Bornella hermanni Angas, 1864

Pola, Marta, Rudman, William B. & Gosliner, Terrence M., 2009, Systematics and preliminary phylogeny of Bornellidae (Mollusca: Nudibranchia: Dendronotina) based on morphological characters with description of four new species, Zootaxa 1975, pp. 1-57 : 17-22

publication ID	https://doi.org/ 10.5281/zenodo.185130
DOI	https://doi.org/10.5281/zenodo.5689399
persistent identifier	https://treatment.plazi.org/id/03F98793-FF84-7225-2BCF-FF4FA105F856
treatment provided by	Plazi
scientific name	Bornella hermanni Angas, 1864
status

Treatment

Bornella hermanni Angas, 1864 View in CoL

( Figures 4C View FIGURE 4. A – E , 6–11 View FIGURE 6 View FIGURE 7 View FIGURE 8 View FIGURE 9 View FIGURE 10 View FIGURE 11 )

Bornella hermanni Angas, 1864: 61 View in CoL –62, Pl. VI, fig. 1.

Bornella japonica Baba, 1949: 88 View in CoL –89, 168, Text-fig. 111, Pl. 35, fig. 129. syn. nov.

Material examined: Australia: AM C. 152056, Australia, New South Wales, off Port Stephens, 4 km E. of South Head, Boondelbah Island, 32°42.530’S, 152° 13.650E’, one specimen 13 mm preserved, dissected, December 1986, coll: J. W. Ellis. AM C. 108069, Australia, New South Wales, Sydney, Bondi, 33°53.500’S, 151° 17.000E’, intertidal on wharf piles, five specimens (two dissected) about 7 and 12 mm preserved, October 1977, coll: Kuiter & Reynolds. AM C. 126475, Australia, New South Wales, Jervis Bay, Summer Cloud Bay, 35°10.410’S, 150°41.280’E, one specimen 11 mm preserved, dissected, January 1981, coll: J. Wyche. AM C. 112212, Australia, New South Wales, Jervis Bay, Callala Point, 35°500’S, 150°43.350’E, under rocks, sheltered rock platform, three specimens 10-15 mm preserved, 18 October 1978. AM C. 113793, Australia, New South Wales, Sydney, N. Collaroy Long Reef, 33°44.600’S, 151°18.600’E, one specimen 10 mm preserved, dissected, 2 December 1978, coll: I. Loch. AM C. 151993, Australia, New South Wales, Sydney, N. Bungan Head, 33°40.000’S, 151°19.400’E, rock platform, LSW, one specimen 13 mm preserved, 2 November 1986, coll: I. Loch. AM C. 138000, Australia, New South Wales, Twofold Bay, Brierly Point, intertidal, one specimen 10 mm preserved, dissected, 26 February 1983, coll: W.B. Rudman. Japan: NSMT-Op R: 38, syntype, Japan, Sagami Bay, Hayama, Isshiki, shallow water, adult specimen 22 mm preserved, 8 August 1929, coll: Baba. NSMT-Op R: 32, syntype, Japan, Sagami Bay, Hayama, Najima, 9 to 11 fathoms, adult specimen 40 mm preserved, described and partially dissected by K. Baba, 1949, full dissected in this paper, 26 June 1929. CASIZ 174980, Japan, Okinawa, Seragaki, 1.3 km E.N.E of Maeki-zaki, 69 m depth, one immature specimen 28 mm alive (18 mm preserved), 1 March 1997, coll: R. Bolland. CASIZ 174986, Japan, Okinawa, Horseshoe Cliffs, 59 m depth, one specimen 15 mm alive (10 mm preserved), 29 March 1997, coll: R. Bolland. Malaysia: CASIZ 175745, Malaysia, Pulau Tenggol, north point, one specimen 9 mm preserved, dissected, 15 m depth, 30 September 2007, coll: T.M. Gosliner. CASIZ 175744, Malaysia, Tokong Kamundi, one specimen 7 mm preserved, 14 m depth, 29 September 2007, coll: T.M. Gosliner. CASIZ 175743, Malaysia, Pulau Tenggol, north Point, one specimen 5 mm preserved, dissected, 21 m depth, 29 September 2007, coll: T.M. Gosliner. Indian Ocean: AM C. 127467, Indian Ocean, Christmas Island, 10°26’S, 105°40’7E, 7 m depth, one specimen 7 mm alive, 21 February 1981, coll: C. Tong. CASIZ 175404, Marshall Island, Oceanside Ennubuj-Ennylabegan reef, Kwajalein Atoll, on hydroid on bottom of surge channel at night, one specimen 15 mm alive, dissected, 15 m depth, 15 April 2007, coll: S. Johnson.

Geographic Distribution: Originally described from eastern Australia ( Angas 1864) it has been reported from Japan under the synonym B. japonica ( Baba 1949; Okutani 2000; Nakano 2001; Nishina 2001a, b; Masayoshi 2002). It has also been found in the Marshall Islands ( Johnson 2007; present study), Indian Ocean, Malaysia (present study) and Korea ( Koh 2006).

External morphology: The general body shape is elongate and limaciform with the posterior end of the foot being long and tapering. The living adults are up to 50 mm in length. The animal is translucent creamwhite with a network of red-orange broken lines on the back and both sides of the body and scattered subepidermal opaque white granules. This color pattern may extend to the stalk of the rhinophore sheaths and the dorsolateral processes. Most of the specimens examined in this study are shown in Figure 6 View FIGURE 6 in order to show its external variability. Figure 6 View FIGURE 6 A shows the original painting from Angas (1964). The lobe-like oral tentacle papillae, the branches of the rhinophore sheaths and the dorsolateral processes are white, sometimes with some yellow-orange pigmentation. The head is rounded, bearing on either side of the mouth an oral lobe, each consisting in 13–14 finger-like papillae of unequal length arranged in three different rows. The smaller specimens bear usually 9 to 12 papillae. The rhinophore sheaths are tall and the rhinophore, at the tip of each sheath, bears between 15 to 20 lamellae. At the upper edge of each sheath are three long and narrow anterior and anterolateral papillae and a taller, posterior sail-like papilla, which bears two or three secondary papillae. Behind the rhinophores there are three pairs of dorsolateral processes, followed by two unpaired processes in the dorsal midline. The number of processes was consistent in all specimen examined, except for one specimen, which had a forth small pair ( Fig. 7 View FIGURE 7 B). The first and second pair of the dorsolateral processes has three or four branches, one larger at the center (which can be bifurcate) and two smaller laterals. The third pair of processes usually has three branches. In those paired dorsolateral processes with four branches, there are three tripinnate translucent gills located on the inner surface, at the junction of each lateral papilla with the middle one. In those paired dorsolateral processes with three branches, there are only two gills. The two posterior, single, dorsal processes are simple and decrease in size towards the tail. The anus is located on the right side of the dorsum between the first and second pair of dorsolateral processes, closer to the second. The reproductive opening is located on the right side, midway between the rhinophore sheath and the first dorsolateral process.

Alimentary Canal: The buccal bulb is relatively large. The labial cuticle is thick, with a labial armature of irregular, cuticular rodlets surrounding the opening from the oral tube into the buccal bulb. The rodlets are elongate and numerous ( Fig. 8 View FIGURE 8 A). The jaws are roughly oval in shape, without a distinct masticatory process ( Fig. 8 View FIGURE 8 B). The radular formula of the syntype of B. hermanni is 35 x 14.1.14 (NSMT-Op R: 32, 40 mm preserved). Other specimens dissected have the formulae: 28 x 11.1.11 (CASIZ 174980, 18 mm preserved; CASIZ 174986, 10 mm preserved), 25 x 11 – 12.1.11 –12 (CASIZ 175404, 15 mm alive), 22 x 10.1.10 and 15 x 11.1.11 (AM C. 108069, 7 and 12 mm preserved), 23 x 10.1.10 (AM C. 126475, 11 mm preserved), 22 x 8 –10.1.8–10 (CASIZ 175745, 9 mm preserved), 22 x 7 –8.1.7–8 (AM C. 152056, 13 mm preserved), 22– 23 x 8–9.1.1.8–9 (AM C. 112212, 15 mm preserved; AM C. 113793, 10 mm preserved), 24 x 7.1.7 (AM C. 127467, 7 mm alive). The rachidian teeth are variable ( Figs. 8 View FIGURE 8 C,D; 9,10), usually wider than taller, with about eight to ten denticles on either side of a median cusp. Nevertheless, in some specimens the rachidian teeth are more elongate and the cusp is more prominent than those described from the syntype of B. hermanni , with fewer denticles on each side of the cusp ( Figs. 9 View FIGURE 9 , 10 View FIGURE 10 ). Most of the laterals have a long basal portion and then straighten or with a slightly smooth-edge hook, which terminate in a fine point, increasing in size from the innermost outwards. The penultimate (or antepenultimate) lateral is usually a denticle with a short cusp followed by from one to two plate-like laterals ( Figs. 8 View FIGURE 8 C,D). A long unpaired oral gland is found ventrally. It extends back from the ventral midline side of the mouth to the region of the reproductive system. The paired, compact branched, salivary glands are yellowish in preservative, and attached along the sides of the oesophagus. They open into the posterior buccal bulb on each side of the oesophageal opening. The oesophagus is relatively short and wide, passing into the oval thin walled stomach. The two anterior digestive glands open on the upper surface of the stomach. These two glands are about the same size and have two lobes, the lower going into the dorsolateral process and the upper into the rhinophore sheath on their side of the body. The posterior portion of the digestive gland opens on the lower left surface of the stomach. All pairs of dorsolateral processes, behind the first pair, receive branches from the posterior portion of the digestive gland. The posterior stomach is armed with about 20 to 30 longitudinal rows of chitinous brown spines ( Figs. 11 View FIGURE 11 A-C). These spines are straight, cylindrical, and spatuliform at the tip. The spines decrease in size posteriorly. From here the intestine descends to the ventral side and then bends dorsally to the anus.

Reproductive system: ( Fig. 4C View FIGURE 4. A – E ): The ovotestis usually consists of about four rounded follicles lying over the posterior digestive gland, although the number varies from three to eight in the studied specimens. From each of these lobes a thin-walled duct arises which join to form a common hermaphroditic duct, which expands to form the large swollen ampulla. The hermaphroditic duct runs around the stomach on the left side, between the stomach and the posterior branch of the digestive gland. The ampulla lies on the dorsal side of the female gland mass. The ampulla then narrows before dividing into separate male and female ducts, the vas deferens and the oviduct respectively. Only a short section of the oviduct is visible before it enters the female gland mass. The vas deferens is relatively long and coiled, and seems to be enclosed in a layer of prostate gland along it whole length. It leads to the penial bulb, which contains a fleshy, irregularly lobed structure, which is armed with a single circular row of chitinous hooked spines ( Masayoshi 2002). The spines are relatively large and each is inserted into it own raised fleshy base ( Figs. 11 View FIGURE 11 D–F). A stalked distal allosperm receptacle opens alongside the vaginal opening.

Remarks: Baba (1949) described Bornella japonica from Japan and in his description he notes that its size and color is similar to that of Bornella stellifer but that it is easily distinguished by the following characters: Rhinophore sheaths with four supra-marginal papillae, the hindmost and largest subdivided into twothree smaller papillae (in B. stellifer the supra-marginal papillae are simple); dorsolateral processes in three pairs (five-six pairs in B. stellifer ); three gills on the first and second, and two or three on the last processes (one gill per process in B. stellifer ). However Angas (1864) described and illustrated Bornella hermanni from Sydney Harbour, in eastern Australia, which clearly shows the three pairs of dorsolateral processes, which are one of the characters differentiating this species from B. stellifer . Although the published color painting ( Angas, 1864: Pl VI, fig. 1) does not show the color pattern clearly, the original watercolor is in the collections of the Australian Museum Library ( Fig. 6 View FIGURE 6 A). Angas was a skilled and accurate artist and in the original painting the color pattern of white specks, broken orange lines, white papillae and lack of orange rings on the dorsolateral papillae, are accurately recorded. Bornella hermanni is not uncommonly found in central and southern New South Wales.

This species has been misidentified as B. stellifer in several field guides ( Debelius 1998; Koh 2006) and web pages ( Imamoto 2008; Masayoshi 2002). In summary, B. hermanni can be distinguished from B. stellifer in many different ways, including the shape of the posterior sail of the rhinophore sheaths and the dorsolateral processes - in B. hermanni they are always branched while in B. stellifer they are simple, rounded papillae. Bornella hermanni also lacks the orange-red subapical ring on the papillae, being cream-white in color. Internally, both species have several differences. In B. stellifer the buccal bulb is small, while in B. hermanni it is much larger and the spines in the posterior stomach are acutely pointed and less numerous in B. stellifer while in B. hermanni they are more numerous and spatuliform in shape. In the reproductive system, the penial spines of B. hermanni are arranged in a single ring on large fleshy lobe while in B. stellifer they are arranged in several rows around the penial opening. The reproductive system of this species had not been previously described.