Paromoionchis boholensis 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 : 50-59

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

urn:lsid:zoobank.org:act:104C35EF-FBF9-4EC2-A5A8-89AC30009270 Figs 31–40

Etymology

Paromoionchis boholensis gen. et sp. nov. is named after Bohol Island, where the type locality is.

Material examined

Holotype

PHILIPPINES • holotype (28/18 [3288] 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.

Other material

INDONESIA – Sulawesi •2spec.(35/22[2128]and37/20[2129]mm); 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 0 141 • 1 spec. (9/6 [2175] 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 0 142 • 1 spec. (20/13 [2199] mm); Tamperong ; 01°41.513´N, 125°00.797´E; 12 Mar. 2013; station 87; muddy mangrove with small and dense Rhizophora ; UMIZ 0 0 143 • 1 spec. (12/8 [2316] 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 0 144 • 1 spec. (20/13 [2360] 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. – Ambon • 3 spec. (40/25 [2849], 45/30 [2850] and 45/25 [2851] 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 . – Seram • 1 spec. (45/28 [2884] 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 . – Kei Islands • 2 spec. (10/8 [2896] and 17/8 [2901] 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 0 148 • 2 spec. (15/10 [2903] and 18/8 [2911] 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 0 149 • 3 spec. (40/22 [3565], 30/20 [2935] and 40/22 [2937] mm); Fiditan ; 05°35.957´S, 132°45.112´E; 28 Feb. 2014; station 144 ; rocks behind muddy Rhizophora mangrove; UMIZ 0 0 150 . – Bali • 1 spec. (35/17 [3117] 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. – Halmahera • 1 spec. (25/16 [5019] 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 0 151 • 2 spec. (47/30 [5140] and 35/22 [5146] 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 0 152 .

PHILIPPINES – Luzon • 1 spec. (25/18 [3609] 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 41267 . – Bohol • 2 spec. (16/9 [3283] and 17/10 [3619] mm); same data as for holotype; PNM 0 41268 • 3 spec. (20/15 [3369], 35/18 [3372] and 27/20 [3411] 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 41269 • 5 spec. (30/22 [3412], 30/23 [3413], 40/17 [3417], 40/20 [3422] and 42/25 [3423] 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 41270 .

Color and morphology of live animals ( Figs 31–32 )

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).

Digestive system ( Figs 33A , 34A , 35–36 )

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 33 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 ([3288] PNM 0 41266, holotype) to 1.2 mm ([3372] PNM 041269) in unit #1 and from 1.1 mm ([5019] UMIZ 00151) and 1.3 mm ([3117] UMIZ 00140) to 1.8 mm ([2911] UMIZ 0 0 149, [5140] UMIZ 00152) in unit #2, and its shape does vary between individuals ( Fig. 38 ). 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. 6 ), 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. 6 )

Philippines (unit #1): Bohol (type locality), Luzon. Indonesia (unit #2): Ambon, Bali, Halmahera, Kei Islands, Seram, Sulawesi.

Habitat ( Figs 39–40 )

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).

Figures

Fig. 31. Paromoionchis boholensis gen. et sp. nov., unit #1, live animals. A. Holotype, dorsal view, 28 mm long [3288], Philippines, Bohol (PNM 041266). B. Dorsal view, 26 mm long [3609], Philippines, Luzon (PNM 041267). C. Dorsal view, 38 mm long [3417], Philippines, Bohol (PNM 041270). D. Dorsal view, 17 mm long [3283], Philippines, Bohol (PNM 041268). E. Dorsal view, 30 mm long [3372], Philippines, Bohol (PNM 041269). F. Dorsal view, 17 mm long [3619], Philippines, Bohol (PNM 041268). G. Ventral view, same as E. H. Ventral view, 38 mm long [3422], Philippines, Bohol (PNM 041270). I. Ventral view, 32 mm long [3413], Philippines, Bohol (PNM 041270). J. Ventral view, same as C.

Fig. 32. Paromoionchis boholensis gen. et sp. nov., unit #2, live animals. A. Dorsal view, 37 mm long [2129], Indonesia, Sulawesi (UMIZ 00141). B. Dorsal view, 45 mm long [2851], Indonesia, Ambon (UMIZ 00146). C. Dorsal view, 35 mm long [3117], Indonesia, Bali (UMIZ 00140). D. Dorsal view, 18 mm long [2911], Indonesia, Kei (UMIZ 00149). E. Dorsal view, 40 mm long [2937], Indonesia, Kei (UMIZ 00150). F. Dorsal view, 15 mm long [2903], Indonesia, Kei (UMIZ 00149). G. Ventral view, 45 mm long [2884], Indonesia, Seram (UMIZ 00147). H. Ventral view, same as B. I. Ventral view, 45 mm long [2850], Indonesia, Ambon (UMIZ 00146). J. Frontal view, 17 mm long [2901], Indonesia, Kei (UMIZ 00148).

Fig. 33. Paromoionchis boholensis gen. et sp. nov., unit #1, holotype, Philippines, Bohol [3288] (PNM 041266). A. Digestive system. B. Posterior hermaphroditic (female) reproductive system. C. Male copulatory organs. Abbreviations: ag = accessory penial gland; dd = deferent duct; ddg = dorsal lobe of digestive gland; fgm = female gland mass; hd = hermaphroditic duct; hg = hermaphroditic gland; i = intestine; ms = muscular sac (of accessory penial gland); ov = oviduct; pdg = posterior lobe of digestive gland; ps = penial sheath; r = rectum; rm = retractor muscle; rs = receptaculum seminis; sp = spermatheca; st = stomach; v = vestibule. Scales = 2 mm.

Fig. 34. Paromoionchis boholensis gen. et sp. nov., unit #2, Indonesia, Bali [3117] (UMIZ 00140). A. Digestive system. B. Posterior hermaphroditic (female) reproductive system. C. Male copulatory organs. Abbreviations: ag = accessory penial gland; dd = deferent duct; ddg = dorsal lobe of digestive gland; fgm = female gland mass; hd = hermaphroditic duct; hg = hermaphroditic gland; i = intestine; ms = muscular sac (of accessory penial gland); ov = oviduct; pdg = posterior lobe of digestive gland; ps = penial sheath; r = rectum; rm = retractor muscle; rs = receptaculum seminis; sp = spermatheca; st = stomach; v = vestibule. Scales: A–B = 2 mm; C = 3 mm.

Fig. 35. Paromoionchis boholensis gen. et sp. nov., unit #1, radula, Philippines, Bohol [3372] (PNM 041269). A. Rachidian and innermost lateral teeth. B. Lateral teeth with rachidian teeth. C. Lateral teeth. D. Outermost lateral teeth. Scales: A = 20 μm; B, D = 30 μm; C = 50 μm.

Fig. 36. Paromoionchis boholensis gen. et sp. nov., unit #2, radula, Indonesia, Ambon [2851] (UMIZ 00146). A. Rachidian and innermost lateral teeth. B. Lateral teeth with rachidian teeth. C. Lateral teeth. D. Outermost lateral teeth. Scales: A, D = 30 μm; B–C = 50 μm.

Fig. 37. Paromoionchis boholensis gen. et sp. nov., unit #1, spine of accessory penial gland. A. Holotype, Philippines, Bohol [3288] (PNM 041266). B. Philippines, Bohol [3372] (PNM 041269). C. Distal tip of spine, same as B. Scales: A–B = 100 μm; C = 10 μm.

Fig. 38. Paromoionchis boholensis gen. et sp. nov., unit #2, spine of accessory penial gland. A. Indonesia, Bali [3117] (UMIZ 00140). B. Indonesia, Kei [2911] (UMIZ 00149). C. Tip of spine, Indonesia, Ambon [2851] (UMIZ 00146). D. Distal tip of spine, same as B. E. Tip of spine, same as A. F. Tip of spine, Indonesia, Halmahera [5140] (UMIZ 00152). Scales: A–B = 200 μm; C–F = 30 μm.

Fig. 39. Paromoionchis boholensis gen. et sp. nov., unit #1, habitats. A. Philippines, Bohol, Maribojoc, large porous rocks behind mangrove (station 193, type locality). B. Philippines, Bohol, Mabini, open Avicennia and Sonneratia forest with large gravel of coral pieces, sand and algae on surface (station 196). C. Philippines, Bohol, Maribojoc, uplifted, dead coral flat covered with sand and algae adjacent to a few mangrove trees (station 202).

Fig. 40. Paromoionchis boholensis gen. et sp. nov., unit #2, habitats. A. Indonesia, Bali, muddy mangrove with Rhizophora and Avicennia trees (station 156). B. Indonesia, Sulawesi, sand, small rocks and pieces of wood outside a narrow coastal mangrove (station 88). C. Indonesia, Ambon, narrow band of old Avicennia trees on sandy mud, with old logs on ground (station 132). D. Indonesia, Kei, back of mangrove with rocks, mud, logs and leaf litter (station 140). E. Indonesia, Halmahera, mostly Rhizophora, with some sandy areas and some open 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.).