Paromoionchis boholensis 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: 50-59
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|Paromoionchis boholensis Dayrat & Goulding|
gen. et sp. nov.
Paromoionchis boholensis Dayrat & Goulding gen. et sp. nov.
Paromoionchis boholensis gen. et sp. nov. is named after Bohol Island, where the type locality is.
PHILIPPINES • holotype (28/18  mm); Bohol, Maribojoc ; 09°43.645´ N, 123°50.988´ E; 15 Jul. 2014; station 193; small island at end of boardwalk, sandy mud and rocks in back of mangrove; PNM 0 41266.GoogleMaps
INDONESIA – Sulawesi •2spec.(35/22and37/20mm); Wori ; 01°36.055´N, 124°51.730´E; 9 Mar. 2013; station 84; tall mangrove forest of Sonneratia and Avicennia , with old logs; UMIZ 0 0 141GoogleMaps • 1 spec. (9/6  mm); Bahoi ; 01°43.355´ N, 125°01.232´ E; 10 Mar. 2013; station 85; sand, small rocks and pieces of wood, near narrow coastal mangrove; UMIZ 0 0 142GoogleMaps • 1 spec. (20/13  mm); Tamperong ; 01°41.513´ N, 125°00.797´ E; 12 Mar. 2013; station 87; muddy mangrove with small and dense Rhizophora ; UMIZ 0 0 143GoogleMaps • 1 spec. (12/8  mm); Mantehang ; 01°41.880´ N, 124°46.741´ E; 15 Mar. 2013; station 91; Sonneratia at low intertidal and Rhizophora at high intertidal; UMIZ 0 0 144GoogleMaps • 1 spec. (20/13  mm); Panikkiang Island; 04°21.730´ S, 119°35.630´ E; 25 Mar. 2013; station 94; Rhizophora , Avicennia , Sonneratia and old logs; UMIZ 0 0 145.GoogleMaps – Ambon • 3 spec. (40/25 , 45/30  and 45/25  mm); Wai; 03°34.652´ S, 128°19.526´ E; 15 Feb. 2014; station 132 ; narrow band of old Avicennia trees on sandy mud, old logs on ground; UMIZ 0 0 146.GoogleMaps – Seram • 1 spec. (45/28  mm); Piru; 03°04.072´ S, 128°11.362´ E; 19 Feb. 2014; station 136 ; Sonneratia mangrove next to fish market, next to beach of palms and ferns, with cattle roaming around; UMIZ 0 0 147.GoogleMaps – Kei Islands • 2 spec. (10/8  and 17/8  mm); Un ; 05°38.273´ S, 132°45.738´ E; 23 Feb. 2014; station 137 ; Bruguiera and Rhizophora , some muddy areas and some with coral rubble; UMIZ 0 0 148GoogleMaps • 2 spec. (15/10  and 18/8  mm); Un ; 05°38.273´ S, 132°45.738´ E; 25 Feb. 2014; station 140 ; back of mangrove, on rocks, on mud, inside logs and under leaf litter; UMIZ 0 0 149GoogleMaps • 3 spec. (40/22 , 30/20  and 40/22  mm); Fiditan ; 05°35.957´ S, 132°45.112´ E; 28 Feb. 2014; station 144 ; rocks behind muddy Rhizophora mangrove; UMIZ 0 0 150GoogleMaps . – Bali • 1 spec. (35/17  mm); Gilimanuk; 08°10.156´ S, 114°26.652´ E; 4 Apr. 2014; station 156; muddy mangrove with Rhizophora and Avicennia trees; UMIZ 0 0 140.GoogleMaps – Halmahera • 1 spec. (25/16  mm); Sofifi ; 00°45.473´ N, 127°35.897´ E; 8 Mar. 2015; station 205; Sonneratia mangrove, with dense roots and hard mud; UMIZ 0 0 151GoogleMaps • 2 spec. (47/30  and 35/22  mm); Gamkonora ; 01°26.911´ N, 127°31.625´ E; 21 Mar. 2015; station 219; mostly Rhizophora mangrove with some sandy areas and some open muddy spaces; UMIZ 0 0 152GoogleMaps .
PHILIPPINES – Luzon • 1 spec. (25/18  mm); Lian , Batangas; 13°58.130´ N, 120°37.471´ E; 5 Jul. 2014; station 179; narrow and impacted mangrove of Avicennia near village, very sandy, little to no mud; PNM 0 41267GoogleMaps . – Bohol • 2 spec. (16/9  and 17/10  mm); same data as for holotype; PNM 0 41268GoogleMaps • 3 spec. (20/15 , 35/18  and 27/20  mm); Mabini ; 09°51.586´ N, 124°34.155´ E; 18 Jul. 2014; station 196; open Avicennia and Sonneratia forest with sand, algae and coral rubble; PNM 0 41269GoogleMaps • 5 spec. (30/22 , 30/23 , 40/17 , 40/20  and 42/25  mm); Maribojoc ; 09°44.280´ N, 123°49.389´ E; 20 Jul. 2014; station 202; uplifted coral rubble with sand and algae, near Sonneratia trees; PNM 0 41270GoogleMaps .
Live animals are often covered with mud, in which case their dorsal color can hardly be seen. In unit #1, the background of the dorsal notum is brown, occasionally mottled with darker or lighter areas, while in unit #2 it ranges from very light brown (almost white) to dark brown, mottled or not. In some animals, there is a reddish hue on the margin of the dorsal notum (unit #1). In addition, in most animals the tip of the dorsal papillae (with and without dorsal eyes) can be bright yellow. The foot is orange (unit #1) or varies from gray to yellow and orange (unit #2). The hyponotum is also orange, often with a darker ring on the margin which may be bright red (unit #1) or homogenously gray, yellow, or orange, but can also display a mix of two or three of those colors (unit #2). The color of both the foot and the hyponotum of an individual can change very rapidly, especially when disturbed. The ocular tentacles are reddish brown and may or may not be speckled with white dots, like the head. The ocular tentacles are short (just a few millimeters long).
Radulae measure up to 4.5 mm (unit #1) and 4 mm (unit #2) in length. Examples of radular formulae are presented in Table 4.
Reproductive system ( Figs 33View Fig B–C, 34B–C, 37–38)
The male anterior organs consist of the penial complex (penis, penial sheath, vestibule, deferent duct, retractor muscle) and the accessory penial gland (flagellum and hollow spine). The hollow spine of the accessory penial gland is narrow, elongated, slightly curved. Its base is conical. Its diameter is approximately 50 to 70 μm for most of its length and 100–130 μm at its base (unit #1) and approximately 70 to 80 μm for most of its length and 150–200 μm at its base (unit #2). Its length ranges from 1 mm ( PNM 0 41266, holotype) to 1.2 mm ( PNM 041269) in unit #1 and from 1.1 mm ( UMIZ 00151) and 1.3 mm ( UMIZ 00140) to 1.8 mm ( UMIZ 0 0 149,  UMIZ 00152) in unit #2, and its shape does vary between individuals ( Fig. 38View Fig). The penial sheath is narrow and elongated. The retractor muscle is vestigial, i.e., with its distal end being free in the visceral cavity, with no clear insertion (unit #1), or absent or vestigial (unit #2). The deferent duct is 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, the color of the foot and hyponotum can help one to identify Paromoionchis boholensis gen. et sp. nov., but unfortunately it is not fully reliable. Specimens with a bright orange foot and hyponotum are only found in P. boholensis gen. et sp. nov., especially in unit #1 but also in unit #2; the ventral side of P. tumidus , which is sympatric with P. boholensis ( Fig. 6View Fig), can be orange but not bright orange. However, specimens with a more yellowish or greyish foot and hyponotum cannot be identified externally. The internal anatomy of P. boholensis gen. et sp. nov. (accessory penial gland, vestigial penial retractor muscle, penis with no hooks) is similar to that of P. daemelii . However, P. boholensis gen. et sp. nov. and P. daemelii do not overlap geographically, at least based on the present data. Thus, within its distribution range P. boholensis gen. et sp. nov. is the only species with this combination of internal characters. Indeed, the internal characters of the two species of Paromoionchis gen. nov. with which P. boholensis gen. et sp. nov. is sympatric ( P. goslineri gen. et sp. nov. and P. tumidus ) are different ( Table 3). It must be noted that the known distribution of species of Paromoionchis gen. nov. may change as new records are found in the future and so the use of geographic data should only be used with caution for identification.
Distribution ( Fig. 6View Fig)
Philippines (unit #1): Bohol (type locality), Luzon. Indonesia (unit #2): Ambon, Bali, Halmahera, Kei Islands, Seram, Sulawesi.
Unit #1 of Paromoionchis boholensis gen. et sp. nov. is found on sandy mud or sand with very little mud, in mangroves or near mangrove trees and is rare (it was found at only four stations). Unit #2 is found in open or dense mangroves, on soft or hard mud, as well as on muddy sand and is common (but not as common as P. tumidus unit #1).
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