Apte, Deepak Bourke, Adam J. Comendador, Joseph Tan, Shau Hwai European Journal of Taxonomy 2019 2019-02-22 500 1 77 4DRDV (Semper, 1880) Dayrat & Goulding & Khalil & Apte & Bourke & Comendador & Tan 2019 Semper 1880 [486,964,267,294] Gastropoda Onchidiidae Paromoionchis Animalia Systellommatophora 21 22 Mollusca species tumidus comb. nov.    Figs 7–25     Onchidium tumidum  Semper, 1880: 262–263, pl. 20, figs 3–4, pl. 23, fig. 4.    Onchidium samarense  Semper, 1880: 268–269, pl. 20, figs 9, 13, pl. 23, fig. 7. Syn. nov.    Onchidium mertoni  Simroth, 1918: 294–296, pl. XX, figs 43–47. Syn. nov.    Onchidium hongkongense  Britton, 1984: 188–190, figs 6–7. Syn. nov.    Onchidium samarense– Semper 1882: 268–269, pl. 21, fig. 5.    Material examined  Type material  SINGAPORE• lectotype(here designated; 28/ 22 mm); ZMB39019a•  15 paralectotypes; ZMB 39019b•  2 paralectotypes; NHMD 300305•  1 paralectotype; SMF 333603/1.   AUSTRALIA• 2 paralectotypes; Queensland, Mackay; ZMB39020.  Other type material   PHILIPPINES• lectotypeof  Onchidium samarense(here designated; 22/ 17 mm); Samar Island, Palapaharbor; ZMB39025a•  2 paralectotypesof  O. samarense(24/20 and 20/ 15 mm); same locality as lectotype; ZMB39025b.   INDONESIA• lectotypeof  Onchidium mertoni(here designated; 15/ 9 mm); Aru Islands, Kobroor, Sungai;  5 Jan. 1908; ZMB 121591a•  4 paralectotypesof  O. mertoni(  14/8, 14/10, 15/14 and 14/ 10mm); same data as for lectotype; ZMB 121591b.   CHINA• holotypeof  Onchidium hongkongense(17/ 13 mm); Hong Kong; NHM 1982290•  15 paratypes; same locality as holotype; NHM 1982291to 1982292.   Notes on typematerial   Onchidium tumidum. Lectotype, 28/ 22 mm, designated here (ZMB 39019a). Allother syntypesbecome paralectotypes(the 15 paralectotypesfrom the same lot are now ZMB 39019b).  Accordingto the original description, the type material included 42 specimensfrom Singaporeand an unknown number of specimens from  Port Mackay, Queensland, Australia. A total of 21 syntypeswere located in museum collections: 19 specimensfrom Singapore( 16 specimens, ZMB 39019; 2 specimens, NHMD 300305; 1 specimen, SMF 333603/1) and 2 specimensfrom Mackay(ZMB 39020). Therealso are two possible syntypesfrom Australia(ZMH 27480/2). Twosimilar species of  Paromoionchis gen. nov.are found at Port Mackay,  P. tumidusand  P. daemelii, which anatomically can only be distinguished based on the insertion of the retractor muscle of the penis. Inthe lectotypedesignated here from Singapore, the retractor muscle inserts near the heart, exactly as in the species described here. However, in one of the two paralectotypesof  P. tumidusfrom Mackay(ZMB 39020), the retractor muscle is vestigial, as in  P. daemelii(in the other paralectotypefrom Mackay, the male apparatus was destroyed prior to the present investigation and could not be examined). Hence, it was necessary to designate a lectotypefrom Singaporein order to clarify the application of  P. tumidus. Notethat the type material was fixed in formalin more than 130 years ago and no DNA sequencing could be attempted.   Onchidium samarense. Lectotype, 22/ 17 mm, designated here (ZMB 39025a). Thetwo other syntypesbecome paralectotypes(ZMB 39025b). Accordingto the original description, the type material included only two specimens from the same locality in Samar, Philippines. However, the jar with the type material currently contains three similar-looking specimens ( syntypes), all of which were dissected prior to the present study. Itis not excluded that the original description was based on only two of those three specimens but it is also possible that Semperhimself identified all three specimens as  O. samerense[sic] (with a minor typo in the original description). The lectotypestill contains all its internal organs, including the male copulatory parts. One paralectotype(24/ 20 mm) is mostly destroyed, with no internal organs left except the digestive gland (a few destroyed pieces of organs are in a vial). Theother paralectotype(20/ 15 mm) still contains internal organs, but the male parts are missing. Ourobservations and comments are mostly based on the only specimen with male parts; hence its designation as a lectotype. Notethat the type material was fixed in formalin more than 130 years ago and no DNA sequencing could be attempted. Note also that if, in the future,  Onchidium samarensewere to be regarded as a valid species name in  Paromoionchis gen. nov., the specific name  samarense(neuter) would need to become samarensis(masculine).   Onchidium mertoni. Lectotype, 15/ 9 mm, designated here (ZMB 121591a). The four other syntypesbecome paralectotypes(ZMB 121591b). Simroth mentioned in the original description that all five specimens were very hard. Indeed, it seems that they dried out at some point and they are very poorly preserved. The lectotypedesignated here is the only specimen that is complete. It was partially dissected for the present study (the penial hooks, identical to those of  O. tumidum, are illustrated here). Two paralectotypes( 14/8 and 14/ 10mm) were dissected prior to the present study and are completely empty. Two other paralectotypes( 15/14 and 14/ 10mm) are in very poor condition (the body is extremely hard and the digestive system is partly outside the body through the foot). A lectotypeis designated here to clarify the application of the name  O. mertonibecause several species of  Paromoionchis gen. nov.are potentially sympatric in the Aru Islands and so it cannot be excluded that the five original syntypesbelong to different species. Note that the type material was fixed in formalin more than 100 years ago and no DNA sequencing could be attempted.   Onchidium hongkongense. Holotype, 17/ 13 mm, by original designation (NHM 1982290) and 15 paratypes(NHM 1982291, NHM 1982292). The holotypeis largely destroyed due to prior dissection, likely by Britton. Large parts of the notum and of the reproductive organs are missing. Even though it is mostly destroyed, the digestive system is confirmed to be of type II. A few paratypeswere checked for the present study and their anatomy matches that of the holotype. Note that the type material was fixed in formalin more than 40 years ago and no DNA sequencing could be attempted. Note also that the specific name hongkongensis(masculine or feminine gender) originally used by Britton is corrected to  hongkongense(neuter) for gender agreement with  Onchidium. Should  Onchidium hongkongenseever become a valid species name in  Paromoionchis gen. nov.,  hongkongensewould then need to be changed back to hongkongensis.   Other material   AUSTRALIA–  New South Wales• 1 spec. (20/15 [1522] mm); Sydney, Pittwater, Careel Bay; 33°37.323´S, 151°19.878´E;  24 Nov. 2011; station 40; supratidal zone on margin of salt marsh, mangrove patch on side of creek; AM C.468918.005• 1 spec. (35/20 [1529] mm); Sydney, Hawkesbury River, Cheero Point; 33°30.687´S, 151°11.669´E;  25 Nov. 2011; station 42; open mangrove with old logs; AM C.468924.001• 1 spec. (33/20 [1528] mm); same data as for preceding; AM C.468923.002• 1 spec. (32/20 [1530] mm); same data as for preceding; AM C.468925.001. –   Northern Territory• 1 spec. (45/32 [1634] mm); Darwin, near Channel IslandRoad; 12°34.979´S, 130°55.992´E;  16 Aug. 2012; station 65; sequence of  Sonneratia,  Rhizophoraand  Ceriops; NTM P.57620• 1 spec. (40/25 [1686] mm); Darwin, end of Channel IslandRoad; 12°33.557´S, 130°52.894´E;  17 Aug. 2012; station 66; sequence of  Sonneratia,  Rhizophoraand  Ceriops; NTM P.57621• 1 spec. (42/38 [1638] mm); same data as for preceding; NTM P.57623• 2 spec. (30/17 [1705] and 17/12 [1645] mm); Darwin, close to Tiger Brenan Road(small service road); 12°28.782´S, 130°54.750´E;  19 Aug. 2012; station 69; high tidal  Ceriops; NTM P.57622• 1 spec. (36/22 [1651] mm); Darwin, Elizabeth Road; 12°32.893´S, 130°57.642´E;  20 Aug. 2012; station 70;  Ceriopsand old logs in  Rhizophoraforest; NTM P.57624. –   Queensland• 1 spec. (45/30 [2562] mm); Cairns, Yorkey’s Knob; 16°48.558´S, 145°42.768´E;  17 Jun. 2013; station 101; hard, red mud with grasses; MTQ• 1 spec. (45/30 [2602] mm); Townsville, Magnetic Island; 19°09.938´S, 146°49.029´E;  24 Jun. 2013; station 109; water on the mud; MTQ• 1 spec. (15/10 [2627] mm); Bowen; 20°00.658´S, 148°15.878´E;  1 Jul. 2013; station 115; back of mangrove across from beach, dense  Rhizophora,  Avicenniatrees with soft mud around; MTQ• 1 spec. (55/30 [2637] mm); Bowen; 20°00.913´S, 148°15.745´E;  1 Jul. 2013; station 116; mangrove away from ocean, small area of open  Avicenniamangrove, surrounded by  Rhizophora; MTQ• 1 spec. (20/10 [2652] mm); Bowen, Doughty Creek; 20°01.264´S, 148°14.345´E;  2 Jul. 2013; station 117; narrow  Avicenniaand  Rhizophoramangrove, by creek, some muddy areas and some very sandy; MTQ• 1 spec. (35/20 [2657] mm); Bowen; 20°01.478´S, 148°14.224´E;  3 Jul. 2013; station 119;  Rhizophoraand  Avicenniamangrove; MTQ• 1 spec. (30/20 [2701] mm); Mackay; 20°08.511´S, 149°12.076´E;  8 Jul. 2013; station 125; large, dense and sandy mangrove and, by side of river, small strip of mud with  Avicenniaand  Rhizophora; MTQ• 1 spec. (30/25 [1531] mm); Thirsty Sound, Plum Tree, beach in front of Endeavour Park; 22°08.144´S, 150°01.856´E;  14 Sep. 2002; I. Loch, D.L.Beechey and A.C. Millerleg.; sheltered, muddy cobble shore; AM C.575588.   BRUNEI DARUSSALAM• 3 spec. (55/30 [1036], 35/20 [1035] and 20/15 [1062] mm); Pulau Pyatan, Teluk Brunei; 04°55.246´N, 115°02.764´E;  27 Jul. 2011; station 32; open  Avicenniaand  Rhizophoramangrove, with hard mud; BDMNH.   INDIA• 1 spec. (26/17 [1119] mm); Andaman Islands, Middle Andaman, Shantipur, Kadamtala; 12°19.843´N, 092°46.377´E;  12 Jan. 2011; station 58; open area with hard mud and many old logs, next to a mangrove with medium trees; BNHS 88.   INDONESIA–  Sumatra• 1 spec. (24/15 [1732] mm); Kualapenet; 05°16.275´S, 105°51.287´E;  17 Oct. 2012; station 77; narrow band of mangrove between ocean and fish ponds; UMIZ 0 0 121• 2 spec. (35/20 [1754] and 26/16 [1755] mm); Bakauheni; 05°50.560´S, 105°46.200´E;  21 Oct. 2012; station 81; small mangrove, not far from road and next to large harbor, very impacted mangrove; UMIZ 0 0 122• 1 spec. (38/30 [1794] mm); same data as for preceding; UMIZ 0 0 138• 1 spec. (20/12 [1798] mm); S of Bandar Lampung; 05°32.66´S, 105°15.113´E;  28 Oct. 2012; station 83; high intertidal, fairly dense roots with some  Avicenniaand  Nypa, edge of mangrove by road; UMIZ 0 0 123. –   Sulawesi• 2 spec. (25/15 [2200] and 20/12 [2201] mm); Tamperong; 01°41.513´N, 125°00.797´E;  12 Mar. 2013; station 87; muddy mangrove with small  Rhizophorain dense patches; UMIZ 0 0 124• 1 spec. (27/15 [2240] mm); Sondaken; 01°21.777´N, 124°32.594´E;  13 Mar. 2013; station 89; sand, small rocks, pieces of wood outside narrow coastal mangrove of mostly  Rhizophora; UMIZ 0 0 125• 1 spec. (30/20 [2345] mm); Makassar, Tallomangrove; 05°06.117´S, 119°26.777´E;  21 Mar. 2013; station 92; small mangrove used as outhouse by village, very impacted with trash; UMIZ 0 0 126•  1spec. (20/13 [2355] mm); Barru; 04°25.437´S, 119°35.953´E;  22 Mar. 2013; station 93; forest of mostly  Avicenniaand  Rhizophora, with hard and sandy mud; UMIZ 0 0 127. –  Ambon• 1spec. (25/15 [3541] mm); Lateri; 03°38.261´S, 128°14.716´E;  12 Feb. 2014; station 128; mudflat next to small creek in low intertidal of mangrove preserve; UMIZ 0 0 128• 3 spec. (45/30 [2832], 22/12 [2839] and 35/22 [2840] mm); Lateri; 03°38.237´S, 128°14.783´E;  14 Feb. 2014; station 131; muddy mangrove with  Rhizophora; UMIZ 0 0 129. –  Seram• 2spec. (20/15 [2874] and 30/15 [2875] mm); Kawa; 02°58.240´S, 128°07.066´E;  18 Feb. 2014; station 135; mud next to a seawall adjacent to a mangrove; UMIZ 0 0 130. –  Lombok• 2spec. (30/20 [2950] and 20/12 [2952] mm); Tanjung Batu village; 08°45.748´S, 116°02.892´E;  24 Mar. 2014; station 145;   Avicenniaforest; UMIZ 0 0 131• 1 spec. (20/14 [2961] mm); Seriwe Bay; 08°51.960´S, 116°32.838´E;  25 Mar. 2014; station 146;  Avicenniamangrove with hard mud and rocks; UMIZ 0 0 132• 1 spec. (18/10 [2960] mm); same data as for preceding; UMIZ 0 0 139. –   Bali• 1 spec. (25/14 [3051] mm); Denpasar; 08°47.435´S, 115°13.197´E;  1 Apr. 2014; station 153; large mangrove by road, very soft mud; UMIZ 0 0 133• 1 spec. (30/20 [3070] mm); Denpasar; 08°46.126´S, 115°10.803´E;  2 Apr. 2014; station 154; large mangrove by road, with shallow mud; UMIZ 0 0 134.–   Halmahera• 1spec. (25/15 [5082] mm); Akelamo; 01°01.329´N, 127°39.091´E;  10 Mar. 2015; station 207; sandymuddy beach at margin of mangrove near village; UMIZ0 0 135• 2 spec. (50/35 [5102] and 55/35 [5103] mm); Buli; 00°55.446´N, 128°20.612´E;  16 Mar. 2015; station 212; logged area in front of old  Rhizophoraforest, by the road; UMIZ 0 0 136• 1 spec. (55/30 [5042] mm); Buli; 00°55.367´N, 128°20.647´E;  17 Mar. 2015; station 213; tall and old  Rhizophoraforests, high intertidal; UMIZ 0 0 137.   JAPAN• 1 spec. (22/10 [3761] mm); Ehime Prefecture, Misho Bay; 32°57.634´N, 132°33.205´E;  4 Aug. 2014; station o28; mudflats; NSMT Mo 78984.   MALAYSIA• 1 spec. (40/25 [963] mm); Peninsular Malaysia, Nibong Tebal, Pulau Burung; 05°12.488´N, 100°25.564´E;  11 Jul. 2011; station 17; soft mud, open mangrove of  Rhizophora, with a few  Sonneratia; USMMC 0 0 0 57•  1spec. (18/12 [928] mm); E Peninsular Malaysia, Balok; 03°53.219´N, 103°21.978´E;  14 Jul. 2011; station 19; mostly  Rhizophora, with some  Avicennia, hard mud with shallow pools, patches of soft mud; USMMC 0 0 0 58.   PAPUA NEW GUINEA• 1 spec. (18/14 [5432] mm); Madang, Meiro River, near airport; 05°12.2´S, 145°47.4´E;  5 Nov. 2012; MNHN expedition Papua Niuginileg.; station PM01;  Nypapalm swamp; MNHN IM-2013-10478• 1 spec. (17/12 [5433] mm); same data as for preceding; MNHN IM-2013- 10479.   PHILIPPINES– Luzon• 1 spec. (26/18 [3610] mm); Lian, Batangas; 13°58.130´N, 120°37.471´E;  5 Jul. 2014; station 179; narrow and impacted mangrove of  Avicennianear village, very sandy, little to no mud; PNM 0 41261• 2 spec. (30/20 [3171] and 25/15 [3192] mm); Nasugbu, Batangas; 14°10.714´N, 120°36.817´E;  6 Jul. 2014; station 182; near village, well-preserved and dense forest of  Avicenniaand  Rhizophora; PNM 0 41255• 1 spec. (22/14 [3172] mm); same data as for preceding; PNM 0 41262• 2 spec. (30/20 [3200] and 35/22 [3205] mm); Calantagan, Batangas; 13°55.319´N, 120°37.260´E;  7 Jul. 2014; station 183; rocks next to  Avicenniaand  Rhizophoraforest; PNM 0 41256• 1 spec. (30/18 [3202] mm); same data as for preceding; PNM 0 41263• 1 spec. (35/22 [3222] mm); Calantagan, Batangas; 13°53.278´N, 120°37.124´E;  8 Jul. 2014; station 184; narrow forest on the shore,  Avicenniaand young  Rhizophora; PNM 0 41257• 1 spec. (33/15 [3229] mm); same data as for preceding; PNM 0 41264• 1 spec. (27/18 [3237] mm); Calantagan, Batangas; 13°51.264´N, 120°37.383´E;  8 Jul. 2014; station 185; next to village, impacted, narrow  Avicenniamangrove by the shore; PNM 0 41265. –   Bohol• 1 spec. (40/25 [3344] mm); Mabini; 09°51.532´N, 124°31.685´E;  17 Jul. 2014; station 194; narrow mangrove on edge of fish ponds, tall  Rhizophoraand  Avicenniatrees, many old logs; PNM 0 41258• 1 spec. (26/15 [3371] mm); Mabini; 09°51.586´N, 124°34.155´E;  18 Jul. 2014; station 196;  Avicenniaand  Sonneratiaopen forest with sand, algae and coral rubble; PNM 0 41259• 1 spec. (30/18 [3416] mm); Maribojoc; 09°44.280´N, 123°49.389´E;  20 Jul. 2014; station 202; uplifted coral rubble with sand and algae, near  Sonneratiatrees; PNM 0 41260.   VIETNAM• 2 spec. (45/30 [5619] and 40/30 [5682] mm); Nha Trang; 12°12.778´N, 109°09.572´E;  27 Jul. 2015; station 237; small strip of mud with a few  Rhizophoratrees next to a small river, by fish ponds and houses; ITBZC IM 0 0 0 19• 1 spec. (25/15 [5642] mm); Nha Trang; 12°24.168´N, 109°10.058´E;  29 Jul. 2015; station 239; mostly  Avicenniaand some small  Rhizophora, with shallow mud; ITBZC IM 0 0 0 20.   Color and morphology of live animals( Figs 7–10) Live animals of units #1 and #2 are often abundantly covered with mud, in which case their dorsal color can hardly be seen. The background of the dorsal notum is brown, light to dark. That background can be homogenous or clearly mottled with darker or lighter areas and, occasionally, also with red areas. In addition, in some animals the tip of the dorsal papillae (with and without dorsal eyes) can be bright yellow. The foot varies from gray (light or dark) to yellow or orange. The hyponotum is almost always yellow, from pale yellow to bright yellow and even orange. This variable yellow component can cover the entire hyponotum or just an outer ring (the inner ring being light to dark gray). The color of the foot and of the hyponotum of an individual can change rapidly, especially when disturbed. The ocular tentacles are brown (variable from light to dark) and may or may not be speckled with tiny white dots, exactly like the head. The ocular tentacles are short (just a few millimeters long).   Fig. 7.  Paromoionchis tumidus(Semper, 1880) comb. nov.unit #1, live animals. A. Dorsal view, 35 mm long [3205], Philippines, Luzon (PNM 041256). B. Dorsal view, 40 mm long [5682], Vietnam (ITBZC IM 00019). C. Dorsal view, 33 mm long [3222], Philippines, Luzon (PNM 041257). D. Dorsal view, 54 mm long [5042], Indonesia, Halmahera (UMIZ 00137). E. Dorsal view, 30 mm long [1705], Australia, Northern Territory (NTM P.57622). F. Dorsal view, 26 mm long [2875], Indonesia, Seram (UMIZ 00130). G. Dorsal view, 17 mm long [2627], Australia, Queensland (MTQ). H. Dorsal view, 27 mm long [1755], Indonesia, Sumatra (UMIZ 00122).   Fig. 8.  Paromoionchis tumidus(Semper, 1880) comb. nov.unit #1, live animals. A. Dorsal view, 55 mm long [5103], Indonesia, Halmahera (UMIZ 00136). B. Dorsal view, 22 mm long [1732], Indonesia, Sumatra (UMIZ 00121). C. Dorsal view, 22 mm long [5082], Indonesia, Halmahera (UMIZ 00135). D. Dorsal view, 22 mm long [5642], Vietnam (ITBZC IM 00020). E. Dorsal view, 45 mm long [2657], Australia, Queensland (MTQ). F. Dorsal view, 31 mm long [1522], Australia, New South Wales (AM C.468918.005). G. Ventral view, 42 mm long [1686], Australia, Northern Territory (NTM P.57621). H. Ventral view, 47 mm long [2562], Australia, Queensland (MTQ). I. Ventral view, 19 mm long [2961], Indonesia, Lombok (UMIZ 00132). J. Ventral view, 44 mm long [5619], Vietnam (ITBZC IM 00019). K. Ventral view, 33 mm long [3416], Philippines, Bohol (PNM 041260). L. Ventral view, 24 mm long [3371], Philippines, Bohol (PNM 041259).   Fig. 9.  Paromoionchis tumidus(Semper, 1880) comb. nov.unit #2, live animals. A. Dorsal view, 38 mm long [1651], Australia, Northern Territory (NTM P.57624). B. Dorsal view, 32 mm long [3237], Philippines, Luzon (PNM 041265). C. Dorsal view, 45 mm long [1638], Australia, Northern Territory (NTM P.57623). D. Dorsal view, 43 mm long [1794], Indonesia, Sumatra (UMIZ 00138). E. Dorsal view, 17 mm long [2960], Indonesia, Lombok (UMIZ 00139). F. Dorsal view, 27 mm long [3610], Philippines, Luzon (PNM 041261). G. Ventral view, same as C. H. Ventral view, same as D. I. Ventral view, 32 mm long [3229], Philippines, Luzon (PNM 041264). No live pictures were available for unit #3, so the following description is based on preserved specimens ( Fig. 10). It is possible that bright colors (yellow, orange) were lost during preservation on both the ventral and dorsal sides. The background of the dorsal notum is brown, mottled with darker or lighter areas. The foot is light gray. The hyponotum is gray-brown, with a reddish hue on the margin (which could possibly be orange in live animals). The color of the ocular tentacles (retracted, likely short) cannot be determined. Generally speaking, the dorsal notum of any given live animal can rapidly change from almost perfectly smooth to covered by many papillae. However, when animals are not disturbed, the dorsum is usually covered by papillae of various sizes. In some animals, larger papillae may be arranged in two longitudinal and lateral ridges (on either side of the median line), but those ridges can appear and disappear rapidly. Some papillae bear from two to four black dorsal eyes at their tip (most papillae bear three eyes). The number of papillae with dorsal eyes is variable (between 10 and 15, on average) and they mostly are on the central part of the notum. Their tip is usually yellow, but not always. A central, much larger papilla, which bears four dorsal eyes (sometimes three), is entirely retractable within the notum. In addition to all these large papillae, the notum is covered by smaller, rounded papillae, which can make it look granular.  External morphology( Fig. 11A–B) Preserved specimens no longer display the color of live animals. The body is not flattened (although, exceptionally, animals on mud with a thin layer of water can look flattened). The notum is oval. Dorsal gills are absent. The large, central, retractable papilla at the center of the notum can only be seen in live animals. In preserved specimens, it is retracted inside the notum. The hyponotum is horizontal. The width of the hyponotum relative to the total width of the ventral surface (pedal sole and hyponotum) varies among individuals, from approximately one third to half. In the anterior region, the left and right ocular tentacles are superior to the mouth. Eyes are located at the tip of the two ocular tentacles. Inferior to the ocular tentacles, superior to the mouth, the head bears a pair of oral lobes. The latter are smooth, with no transversal protuberance. The male opening (of the copulatory complex) is below and to the left of the right ocular tentacle (i.e., between the two ocular tentacles). The anus is posterior, median, close to the edge of the pedal sole. On the right side (to the left in ventral view), a peripodial groove is present at the junction between the foot and the hyponotum, running longitudinally from the buccal area to the posterior end, a few millimeters from the anus and the pneumostome. The pneumostome is median. Its position on the hyponotum relative to the notum margin and the edge of the pedal sole varies among individuals but averages in the middle. The position of the female pore (at the posterior end of the peripodial groove) does not vary much among individuals.   Fig. 10.  Paromoionchis tumidus(Semper, 1880) comb. nov.unit #3, preserved specimens, Papua New Guinea, Madang. A. Dorsal view, 13 mm long [5432] (MNHN IM-2013-10478). B. Lateral view, same as A. C. Ventral view, same as A. D. Dorsal view, 14 mm long [5433] (MNHN IM-2013-10479).   Visceral cavity and pallial complex The anterior pedal gland is oval and flattened, lying free on the floor of the visceral cavity below the buccal mass. The heart, enclosed in the pericardium, is on the right side of the visceral cavity, slightly posterior to the middle. From the anterior ventricle an anterior vessel exits that supports several anterior organs such as the buccal mass, the nervous system and the copulatory complex. The auricle is posterior. The kidney is more or less symmetrical, the right and left parts being equally developed. The kidney is intricately attached to the respiratory complex. The lung is in two more or less symmetrical parts, left and right.  Digestive system( Figs 12–15) There are no jaws. The left and right salivary glands, heavily branched, join the buccal mass dorsally, on either side of the esophagus. The radula is in between two large postero-lateral muscular masses. Radulae measure up to 5.2 mmin length (unit #1), 4.1 mm(unit #2) and 2.8 mm(unit #3). Each radular row contains a rachidian tooth and two half rows of lateral teeth of similar size and shape. Examples of radular formulae are presented in Table 4. The rachidian teeth are unicuspid: the median cusp is always present; there are no conspicuous cusps on the lateral sides of the base of the rachidian tooth. The length of the rachidian teeth (approximately 25 µm) tend to be approximately half the size of the lateral teeth (approximately 50 µm). The lateral aspect of the base of the rachidian teeth is straight, occasionally slightly convex. The half rows of lateral teeth form an angle of 45° with the rachidian axis. With the exception of the few innermost and few outermost lateral teeth, the size and shape of the lateral teeth do not vary along the half row, nor do they vary among half rows. The lateral teeth seem to be unicuspid with a flattened and curved hook (approximately 50 µm long) with a rounded tip, but there is also a pointed spine on the outer lateral expansion of the base (basal lateral spine). In most cases, the basal lateral spine cannot be observed because it is hidden below the hook of the next, outer lateral tooth. It can only be observed when the teeth are not too close (such as in the innermost and outermost regions) or when teeth are placed in an unusual position. The inner and outer lateral aspects of the hook of the lateral teeth are straight (i.e., not wavy and not with any protuberance).   Fig. 11.  Paromoionchis tumidus(Semper, 1880) comb. nov., external morphology and nervous system. A. Anterior, ventral view, lectotype of  Onchidium mertoniSimroth, 1918(ZMB 121591a). B. Unit #1, posterior, ventral view, Indonesia, Sulawesi [2240] (UMIZ 00125). C. Nervous system, dorsal view, same as B. Abbreviations: a = anus; f = foot; fo = female opening; h = hyponotum; lcg = left cerebral ganglion; lplg = left pleural ganglion; mo = male opening; ol = oral lobe; ot = ocular tentacle; pn = pneumostome; ppg = peripodial groove; rcg = right cerebral ganglion; rplg = right pleural ganglion; vg = visceral ganglion. Scales: A–B = 2 mm; C = 0.5 mm.   Fig. 12.  Paromoionchis tumidus(Semper, 1880) comb. nov., digestive system. A. Unit #1, dorsal view, Indonesia, Sulawesi [2240] (UMIZ 00125). B. Ventral view (lateral digestive gland removed), same as A. C. Stomach, dorsal view, same as A. D. Dorsal view (digestive gland removed prior to present study, intestinal loops loose), holotype of  Onchidium honkongenseBritton, 1984(NHM 1982290). E. Unit #2, dorsal view, Australia, Northern Territory [1638] (NTM P.57623). F. Unit #3, dorsal view, Papua New Guinea, Madang [5433] (MNHN IM-2013-10479). G. Dorsal view, lectotype of  Onchidium mertoniSimroth, 1918(ZMB 121591a). H. Dorsal view, lectotype of  Onchidium tumidum(ZMB 39019a). I. Dorsal view, lectotype of  Onchidium samarenseSemper, 1880(ZMB 39025a). Abbreviations: ddg = dorsal lobe of digestive gland; i = intestine; oddg = opening of dorsal lobe of digestive gland; oldg = opening of lateral lobe of digestive gland; opdg = opening of posterior lobe of digestive gland; pdg = posterior lobe of digestive gland; r = rectum; st = stomach; st1 = stomach chamber 1; st2 = stomach chamber 2; st3 = stomach chamber 3; st4 = stomach chamber 4. Scales: A–C, F = 2 mm; D, I = 3 mm; E = 5 mm; G = 1 mm; H = 4 mm.   Table 4.Radular formulae for the five species of  Paromoionchis gen. nov.following the same format: number of rows × (number of lateral teeth per left half row - 1 rachidian tooth - number of lateral teeth per right half row). Each DNA extraction number corresponds to one particular individual. DNA extraction numbers are used on Figs 1–4 (the phylogenetic trees), Table 1 and in the material examined section for each species.     Species  Radular formula  Spm length (mm)  Voucher  DNA extraction number    P. tumidusunit #1 70 × 80-1-80 55 MTQ 2637  – 65 × 60-1-60 50 UMIZ 0 0 136 5102  – 60 × 75-1-75 40 PNM 0 41258 3344  – 55 × 80-1-80 45 NTM P.57620 1634  – 55 × 80-1-80 20 UMIZ 0 0 123 1798  – 55 × 65-1-65 45 UMIZ 0 0 129 2832  – 55 × 65-1-65 35 PNM 0 41256 3205  – 50 × 60-1-60 30 UMIZ 0 0 131 2950  – 50 × 60-1-60 25 UMIZ 0 0 133 3051    P. tumidusunit #2 65 × 105-1-105 42 NTM P.57623 1638  – 60 × 85-1-85 27 PNM 0 41265 3237  – 45 × 65-1-65 22 PNM 0 41262 3172    P. tumidusunit #3 60 × 65-1-65 18 MNHN IM-2013-10478 5432  – 50 × 60-1-60 17 MNHN IM-2013-10479 5433    P. daemelii 75 × 105-1-105 60 AM C.468917.001 1519  – 70 × 90-1-90 50 AM C.468919.001 1521  – 55 × 60-1-60 17 AM C.468911.001 1510    P. boholensisunit #1 70 × 80-1-80 28 PNM 0 41266 3288 Holotype  – 65 × 85-1-85 35 PNM 0 41269 3372  – 60 × 70-1-70 16 PNM 0 41268 3283    P. boholensisunit #2 65 × 90-1-90 35 UMIZ 0 0 140 3117  – 60 × 85-1-85 18 UMIZ 0 0 149 2911  – 60 × 80-1-80 45 UMIZ 0 0 146 2851    P. penangensis 60 × 70-1-70 48 USMMC 0 0 0 62 6020  – 55 × 60-1-60 30 USMMC 0 0 0 60 5991  – 50 × 60-1-60 26 USMMC 0 0 0 59 6037 Holotype    P. goslineriunit #1 65 × 65-1-65 22 PNM 0 41272 3221  – 60 × 70-1-70 25 PNM 0 41271 3233 Holotype  – 55 × 75-1-75 28 PNM 0 41273 3232  – 60 × 70-1-70 20 PNM 0 41272 6049    P. goslineriunit #2 55 70-1-70 22 UMIZ 0 0 155 3078  – 55 × 60-1-60 35 UMIZ 0 0 159 5145  – 50 × 65-1-65 18 UMIZ 0 0 153 2241 The esophagus is narrow and straight, with thin internal folds. The esophagus enters the stomach anteriorly. Only a portion of the posterior aspect of the stomach can be seen in dorsal view because it is partly covered by the lobes of the digestive gland. The dorsal lobe is mainly on the right. The left, lateral lobe is mainly ventral. The posterior lobe covers the posterior aspect of the stomach. The stomach is a U-shaped sac divided into four chambers. The first chamber, which receives the esophagus, is delimited by thin tissue and receives the ducts of the dorsal and lateral lobes of the digestive gland. The second, posterior chamber, delimited by thick muscular tissue, receives the duct of the posterior lobe of the digestive gland. The third, funnel-shaped chamber is delimited by thin tissue with high ridges internally. The fourth chamber is continuous and externally similar to the third, but it bears only low, thin ridges internally. The intestine is long and narrow and the intestinal loops are of typeII. There is no rectal gland.  Nervous system( Fig. 11C) The circum-esophageal nerve ring is post-pharyngeal and pre-esophageal. The paired cerebral ganglia are close and the cerebral commissure is short (but its length does vary among individuals). Paired pleural and pedal ganglia are also all distinct. The visceral commissure is short but distinctly present and the visceral ganglion is more or less median. Cerebro-pleural and pleuro-pedal connectives are short and pleural and cerebral ganglia touch each other on either side. Nerves from the cerebral ganglia innervate the buccal area and the ocular tentacles and, on the right side, the penial complex. Nerves from the pedal ganglia innervate the foot. Nerves from the pleural ganglia innervate the lateral and dorsal regions of the mantle. Nerves from the visceral ganglia innervate the visceral organs.   Fig. 13.  Paromoionchis tumidus(Semper, 1880) comb. nov.unit #1, radula, Indonesia, Bali [3051] (UMIZ 00133). A. Rachidian and innermost lateral teeth. B. Lateral teeth with rachidian teeth. C. Lateral teeth. D. Outermost lateral teeth. Abbreviations: 1llt = first left lateral tooth; 1rlt = first right lateral tooth; 2llt = second left lateral tooth; 2rlt = second right lateral tooth; bls = basal lateral spine; hlt = hook of lateral tooth; mc = median cusp; rt = rachidian tooth. Scales: A = 20 μm; B = 30 μm; C = 50 μm; D = 10 μm.   Fig. 14.  Paromoionchis tumidus(Semper, 1880) comb. nov.unit #2, radula, Australia, Northern Territory [1638] (NTM P.57623). A. Rachidian and innermost lateral teeth. B. Lateral teeth with rachidian teeth. C. Lateral teeth. D. Outermost lateral teeth. Scales: A = 30 μm; B–C = 50 μm; D = 20 μm.   Fig. 15.  Paromoionchis tumidus(Semper, 1880) comb. nov.unit #3, radula, Papua New Guinea, Madang. A. Rachidian and innermost lateral teeth, [5432] (MNHN IM-2013-10478). B. Lateral teeth with rachidian teeth, same as A. C. Lateral teeth, same as A. D. Outermost lateral teeth, [5433] (MNHN IM-2013-10479). Scales: A = 10 μm; B, D = 20 μm; C = 25 μm.  Reproductive system(  Figs 16–23) Sexual maturity is correlated with animal length. Mature individuals have large female organs (with a large female gland mass) and fully-developed male copulatory parts. Immature individuals (< 15 mmlong) may have inconspicuous (or no) female organs and rudimentary anterior male parts.   Fig. 16.  Paromoionchis tumidus(Semper, 1880) comb. nov.unit #1, reproductive system. A. Posterior hermaphroditic (female) reproductive system, Australia, Northern Territory [1634] (NTM P.57620). B. Male copulatory organs, Philippines, Bohol [3344] (PNM 041258). C. Male copulatory organs, lectotype of  Onchidium tumidum(ZMB 39019a). Abbreviations: ag = accessory penial gland; dd = deferent duct; fgm = female gland mass; hd = hermaphroditic duct; hg = hermaphroditic gland; ms = muscular sac (of accessory penial gland); ov = oviduct; ps = penial sheath; rm = retractor muscle; rs = receptaculum seminis; sp = spermatheca; v = vestibule. Scales = 3 mm. The female organs are located at the posterior end of the visceral cavity, mixed with some male parts ( Figs 16A, 17A–B). The hermaphroditic gland is a single mass, joining the spermoviduct through the hermaphroditic duct (which conveys the eggs and the autosperm). There is a narrow and bent receptaculum seminalis (caecum) along the hermaphroditic duct. The female gland mass contains various glands (mucus and albumen) which can hardly be separated by dissection and of which the exact connections remain uncertain. The hermaphroditic duct becomes the spermoviduct (which conveys eggs, exosperm and autosperm). Proximally, the spermoviduct is not divided (at least externally) and is embedded within the female gland mass. Distally, the spermoviduct branches into the deferent duct (which conveys the autosperm up to the anterior region, running through the body wall) and the oviduct. The free oviduct conveys the eggs up to the female opening and the exosperm from the female opening up to the fertilization chamber. The large, ovate-spherical spermatheca connects to the oviduct through a narrow and short duct. The oviduct is narrow and straight. There is no vaginal gland.   Fig. 17.  Paromoionchis tumidus( Semper, 1880) comb. nov., reproductive system. A. Unit #3, posterior hermaphroditic (female) reproductive system, Papua New Guinea, Madang[5433] (MNHN IM- 2013-10479). B. Unit #2, posterior hermaphroditic (female) reproductive system, Australia, Northern Territory[1638] (NTM P.57623). C. Male copulatory organs, same as A. D. Male copulatory organs, same as B. Abbreviations: ag = accessory penial gland; dd = deferent duct; fgm = female gland mass; hd = hermaphroditic duct; hg = hermaphroditic gland; ms = muscular sac (of accessory penial gland); ov = oviduct; ps = penial sheath; rm = retractor muscle; rs = receptaculum seminis; sp = spermatheca; v = vestibule. Scales: A, C = 1 mm; B, D = 3 mm.   Fig. 18.  Paromoionchis tumidus( Semper, 1880) comb. nov.unit #1, spine of accessory penial gland. A. Indonesia, Lombok [2950] (UMIZ 00131). B. Philippines, Bohol[3344] (PNM 041258). C. Indonesia, Ambon[2832] (UMIZ 00129). D. Australia, Northern Territory[1634] (NTM P.57620). E. Australia, Queensland[2637] (MTQ). F. Distal tip of spine, Indonesia, Halmahera [5102] (UMIZ 00136). G. Distal tip of spine, same as D. Scales: A–D = 200 μm; E = 400 μm; F–G = 20 μm.   Fig. 19.  Paromoionchis tumidus( Semper, 1880) comb. nov.unit #2, spine of accessory penial gland. A. Australia, Northern Territory[1638] (NTM P.57623). B. Philippines, Luzon [3237] (PNM 041265). C. Philippines, Luzon [3172] (PNM 041262). D. Distal tip of spine, same as A. E. Distal tip of spine, same as B. F. Distal tip of spine, same as C. Scales: A = 150 μm; B–C = 200 μm; D–F = 20 μm.   Fig. 20.  Paromoionchis tumidus( Semper, 1880) comb. nov.unit #3, spine of accessory penial gland, Papua New Guinea, Madang. A. [5432] (MNHN IM-2013-10478). B. [5433] (MNHN IM-2013-10479). C. Distal tip of spine, same as A. Scales: A = 100 μm; B = 20 μm; C = 10 μm.   Fig. 21.  Paromoionchis tumidus( Semper, 1880) comb. nov.unit #1, penial hooks. A. Indonesia, Sulawesi[2240] (UMIZ 00125). B. Indonesia, Ambon[2832] (UMIZ 00129). C. Lectotypeof  Onchidium mertoni Simroth, 1918(ZMB 121591a). D. Lectotypeof  Onchidium tumidum(ZMB 39019a). Scales: A = 60 μm; B = 10 μm; C = 4 μm; D = 25 μm.   Fig. 22.  Paromoionchis tumidus( Semper, 1880) comb. nov.unit #2, penial hooks. A. Indonesia, Sumatra[1794] (UMIZ 00138). B. Philippines, Luzon [3237] (PNM 041265). C. Same as B. Scales: A = 20 μm; B = 4 μm; C = 6 μm. The male anterior organs consist of the penial complex (penis, penial sheath, vestibule, deferent duct, retractor muscle) and the accessory penial gland ( Figs 16B–C, 17C–D). The penial complex and the accessory penial gland share the same vestibule and the same anterior male opening. The penial gland is a long, tube-like flagellum with a proximal dead end. The length of the flagellum of the penial gland varies among individuals but it is always heavily coiled. Near its distal end (just before the hollow spine), the flagellum is enlarged into a thick muscular sac. Distally, the flagellum ends in a hard, hollow spine protected by a sheath which opens into the vestibule. The hollow spine is narrow, elongated and slightly curved ( Figs 18–20). Its base is conical. Its diameter is between 60 and 100 μm. The diameter of the opening at its tip measures between 30 and 60 μm. Its length ranges from 1 mm([1634] NTM P.57620) to 2 mm([5619] ITBZC IM 0 0 0 19, [5102] UMIZ 00136) for unit #1, from 1.2 mm([1638] NTM P.57623) to 1.8 mm([3237] PNM 0 41265, [3172] PNM 041262) for unit #2 and from 0.8 mm([5433] MNHN IM-2013-10479) to 1 mm([5432] MNHN IM-2013-10478) for unit #3, and its shape does vary between individuals ( Figs 18–20). There is no disc separating the spine of the penial gland and the vestibule. The penial sheath is narrow and elongated ( Figs 16B–C, 17C–D). The penial sheath protects the penis for its entire length. The beginning of the retractor muscle marks the separation between the penial sheath (and the penis inside) and the deferent duct. The retractor muscle is shorter than the penial sheath and inserts on the wall of the body cavity, near the heart. The deferent duct is also highly convoluted, with many loops. Inside the penial sheath, the penis is a narrow, elongated, soft, hollow tube of approximately 200 μm in diameter. Inside the tube-like penis, six longitudinal ridges bear sparse, tiny, conical (but not pointed) hooks which are less than 20 μm long in unit #1, less than 22 μm long in unit #2 and less than 28 μm in unit #3 ( Figs 21–23). When the penis is retracted inside the penial sheath, the hooks are inside the tube-like penis; during copulation, the penis is evaginated like a glove and the hooks are outside.    Distinctive diagnostic features Externally,  Paromoionchis tumidus( Semper, 1880)cannot be distinguished from other species of  Paromoionchis gen. nov.Internally, the presence of penial hooks distinguishes it from other species of the genus ( Table 3).   Distribution( Fig. 6) All records here are new, except for the typelocalities. Unit #1. Australia: New South Wales, Northern Territory, Queensland. Brunei Darussalam. Hong Kong( typelocality of  Onchidium hongkongense). India: Andaman Islands. Indonesia: Ambon, Aru Islands, Bali, Halmahera, Lombok, Seram, Sulawesi, Sumatra. Japan. Malaysia: Peninsular Malaysia. Singapore( typelocality of  Onchidium tumidum). Philippines: Bohol, Luzon, Samar( typelocality of  Onchidium samarense). Vietnam.The southernmost locality is in Sydney, New South Wales, Australia( 33°37.323´S) and the northernmost locality is in Misho Bay, Ehime Prefecture, Japan( 32°57.634´N). Unit #2. Australia: Northern Territory. Indonesia: Sumatra, Lombok. Philippines: Luzon. Unit #3. Papua New Guinea: Madang.   Habitat( Figs 24–25)   Paromoionchis tumidusunit #1 is predominantly found on mud, hard or soft, inside or near mangroves, or on mudflats ( Fig. 24). It is also found on old, muddy logs, inside or near mangroves. It occasionally is found on muddy sand, or even rocks and coral rubble, usually in the proximity of some mangrove trees. It is not found on rocky shores.  Paromoionchis tumidusunit #2 is found in mangroves, mostly on mud and occasionally on sand ( Fig. 25).  Paromoionchis tumidusunit #3 is found in  Nypapalm swamps and seems rare (only two specimens are known).   Paromoionchis tumidusis very common across its entire distribution range. It is by far the most abundant species of  Paromoionchis gen. nov.and arguably the most abundant onchidiid species in the Indo-West Pacific. Most individuals of  P. tumidusare part of unit #1, because  P. tumidusunit #2 is rare across its entire distribution (it is only known from a total of nine specimens collected at nine stations) and  P. tumidusunit #3 is restricted to two individuals from Papua New Guinea.    Remarks The publication dates of the various sections of the volume on Landmolluskenby Carl Semper in the Reisen im Archipel der Philippinenseries were clarified by Johnson (1969). The species name  Onchidium tumidumwas published by Semper with a complete description (text and figures) in 1880. The anatomy of the species described here is fully compatible with Semper’s original description of  Onchidium tumidumas well as our own observation of the lectotype(and paralectotypes) from Singapore( Table 3). The most important characters are the lack of a rectal gland, a digestive system of type II, an accessory penial gland, a retractor muscle of the penis inserting near the heart, a male opening between the two eye tentacles (not just below the right eye tentacle), and a penis with hooks ( Figs 12H, 21D). According to Semper (1880: 263, our translation), the male opening is “almost exactly midway between the two [eye tentacles],” but it actually is closer to the right tentacle. Also, Semper (1880: 263, our translation)described a penis with an “anterior tooth-bearing portion [which] is reduced, namely at most 2 mmlong.” It is confirmed here with SEM ( Fig. 21D) that the penis of the lectotypebears tiny hooks (<20 μm) and is fully compatible with the species described here. The lectotypeof  O. mertoniis anatomically identical to the species described here,  P. tumidus. Simroth did not describe the internal anatomy of  O. mertoni, but a description of its lectotypeis provided here. Simroth mentioned a male aperture below the right ocular tentacle, but it clearly is to the left of the right tentacle ( Fig. 11A); the intestinal loops are of type II; the male apparatus includes an accessory penial gland; the penial retractor muscle inserts to the body wall near the heart; the penis bears tiny hooks which are identical to the hooks of the species described here ( Fig. 21C).   Fig. 24.  Paromoionchis tumidus( Semper, 1880) comb. nov.unit #1, habitats. A. Australia, Queensland, mangrove by creek with  Rhizophoraand  Avicennia(station 119). B. Indonesia, Ambon, mangrove with large  Rhizophoraand some open spaces between trees (station 131). C. Indonesia, Lombok, mudflat at the margin of mangrove (station 145). D. Philippines, Bohol, narrow forest on the edge of fish ponds, with tall  Rhizophoraand  Avicenniatrees, and different types of mud (station 194). E. Indonesia, Halmahera, logged area by an old  Rhizophoraforest (station 212). F. Vietnam, Nha Trang, mostly  Avicenniatrees, mud not deep (station 239). The type material of  O. hongkongenseis anatomically identical to the species described here and it is characterized by the exact same combination of characters: no rectal gland, intestinal loops of typeII ( Fig. 12D), an accessory penial gland, a retractor muscle inserting near the heart, a male opening between the two eye tentacles and a penis with tiny hooks (which Britton illustrated and measured as <20 μm). Strictly speaking,  Onchidium samarenseprobably should be regarded as a nomen dubium because 1) the jar with the type material includes three specimens while Semper only mentioned two specimens in the original description, 2) the male organs of two of the syntypesare gone (possibly dissected by Semper) and cannot be checked, and 3) important features (e.g., the insertion of the retractor muscle) are not mentioned in the original description. However, our observations are compatible with the original description and it is possible that all three specimens were actually identified as  O. samarenseby Semper himself. According to Semper (1882: 269, our translation), the penis of  O. samarenseis “very similar to that of  O. tumidum.” Indeed, the male apparatus of the lectotypeis very similar to that of the species described here. In particular, the retractor muscle of the penis (not described by Semper) is thin but reaches the heart, following some nerves, as in the species described here. Semper described no ʻcartilaginous teeth.’ However, that can be easily explained by the fact that the hooks inside the penis of  O. tumidumare soft and tiny (<20 μm) and, unlike the large and solid hooks found in some other onchidiids, can hardly be seen under a light microscope (in fact, because there are not many hooks, they are hard to find even with SEM). Our collections currently do not include any specimen from Samar, the type locality of  O. samarense, but we did collect many species of onchidiids in Luzon, just next to Samar, as well as in Bohol, a bit further south in the Philippines. Given the anatomy of  O. samarense(no rectal gland, digestive system of type II, male opening clearly on the left of the right eye tentacle, accessory penial gland and retractor muscle inserting near the heart), it is most likely that  O. samarenseapplies to the same species as  O. tumidum. Because its nomenclatural status still remains problematic (it could be regarded as a nomen dubium) and because its written description was published in 1882 and not in 1880,  O. samarenseis regarded as a junior synonym of  O. tumidum.   Fig. 25.  Paromoionchis tumidus( Semper, 1880) comb. nov.unit #2, habitats. A. Australia, Northern Territory, large mangrove of  Sonneratia, Rhizophoraand Ceriops(st. 66). B. Indonesia, Sumatra, small patch of mangrove, very impacted (st. 81). C. Indonesia, Lombok, open  Avicenniamangrove (station 146). D. Philippines, Luzon, narrow and very sandy  Avicenniamangrove, with no mud (st. 179).  Plate (1893)identified five specimens from Ponape(now Pohnpei, Micronesia) and one specimen from Singaporeas  Onchidium tumidum. Given that their intestinal loops were of typeI, the specimens from Ponapewere misidentified. It is impossible to determine whether the specimen from Singapore(with intestinal loops of typeII) actually belongs to  P. tumidus. Bretnall (1919)listed previous records but did not examine any new material. Bretnall also suggested that  Onchidium punctatumQuoy & Gaimard, 1832could possibly refer to the same species as  O. tumidum. However,  O. punctatumclearly belongs to the genus  Peronia. In fact, it was transferred to  ScaphisLabbé, 1934by Labbé (1934a: 203)as  Scaphis punctataand  Scaphisis a junior synonym of  Peronia. Hoffmann (1928)mentioned  O. tumidum,  O. samarenseand  O. mertonibut did not examine any new material. Hoffmann also suggested that the record of  Onchidium tabularis( Tapparone-Canefri, 1883), listed by Boettger (1923)from the Aru and Kei Islands, was a misidentification for  O. mertoni(Boettger provided a record but did not describe any specimens). However, Hoffmann’s claim cannot be checked because the application of  Onchidella tabularis Tapparone-Canefri, 1883(as  Oncidiella) is very unclear (the typematerial could not be located and the original description is not informative). Three onchidiid sequences from mainland Chinawere obtained from GenBank, the only ones that are not new in our data set ( Table 1). These sequences were misidentified as  Paraoncidium reevesii(J.E. Gray, 1850).  ParaoncidiumLabbé, 1934is not a valid name: it is a junior synonym of  OnchidinaSemper, 1882. Also,  Onchidium reevesi(J.E. Gray, 1850)is actually one of the three valid species of  Onchidium( Dayrat et al.2016). 2005432460 [189,997,686,713] ZMB Singapore SINGAPORE 21 22 1 lectotype 2005720723 [1021,1398,686,713] ZMB 21 22 ZMB 39019b 15 paralectotype 2005432481 [207,598,721,748] NHMD Singapore 21 22 NHMD 300305 2 paralectotype 2005432471 [623,999,721,747] SMF Singapore 21 22 SMF 333603 1 paralectotype 2005432464 [189,996,787,813] ZMB Australia Mackay 21 22 2 Queensland paralectotype 2005432461 ZMB Philippines Palapa Island 21 22 1 Samar lectotype 2005432477 ZMB Philippines Palapa Island 21 22 2 Samar paralectotype 2005432475 1908-01-05 ZMB Indonesia Sungai Aru Islands Kobroor 21 22 ZMB 121591 1 lectotype 2005432472 14 / 8, 14 / 10, 15 / 14 and 14 / 10 ZMB Indonesia Sungai Aru Islands Kobroor 21 22 ZMB 121591 4 paralectotype 2005432470 [189,1223,1159,1186] NHM China CHINA 21 22 NHM 1982290 1 holotype 2005432483 NHM China CHINA 21 22 NHM 1982291, 1982292 15 paratype 2005634576 2011-11-24 Australia Sydney -33.62205 Careel Bay 1 151.3313 Pittwater 22 23 1 New South Wales 2005634586 2011-11-25 Australia Sydney -33.51145 Cheero Point 1 151.19449 Hawkesbury River 22 23 1 New South Wales 2005634591 [504,1398,1660,1687] 2011-11-25 Australia Sydney -33.51145 Cheero Point 1 151.19449 Hawkesbury River 22 23 1 New South Wales 2005634589 [208,1102,1695,1722] 2011-11-25 Australia Sydney -33.51145 Cheero Point 1 151.19449 Hawkesbury River 22 23 1 New South Wales 2005634587 2012-08-16 Australia -12.582983 Channel Island 1 130.9332 Darwin 22 23 1 Northern Territory 2005634594 2012-08-17 Australia -12.559283 Channel Island 1 130.88156 Darwin 22 23 1 Northern Territory 2005634598 2012-08-17 Australia -12.559283 Channel Island 1 130.88156 Darwin 22 23 1 Northern Territory 2005634599 2012-08-19 Australia -12.4797 Tiger Brenan Road 1 130.9125 Darwin 22 23 1 Northern Territory 2005634581 2012-08-20 Australia -12.548217 Elizabeth Road 1 130.9607 Darwin 22 23 1 Northern Territory 2005634565 2013-06-17 Australia -16.8093 Knob 1 145.7128 Cairns 23 24 1 Queensland 2005634555 2013-06-24 Australia -19.165634 Magnetic Island 1 146.81715 Townsville 23 24 1 Queensland 2005634583 2013-07-01 Australia -20.010967 Bowen 1 148.26463 23 24 1 Queensland 2005634579 2013-07-01 Australia -20.015217 Bowen 1 148.26242 23 24 1 Queensland 2005634597 2013-07-02 Australia -20.021067 Doughty Creek 1 148.23909 Bowen 23 24 1 Queensland 2005634584 2013-07-03 Australia -20.024633 Bowen 1 148.23706 23 24 1 Queensland 2005634561 2013-07-08 Australia -20.14185 Mackay 1 149.20126 23 24 1 Queensland 2005634590 2002-09-14 Loch, D. L. & A. C. Miller Australia Thirsty Sound -22.135733 Endeavour Park 1 150.03093 Plum Tree 23 24 1 Queensland 2005634574 2011-07-27 Brunei 4.920767 Pulau Pyatan 1 115.04607 Teluk Brunei 23 24 1 2005634578 2011-01-12 India Kadamtala 12.330717 Andaman Islands 1 92.77295 Shantipur 23 24 1 2005634572 2012-10-17 UMIZ Indonesia -5.27125 Kualapenet 1 105.85478 23 24 1 Sumatera Utara 2005634588 2012-10-21 UMIZ Indonesia -5.8426666 Bakauheni 1 105.77 23 24 1 Sumatera Utara 2005634577 [208,1041,1237,1265] 2012-10-21 UMIZ Indonesia -5.8426666 Bakauheni 1 105.77 23 24 1 Sumatera Utara 2005634559 2012-10-28 UMIZ Indonesia -5.5443335 S of Bandar 9 105.251884 23 24 1 Lampung 2005634600 2013-03-12 UMIZ Indonesia 1.6918833 Tamperong 1 125.01328 23 24 1 Sulawesi Utara 2005634596 2013-03-13 UMIZ Indonesia 1.36295 Sondaken 1 124.543236 23 24 1 Sulawesi Utara 2005634592 2013-03-21 UMIZ Indonesia -5.10195 Tallo 1 119.44628 Makassar 23 24 1 Sulawesi Utara 2005720735 forest of mostly Avicennia and Rhizophora, with hard and sandy mud 2013-03-22 UMIZ Indonesia -4.42395 Barru 1 119.59922 23 24 0 0 127 1 Sulawesi Utara 2005720730 mudflat next to small creek in low intertidal of mangrove preserve 2014-02-12 UMIZ Indonesia -4.42395 Lateri 1 119.59922 23 24 0 0 128 1 Sulawesi Utara 2005720718 2014-02-14 UMIZ Indonesia -3.6372833 Lateri 1 128.24638 23 24 1 Sulawesi Utara 2005720729 mud next to a seawall adjacent to a mangrove 2014-02-18 UMIZ Indonesia -3.6372833 Kawa 1 128.24638 23 24 0 0 130 2 Seram 2005720734 Avicennia forest 2014-03-24 UMIZ Indonesia -8.762466 Tanjung Batu village 1 116.0482 23 24 0 0 131 2 Lombok 2005634595 2014-03-25 UMIZ Indonesia -8.866 Seriwe Bay 1 116.5473 23 24 1 Sulawesi Utara 2005634593 [207,1033,1906,1933] 2014-03-25 UMIZ Indonesia -8.866 Seriwe Bay 1 116.5473 23 24 1 Sulawesi Utara 2005634552 2014-04-01 UMIZ Indonesia -8.790584 Denpasar 1 115.21995 23 24 1 Bali 2005720728 2014-04-02 UMIZ Indonesia 24 25 -8.768766 Denpasar 1 115.18005 23 24 1 Bali 2005720732 sandymuddy beach at margin of mangrove near village 2015-03-10 UMIZ Indonesia 1.02215 Akelamo 1 127.65152 24 25 1 1 Halmahera 2005634549 2015-03-16 UMIZ Indonesia 0.9241 Buli 1 128.34354 24 25 1 Bali 2005634557 2015-03-17 UMIZ Indonesia 0.9227833 Buli 1 128.34412 24 25 1 Bali 2005432469 2014-08-04 NSMT Japan 32.960567 Misho Bay 1 132.55342 24 25 1 Ehime 2005634540 2011-07-11 Malaysia 5.208133 MALAYSIA 1 100.42606 24 25 1 2005720731 mostly Rhizophora, with some Avicennia, hard mud with shallow pools, patches of soft mud 2011-07-14 E Peninsular Malaysia USMMC Malaysia 3.8869834 station 19 1 103.3663 Balok 24 25 USMMC, 0 0 0 58 1 2005432459 2012-11-05 MNHN Papua Niugini Papua New Guinea -5.2033334 Meiro River 130 145.79 24 25 PM01, IM-2013-10478 1 Madang 2005432482 2012-11-05 MNHN Papua Niugini Papua New Guinea -5.2033334 Meiro River 130 145.79 24 25 IM-2013- 10479 1 Madang 2005634553 2014-07-05 PNM Philippines 13.968833 Lian 1 120.62452 24 25 1 Batangas 2005634547 2014-07-06 PNM Philippines 14.178567 Nasugbu 1 120.61362 24 25 1 Batangas 2005634546 [535,1378,1127,1154] 2014-07-06 PNM Philippines 14.178567 Nasugbu 1 120.61362 24 25 1 Luzon 2005634564 2014-07-07 PNM Philippines 13.921984 Calantagan 1 120.621 24 25 1 Batangas 2005634585 2014-07-07 PNM Philippines 13.921984 Calantagan 1 120.621 24 25 1 Luzon 2005634551 2014-07-08 PNM Philippines 13.887967 Calantagan 1 120.61874 24 25 1 Batangas 2005634535 [535,1378,1303,1330] 2014-07-08 PNM Philippines 13.887967 Calantagan 1 120.61874 24 25 1 Luzon 2005634554 2014-07-08 PNM Philippines 13.8544 Calantagan 1 120.62305 24 25 1 Batangas 2005634571 2014-07-17 PNM Philippines 9.858867 Mabini 1 124.52808 24 25 1 Bohol 2005634558 2014-07-18 PNM Philippines 9.859767 Mabini 1 124.56925 24 25 1 Bohol 2005634580 2014-07-20 PNM Philippines 9.738 Maribojoc 1 123.82315 24 25 1 Bohol 2005634567 2015-07-27 ITBZC, IM Vietnam 12.212967 Nha Trang 1 109.15953 24 25 1 2005634556 2015-07-29 ITBZC, IM Vietnam 12.4028 Nha Trang 1 109.16763 24 25 1