Kaloplocamus albopunctatus, Wei & Kong, 2023

Wei, Jingcheng & Kong, Lingfeng, 2023, Taxonomic review of Kaloplocamus from the Yellow Sea, China with the description of a new species (Nudibranchia, Doridina, Polyceridae), ZooKeys 1168, pp. 107-129 : 107

Kaloplocamus albopunctatus sp. nov.

Figs 3 , 4 , 5

Kaloplocamus ramosus : Qi et al. 1986: 63; Baba 1989: 232-234, figs 1-3; Qi et al. 1989: 119, fig. 88; Zhang et al. 2016: 207, fig. 255.

Type locality.

China, Shandong: Tianheng Town, 36°33.7′N, 120°58.6′E.

Holotype: Alcohol-fixed, original label: "CN, SD, Tianheng, 36°33.7′N, 120°58.6′E, 26 Apr. 2022, J.C. Wei" "MBM287619 ".

Paratypes: Alcohol-fixed, two specimens, original label: "CN, SD, Tianheng, 36°33.7′N, 120°58.6′E, 26 Apr. 2022, J.C. Wei" "LSGB hb266000 0302 to 0303"; alcohol-fixed, five specimens, original label: "CN, SD, Tianheng, 36°33.7′N, 120°58.6′E, 04 May. 2022, J.C. Wei" "LSGB hb266000 0304 to 0308".

Description.

External morphology (Fig. 3 ) Living animals are up to 25 mm long. The body is elongate, limaciform, bright orange, and with the whole body covered with reddish dots except the foot. These dots are especially dense in the portions around the bases of the lateral appendages and branchial leaves. The lateral portions of the body have scattered white patches composed of dots in series and are moderately transparent so that the digestive gland is visible. The mantle is rather smooth, with very few small, white tubercles on the dorsum. The oral tentacles are flat and wide. The head bears eight velar appendages, which are short, pale orange-yellow, semitranslucent with reddish dots, and the tips are a brighter orange-red color. There are clusters of short, acute ramifications on the velar appendages. The bases of these ramifications are orange-red, while the rest is cream-colored. The dorsum has four pairs of lateral appendages that are larger than the appendages on the head, also with clusters of ramifications. These dorsal appendages share almost the same shape and coloration as the velar ones except that each of the dorsal appendages bears more ramifications. The gill is situated between the second and third pair of appendages. There are five tripinnate branchial leaves and they have the same coloration as the body; the stems of the leaves are translucent and have bright orange dots. The rhinophores have a semitranslucent peduncle with small, dense, orange-yellow dots. The clavus is orange in color, with approximately 16-18 rhinophoral lamellae and with a white tip and a white line on the anterior side. The rhinophoral sheath is short and speckled with orange-yellow dots. The posterior part of the foot is elongate, acutely pointed, and red-orange, with many opaque, white, pointed tubercles that are concentrated centrally.

Radula (Fig. 4 ) The radular formula of the 23 mm specimen examined is 15 × 13.3.0.3.13. The radula is characterized by the presence of two types of well-differentiated teeth (Fig. 4A-D ). The three inner lateral teeth share a similar hook-like shape, and a secondary cusp is developed although only the outermost one has a short, less obvious cusp. The hook of the outermost lateral teeth is sharp while on the innermost two teeth, it is comparatively blunt (Fig. 4A, D ). The outer marginal teeth are roughly rectangular in shape, with long grooves on the surface (Fig. 4C ). The sizes of these teeth are equivalent except for the teeth on the very edge, which are much smaller than the others (Fig. 4B, C ). The rachis is granulated and is not transversally divided in rows (Fig. 4E ). The jaws have thin, elongate rodlets which are densely packed (Fig. 4F ).

Reproductive system (Fig. 5 ) The reproductive system is triaulic. The vas deferens is enlarged in the distal portion and differentiated into an inflated prostate which joins the bursa copulatrix via a thin duct. The vagina is rather narrow, only one-third of the length of the vas deferens, and enters directly to the oval bursa copulatrix. From the bursa copulatrix emerges a short duct that divides into a uterine duct, which connects to the oval female gland mass, and a crooked duct connecting to the receptaculum seminis. The ampulla is short, coiled, and enters into the female gland mass in a relatively distal position. The penis has spines which are elongated and of equal width (Suppl. material 2).

Egg mass (Suppl. material 3). The egg mass of this species is flat, belt-like, coiled, and translucent with white eggs within. It is so similar to the egg mass of K. japonicus that DNA was extracted after all the egg masses were photographed and the COI gene was then amplified and sequenced to distinguish the egg masses of these two species.

Etymology.

The specific epithet albopunctatus refers to the white patch on the body of this animal. The Chinese common name for this species is “白斑鬈发海牛.”

Remarks.

Kaloplocamus albopunctatus sp. nov. shows a bright orange coloration, which is rather common within Kaloplocamus . There are four other Kaloplocamus species that share a similar color pattern: K. ramosus , K. acutus , K. peludo Vallès & Gosliner, 2006, and K. maru Vallès & Gosliner, 2006 (Table 3 ). Baba (1989) described three forms of K. ramosus from Japan: the orange form A shared many similarities with K. albopunctatus sp. nov., such as the color of appendages and characters of radula. Baba (1989: 234) described this form as "Sometimes there are a few opaque white spots near the root of the dorso-lateral processes.", which is a major difference that makes K. albopunctatus sp. nov. distinct from K. ramosus . In Baba’s drawing of the reproductive system ( Baba 1989: fig. 3), the receptaculum seminis ( “c” in Baba’s drawing) is not connected to the female gland mass ( “fg” in Baba’s drawing). The receptaculum seminis of K. albopunctatus sp. nov. is connected to the female gland mass via the uterine duct. However, according to Bergh (1880) and Vallès and Gosliner (2006), it seems to be a common pattern that the receptaculum seminis of Kaloplocamus is connected to the bursa copulatrix and the female gland mass. There are many similarities between Kaloplocamus albopunctatus sp. nov. and K. ramosus , such as having the same number of ramified appendages and the same color of the body, rhinophores, and branchial leaves, which is why K. ramosus had been reported from the Yellow Sea in the past ( Qi et al. 1986, 1989; Zhang et al. 2016) despite the type locality of this species being the Mediterranean Sea. However, there are several characters that make K. albopunctatus sp. nov. distinct from K. ramosus . Firstly, K. ramosus is characterized by having small, translucent, orange tubercles on the dorsum and appendages with orange, elongated secondary ramifications, while the dorsum of K. albopunctatus sp. nov. is rather smooth and has only short simple ramifications that are cream-colored. Additionally, the vas deferens of K. albopunctatus sp. nov. is differentiated into a prostate, but K. ramosus does not have a prostate ( Vallès and Gosliner 2006). Moreover, the K. ramosus reported from the Yellow Sea were described as having "red-orange and white dots on the body, the white dots are usually clustered into a big white patch" ( Qi et al. 1986: 63, 1989: 119) or "there are orange and white dots spread on the body" ( Zhang et al. 2016: 207), which is exactly the character that K. albopunctatus sp. nov. has and K. ramosus does not. In consequence, we consider that K. ramosus previously documented from the Yellow Sea is a misidentification of K. albopunctatus sp. nov.

Kaloplocamus albopunctatus sp. nov. differs from K. acutus by the presence of the prostate and in not having bright, carmine-red ramifications and white dots on the entire dorsum. According to Baba (1989), K. acutus has two lateral teeth, while K. albopunctatus sp. nov. has three lateral teeth. Additionally, K. acutus has six velar appendages while K. albopunctatus sp. nov. has eight velar appendages on the head. Kaloplocamus peludo has an opaque white, irregularly shaped line and brown dots on the dorsum and bears two types of appendages. Conversely, K. albopunctatus sp. nov. does not have these morphological characters and the appendages are uniform rather than differentiated into two types. Finally, K. albopunctatus sp. nov. can be distinguished from K. maru by the vas deferens that is differentiated into a prostate and the absence of the white diamond-shaped spot on the dorsum. Another feature that distinguishes K. albopunctatus sp. nov. from K. maru is that K. maru has a long ribbon of teeth with 68 rows of teeth on it, which clearly differs from the ribbon of K. albopunctatus sp. nov. that only has 24 rows of teeth.

Figures

Figure 3. Holotype of Kaloplocamus albopunctatus sp. nov., living specimen, 22 mm in length A dorsal view B lateral view.

Figure 4. Paratype LSGB hb 266000 0305 of Kaloplocamus albopunctatus sp. nov. SEM photographs of the radula and jaws A complete radula B, C outer marginal teeth D inner lateral teeth E rachis F jaws. Scale bars: 500 μm (A); 200 μm (B); 100 μm (D); 20 μm (C, E); 100 μm (F).

Figure 5. Paratype LSGB hb 266000 0305 of Kaloplocamus albopunctatus sp. nov., diagram of the reproductive anatomy. Abbreviations: am - ampulla; bc - bursa copulatrix; f - female gland mass; p - prostate; s - receptaculum seminis; u - uterine duct; v - vagina; vd - vas deferens. Scale bar: 1000 μm.