Paromoionchis goslineri Dayrat & Goulding, 2019

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

Paromoionchis goslineri Dayrat & Goulding gen. et sp. nov.

urn:lsid:zoobank.org:act:E375A628-4AE6-4E10-B424-D4BBF58F8941 Figs 45–51

Etymology

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

Holotype

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.

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 0 161 • 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 0 153 . – 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 0 154 • 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 0 155 • 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. – 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 . – 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 0 158 • 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. – 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 0 160 .

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 41272 • 1 spec. (28/20 [3232] mm); same data as for holotype; PNM 0 41273 .

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

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 47A , 48A , 49–50 )

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 47 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. 6 )

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

Habitat ( Fig. 51 )

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).

Figures

Fig. 45. Paromoionchis goslineri gen. et sp. nov. unit #1, live animals, Philippines, Luzon. A. Dorsal view, 30 mm long [3232] (PNM 041273). B. Dorsal view, 22 mm long [3221] (PNM 041272). C. Holotype, dorsal view, 25 mm long [3233] (PNM 041271). D. Ventral view, same as B. E. Ventral view, same as A.

Fig. 46. Paromoionchis goslineri gen. et sp. nov. unit #2, live animals. A. Dorsal view, 33 mm long [3120], Indonesia, Bali (UMIZ 00156). B. Dorsal view, 32 mm long [5073], Indonesia, Halmahera (UMIZ 00158). C. Dorsal and ventral views, 18 mm long [2241], Indonesia, Sulawesi (UMIZ 00153). D. Dorsal view, 24 mm long [3079], Indonesia, Bali (UMIZ 00155). E. Ventral view, 26 mm long [5072], Indonesia, Halmahera (UMIZ 00158). F. Ventral view, 16 mm long [5891], Indonesia, Timor (UMIZ 00157) G. Ventral view, 26 mm long [3066], Indonesia, Bali (UMIZ 00154).

Fig. 47. Paromoionchis goslineri gen. et sp. nov. unit #1, holotype, Philippines, Luzon [3233] (PNM 041271). A. Digestive system. B. Posterior hermaphroditic (female) reproductive system. C. Male copulatory organs. Abbreviations: dd = deferent duct; ddg = dorsal lobe of digestive gland; fgm = female gland mass; hd = hermaphroditic duct; hg = hermaphroditic gland; i = intestine; ov = oviduct; pdg = posterior lobe of digestive gland; ps = penial sheath; r = rectum; rm = retractor muscle; rs = receptaculum seminis; sp = spermatheca; st = stomach. Scales: A–B = 2 mm; C = 1 mm.

Fig. 48. Paromoionchis goslineri gen. et sp. nov. unit #2, Indonesia, Sulawesi [2241] (UMIZ 00153). A. Digestive system. B. Posterior hermaphroditic (female) reproductive system. C. Male copulatory organs. Abbreviations: dd = deferent duct; ddg = dorsal lobe of digestive gland; fgm = female gland mass; hd = hermaphroditic duct; hg = hermaphroditic gland; i = intestine; ov = oviduct; pdg = posterior lobe of digestive gland; ps = penial sheath; r = rectum; rm = retractor muscle; rs = receptaculum seminis; sp = spermatheca; st = stomach. Scales: A = 2 mm; B–C = 1 mm.

Fig. 49. Paromoionchis goslineri gen. et sp. nov. unit #1, radula, Philippines, Luzon [6049] (PNM 041272). A. Rachidian and innermost lateral teeth. B. Lateral teeth with rachidian teeth. C. Lateral teeth. D. Outermost lateral teeth. Scales: A = 20 μm; B–C = 50 μm; D = 10 μm.

Fig. 50. Paromoionchis goslineri gen. et sp. nov. unit #2, radula, Indonesia, Bali [3078] (UMIZ 00155). A. Rachidian and innermost lateral teeth. B. Lateral teeth with rachidian teeth. C. Lateral teeth. D. Outermost lateral teeth. Scales: A–B = 20 μm; C = 30 μm; D = 10 μm.

Fig. 51. Paromoionchis goslineri gen. et sp. nov., habitats. A. Philippines, Luzon, impacted mangrove next to a village, narrow band of Avicennia by the shore (station 185, type locality). B. Indonesia, Sulawesi, mostly Rhizophora, with sand, small rocks and pieces of wood outside narrow coastal mangrove (station 89). C. Indonesia, Bali, short mangrove shrubs, high intertidal, muddy area with pools (station 155). D. Indonesia, Bali, short mangrove shrubs high in intertidal, muddy area with pools (station 156). E. Indonesia, Halmahera, Rhizophora trees in open mangrove with sandy and muddy areas (station 219).

Fig. 6. Geographic distribution of the five species of Paromoionchis gen. nov. Distinct colors are used for each mitochondrial unit found in P. tumidus (Semper, 1880) comb. nov., P. boholensis gen. et sp. nov. and P. goslineri gen. et sp. nov., and the colors used for each unit are the same as those used in Figs 1–5. Colored areas correspond to hypothetical ranges proposed based on known records (all of which are new here except for the type localities of P. tumidus and P. daemelii (Semper, 1880) comb. nov.).