Paromoionchis goslineri Dayrat & Goulding,

Dayrat, Benoît, Goulding, Tricia C., Khalil, Munawar, Apte, Deepak, Bourke, Adam J., Comendador, Joseph & Tan, Shau Hwai, 2019, A new genus and three new species of mangrove slugs from the Indo-West Pacific (Mollusca: Gastropoda: Euthyneura: Onchidiidae), European Journal of Taxonomy 500, pp. 1-77: 64-67

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Paromoionchis goslineri Dayrat & Goulding

gen. et sp. nov.

Paromoionchis goslineri Dayrat & Goulding  gen. et sp. nov. Figs 45–51View FigView FigView FigView FigView FigView FigView Fig


Paromoionchis goslineri  gen. et sp. nov. is dedicated to Dr. Terry Gosliner, Senior Curator at the California Academy of Sciences, San Francisco, California, USA, who has been exploring the marine life of the Batangas region for many years, where this new species was found, and, more importantly, for years ago providing the first author with a great post-doctoral opportunity to focus on alpha-taxonomy.

Material examined


PHILIPPINES • holotype (25/15 [3233] mm); Luzon, Calantagan , Batangas; 13°51.264´ N, 120°37.383´ E; 8 Jul. 2014; station 185; next to village, impacted narrow mangrove forest of Avicennia  by the shore; PNM 0 41271.GoogleMaps 

Other material

INDONESIA – Sulawesi • 1 spec. (20/14 [2210] mm); Bahoi ; 01°43.355´ N, 125°01.232´ E; 12 Mar. 2013; station 88; sand, small rocks and pieces of wood outside narrow coastal mangrove; UMIZ 0 0 161GoogleMaps  1 spec. (18/10 [2241] mm); Sondaken ; 01°21.777´ N, 124°32.594´ E; 13 Mar. 2013; station 89; mostly Rhizophora  , with sand, small rocks and pieces of wood outside narrow coastal mangrove; UMIZ 0 0 153GoogleMaps  . – Bali • 3 spec. (22/15 [3060], 22/15 [3066] and 27/20 [3068] 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 154GoogleMaps  4 spec. (20/12 [3072], 17/10 [3074], 22/14 [3078] and 24/14 [3079] mm); Gilimanuk ; 08°10.259´ S, 114°26.606´ E; 3 Apr. 2014; station 155; from high intertidal with water pools and many mounds up to shore with sand and rocks; UMIZ 0 0 155GoogleMaps  2 spec. (22/10 [3118] and 37/20 [3120] mm); Gilimanuk ; 08°10.156´ S, 114°26.652´ E; 4 Apr. 2014; station 156; muddy mangrove with Rhizophora  and Avicennia  trees; UMIZ 0 0 156.GoogleMaps  Timor • 2 spec. (12/7 [5890] and 15/7 [5891] mm); Oesapa ; 10°08.732´ S, 123°38.096´ E; 11 Jul. 2016; station 250 ; sandy part of mangrove, with Sonneratia  and Avicennia  ; UMIZ 0 0 157.GoogleMaps  Halmahera • 2 spec. (24/16 [5072] and 32/23 [5073] mm); Dodinga ; 00°51.348´ N, 127°38.504´ E; 9 Mar. 2015; station 206 ; back of mangrove, high intertidal, with ferns and mounds; UMIZ 0 0 158GoogleMaps  1 spec. (35/22 [5145] mm); Gamkonora ; 01°26.911´ N, 127°31.625´ E; 21 Mar. 2015; station 219; mostly Rhizophora  , with some sandy and open muddy areas; UMIZ 0 0 159.GoogleMaps  Ambon • 1 spec. (12/7 [3555] mm); Wai ; 03°34.652´ S, 128°19.526´ E; 15 Feb. 2014; station 132 ; narrow band of old Avicennia  trees on sandy mud, with old logs; UMIZ 0 0 160GoogleMaps  .

PHILIPPINES – Luzon • 2 spec. (22/15 [3221] and 20/16 [6049] mm); Calantagan , Batangas; 13°53.278´ N, 120°37.124´ E; 8 Jul. 2014; station 184; narrow forest on the shore, with Avicennia  and young Rhizophora  ; PNM 0 41272GoogleMaps  1 spec. (28/20 [3232] mm); same data as for holotype; PNM 0 41273GoogleMaps  .

Color and morphology of live animals ( Figs 45–46View FigView Fig)

Live animals are most often covered with mud, in which case their dorsal color can hardly be seen. The background of the dorsal notum is gray-brown, mottled with darker and lighter areas. In addition, in some animals, the tip of dorsal papillae (with and without dorsal eyes) can be lighter (pale yellow or white). The foot and the hyponotum are dark or light gray. The color of both the foot and the hyponotum of an individual can change rapidly, especially when disturbed. The ocular tentacles are gray-brown and may or may not be speckled with white dots, like the head. The ocular tentacles are short (just a few millimeters long). The tip of dorsal papillae is usually white or pale yellow, but not always (in any case generally covered with mud).

Digestive system ( Figs 47AView Fig, 48AView Fig, 49–50View FigView Fig)

Radulae measure up to 2.6 mm (unit #1) and 2.2 mm (unit #2) in length. Examples of radular formulae are presented in Table 4.

Reproductive system ( Figs 47View Fig B–C, 48B–C)

The male anterior organs consist of the penial complex (penis, penial sheath, vestibule, deferent duct, retractor muscle). An accessory penial gland is absent. The penial sheath is narrow and elongated. In unit #1, the retractor muscle is very short (much shorter than the penial sheath), inserting on the body wall near the nervous system, or vestigial (its distal end being free in the visceral cavity, with no clear insertion). In unit #2, the retractor muscle is long (as long as the penial sheath), inserting near the heart. The deferent duct is also highly convoluted, with many loops. Inside the penial sheath, the penis is a narrow, elongated, soft, smooth (no hooks) and hollow tube of approximately 200 μm in diameter.

Distinctive diagnostic features

Externally, Paromoionchis goslineri  gen. et sp. nov. cannot be distinguished from other species of Paromoionchis  gen. nov. The ventral side (foot and hyponotum) is gray, i.e., never yellow or orange. Unfortunately, a gray ventral side can occasionally be found in all other species of the genus, so the use of that color trait is not fully reliable for identification. However, the internal anatomy of P. goslineri  gen. et sp. nov. (no accessory penial gland, thin penis with no hooks) is very distinctive and can be used for a fully reliable identification. The only other species of Paromoionchis  gen. nov. without an accessory penial gland, P. penangensis  gen. et sp. nov., differs greatly from P. goslineri  gen. et sp. nov. anatomically because its penis is very large. Units #1 and #2 of P. goslineri  gen. et sp. nov. differ slightly with respect to the penial retractor: it is short and thin, inserting near the nervous system, or even vestigial in unit #1, while it is as long as the penial sheath, inserting near the heart in unit #2. However, given that only four specimens could be dissected in unit #1, it is very possible that intermediates may be found in the future, especially considering that units #1 and #2 are widely distant geographically.

Distribution ( Fig. 6View Fig)

Philippines (unit #1): Luzon (type locality). Indonesia (unit #2): Ambon, Bali, Halmahera, Sulawesi and Timor.

Habitat ( Fig. 51View Fig)

Paromoionchis goslineri  gen. et sp. nov. unit #1 is found on mud, in Avicennia  forests near the shore and is rare (only four specimens are known from two stations). Unit #2 is found on soft and hard mud, in mangroves or in open areas near mangroves and is rare (except in Bali, where several specimens were found at a few stations).


Philippine National Museum