Gaillardiellus magiruber, Ziming & Wei & Zhongli, 2025

Ziming, Yuan, Wei, Jiang & Zhongli, Sha, 2025, A new species of Gaillardiellus Guinot, 1976 (Crustacea, Brachyura, Xanthidae) from the coral reefs of the South China Sea, ZooKeys 1234, pp. 1-17 : 1-17

publication ID	https://doi.org/10.3897/zookeys.1234.144026
publication LSID	lsid:zoobank.org:pub:E5C71E6F-577A-45F8-8B44-7D2DBEE09299
DOI	https://doi.org/10.5281/zenodo.15185125
persistent identifier	https://treatment.plazi.org/id/578CCEE8-4572-5897-B4A4-2FE8550FC5F9
treatment provided by	ZooKeys by Pensoft
scientific name	Gaillardiellus magiruber
status	sp. nov.

Treatment

Gaillardiellus magiruber sp. nov.

Figs 1 View Figure 1 , 2 View Figure 2 , 3 View Figure 3 , 4 View Figure 4 , 5 View Figure 5 , Suppl. material 1

Material examined.

Holotype: China • ♂, 5.9 × 4.4 mm; Xisha Islands, Tree Island ; depth 58 m; 2 Jul. 1977; Dong Dong leg.; MBM 288133 View Materials . Paratypes: China • 1 ♀, 9.8 × 7.1 mm; Nansha Islands, Mischief reef ; 9°54'N, 115°34'E; depth 1 m; 11 May 2022; Yuan Ziming, Sun Yuli, Ma Shaobo leg.; MBM 288134 View Materials GoogleMaps • 1 ♀, 9.5 × 6.4 mm; Nansha Islands, Banyue Reef ; 29 Sep. 1994; MBM 164284 View Materials • 1 ♀, 5.7 × 4.2 mm; Xisha Islands, Qilianyu Islands ; 16°58'N, 112°16'E; depth 10 m; 19 May 2022; Yuan Ziming, Sun Yuli, Ma Shaobo leg.; MBM 288135 View Materials GoogleMaps • 1 juvenile ♂, 4.5 × 3.5 mm; Xisha Islands, North Reef ; depth 30 m; 1 Sep. 2024; Dong Dong leg.; MBM 288136 View Materials • 1 juvenile ♂, 4.2 × 3.3 mm; Xisha Islands, Huaguang Reef ; depth 31 m; 26 Aug. 2024; Dong Dong leg.; MBM 288137 View Materials • 1 juvenile ♀, 4.5 × 3.4 mm; Xisha Islands, Yagong Island ; depth 33 m; 19 Aug. 2024; Dong Dong leg.; MBM 288138 View Materials • 1 juvenile ♀, 4.1 × 3.0 mm; Xisha Islands, Yagong Island ; depth 31 m; 20 Aug. 2024; Dong Dong leg.; MBM 288139 View Materials .

Comparative material.

Gaillardiellus rueppellii ( Krauss, 1843) (Figs 6 A, B View Figure 6 , 7 View Figure 7 ) China • 1 ♂; Xisha Islands , Money Island; 17 Mar. 1977; IOZ 31604-01 - 4 • 1 ♂; Hainan, Dachan Island ; 25 Mar. 2018; MBM 288140 View Materials • 1 ♂; Hainan, Lingao Bay ; depth 15–30 m; 20 Aug. 2018; Pan Yunhao leg.; MBM 288141 View Materials • 1 ♂; Guangxi, Weizhou Island ; 19 Nov. 2018; MBM 283642 View Materials . CW 25.3–45.6 mm, CL 19.4–34.4 mm. Gaillardiellus orientalis (Odhner, 1925) (Fig. 6 C, D View Figure 6 ) China • 1 ♂, 34.9 × 25.8 mm; Shandong, Qingdao ; 22 Jul. 2015; Yang Bin leg.; MBM 288142 View Materials . Gaillardiellus superciliaris (Odhner, 1925) (Fig. 6 E, F View Figure 6 ) China • 1 ♂, 11.6 × 7.9 mm; Zhongsha Islands GoogleMaps , Zhongbei Shoal; 16°5'N, 114°25'E; 6 May 2024; Yuan Ziming leg.; MBM 288143 View Materials .

Diagnosis.

Carapace (Figs 1 A, B View Figure 1 , 2 A View Figure 2 , 3 A, B View Figure 3 , 4 A, B View Figure 4 ) transversely oval, regions clearly defined, short setae present within grooves and between granules, long setae scattered between granules; front not protruding, slightly curved downwards, divided into 2 lobes by broad V-shaped notch; anterolateral margin divided into 4 granular lobes, first lobe small, slightly larger than outer orbital angle, adjacent to latter; posterolateral margin shorter than anterolateral margin, distinctly concave. Thoracic sternum (Figs 1 D View Figure 1 , 3 D View Figure 3 ) with low granules, sternites 1 to 4 covered with soft setae. Male pleonite 6 (Figs 1 D View Figure 1 , 2 B View Figure 2 ) with expanded lateral distal angles, wider than long; telson wider than long, terminal end blunt. G 1 (Fig. 2 F, G, J, K View Figure 2 ) curved outwards, distal third with small spines, long setae near distal end, terminal lobe slender. Orange-red to vibrant bright red in life (Fig. 5 View Figure 5 ).

Description of male holotype.

Carapace (Figs 1 A, B View Figure 1 , 2 A View Figure 2 ) transversely oval, CW about 1.3 times CL, dorsal surface slightly elevated, regions clearly defined, covered with granules, grooves wide and deep; short setae present within grooves and between granules, long setae scattered between granules; regions 1–3 M distinct, 2 M completely divided into 2 lobes, 3 M intact, 4 M indistinct; regions 2–6 L distinct, 1 P distinct, 2 P indistinct; front about 0.3 times CW, not protruding, slightly curved downwards, divided into 2 lobes by broad V-shaped notch, inner lobes rounded and more prominent, outer lobes smaller and flatter, separated from inner orbital angle by notch; dorsal orbital margin with 2 sutures; eyestalks with setae and granules near cornea. Outer orbital angle not fused with anterolateral margin; anterolateral margin divided into 4 granular lobes, first lobe small, slightly larger than outer orbital angle, adjacent to latter, second and third lobes broader, fourth lobe smaller than third; posterolateral margin shorter than anterolateral margin, distinctly concave; subhepatic region with granules and short setae; pterygostomial region smooth with soft setae.

Antennule (Fig. 1 C View Figure 1 ) folding transversely, antennular fossa subrectangular; basal segment of antenna subrectangular, filling orbital hiatus, antennal flagellum fitting into orbital hiatus. Epistome (Fig. 1 C View Figure 1 ) central region with a strong median projection on posterior margin. Third maxilliped merus subquadrate, with low granules, anterior margin slightly indented, outer distal angle slightly expanded; ischium subrectangular, with submedian groove.

Chelipeds (Figs 1 E View Figure 1 , 2 C View Figure 2 ) symmetrical, merus margins with low granules and soft setae; carpus robust, densely covered with granules and long setae, dorsolateral surface with grooves; palm densely covered with granules and setae on dorsal and lateral surfaces, ventral and medial surfaces smoother with low granules, dorsal surface with 2 granular tubercles; gap present when fingers closed; basal part of movable finger with granules, dorsal surface with 2 grooves, 3–5 rounded teeth between fingers, tips slightly concave.

Ambulatory legs (Figs 1 A View Figure 1 , 2 D View Figure 2 ) densely covered with setae and granules; merus concave near terminal end of dorsal margin; carpus with groove near anterior margin, slightly swollen near terminal end; propodus nearly rhomboid; dactylus almost as long as propodus, terminal end chitinous, long, and sharp, with underdeveloped dactylo-propodal lock.

Thoracic sternum (Fig. 1 D View Figure 1 ) with low granules, sternites 1 to 4 covered with soft setae; sternites 1 and 2 fused, suture between sternites 2 and 3 straight, suture between sternites 3 and 4 visible at margins, extending as shallow groove towards center, slightly curving backwards, with sternite 4 partially covered by telson, central groove beneath telson; tubercle of sterno-pleonal lock (press-button mechanism) located on anterior margin of sternite 5.

Pleon (Figs 1 D View Figure 1 , 2 B View Figure 2 ) relatively short, pleonites 3 to 5 fused, fusion lines visible, margins concave and sinuous, fitting closely to corresponding part of thoracic sternum; pleonite 6 with expanded lateral distal angles, wider than long; telson (Figs 1 D View Figure 1 , 2 B View Figure 2 ) wider than long, terminal end blunt, with long soft setae.

G 1 (Fig. 2 F, G, J, K View Figure 2 ) curved outward, distal third with small spines, long setae near distal end, terminal lobe slender. G 2 (Fig. 2 H, I View Figure 2 ) about one-third length of G 1, curved outwards, terminal lobe longer and curved upwards.

Note on paratypes.

In the current paratypes, an adult female exhibits the largest body size (9.8 × 7.1 mm; MBM 288134, Figs 3 View Figure 3 , 4 View Figure 4 , 5 A, B View Figure 5 ). Compared to the male holotype, the female paratype possesses a broader and more expanded carapace and a more concave posterior margin (Figs 3 A, B View Figure 3 , 4 A View Figure 4 ), which may reflect a higher level of maturity in this species. In smaller individuals and juveniles, the carapace is narrower.

The overall morphology of the female is similar to that of the male, with the following sexual dimorphic characteristics: female pleon broad, oval-shaped (Fig. 4 F View Figure 4 ); telson terminal end blunt (Fig. 4 F View Figure 4 ); and vulva located at the anterior margin of the sternite 6, with an oval-shaped cover (Figs 3 D View Figure 3 , 4 G View Figure 4 ).

Colour in life.

In the current specimens, as body size increases, the coloration changes from a lighter orange-red with bright red spots (Fig. 5 C View Figure 5 ) to a totally vibrant bright red (Fig. 5 A View Figure 5 ). The cheliped fingers change from having a white distal half and a brown base (Fig. 5 C View Figure 5 ) to being entirely white along their length (Fig. 5 A View Figure 5 ).

Etymology.

The new species is named after the fiery Stand “ Magician’s Red ” from the manga “ JoJo’s Bizarre Adventure ”, wielded by the character Muhammad Avdol. This name alludes to the species’ changing flame-like red coloration.

Remarks.

Gaillardiellus magiruber sp. nov. should be placed within Gaillardiellus based on the well-defined regions on the dorsal carapace, the morphology of the granules and setae, the presence of four granular rounded lobes on the anterolateral margin (Figs 1 B View Figure 1 , 2 A View Figure 2 ), the absence of nodules on the ambulatory legs (Figs 1 A View Figure 1 , 2 D View Figure 2 ), and the sinuous margins of male pleonites 3–5, along with the overall morphology of the thoracic sternum (Fig. 2 B View Figure 2 ). The anterolateral margin of G. magiruber sp. nov. is completely separated from the outer orbital angle (Figs 1 A View Figure 1 , 2 A View Figure 2 , 3 B View Figure 3 , 4 A View Figure 4 ), which distinguishes it clearly from G. superciliaris and G. alphonsi as their outer orbital angle is fused with the first anterolateral lobe (cf. Guinot 1976: pl. 16 figs 4, 5). Additionally, the well-developed long setae on the dorsal surface of the carapace and the evenly rounded teeth on the immovable finger of the cheliped further differentiate this new species from G. holthuisi and G. bathus . In contrast, G. holthuisi and G. bathus have only sparse long setae, and they also differ in the placement of a strong tooth: in G. holthuisi , it is near the tip of the immovable finger, while in G. bathus , it is in the middle part of the immovable finger (cf. Davie 1997: figs 1 b, 15 c; Takeda and Komatsu 2010: figs 1, 2 B).

Gaillardiellus magiruber sp. nov. is most similar to two closely related congeners, i. e., G. rueppellii and G. orientalis . Considering the scattered distribution of setae on the dorsal surface of the carapace, rather than the distinct tufted clusters in G. orientalis (cf. Guinot 1976: pl. 16, fig. 2), G. magiruber sp. nov. is especially similar to G. rueppellii and could be confused with it. Gaillardiellus rueppellii was first reported from Natal, South Africa and is widely known in the Indo-West Pacific region ( Krauss 1843; Guinot 1976; Serène 1984). Guinot (1976) provided a detailed redescription of the type specimen, accompanied by refined photographs and illustrations (cf. Guinot 1976: figs 42 A, 43 A, 43 a, 44 B, pl. 16, fig. 1, 1 a), enhancing the understanding of G. rueppellii . Gaillardiellus magiruber sp. nov. can be distinguished from G. rueppellii by the following characteristics: the front being broader and non-protruding, about 0.3 times CW (Figs 1 B View Figure 1 , 2 A View Figure 2 ) (vs. front narrower and protruding, about 0.2 times CW in G. rueppellii ; Fig. 6 A View Figure 6 ; cf. Guinot 1976: pl. 16, fig. 1); the first anterolateral lobe is almost adjacent to the outer orbital angle, with no additional lobe underneath (Figs 1 B, C View Figure 1 , 2 A View Figure 2 ) (vs. a wider gap between the first anterolateral lobe and outer orbital angle, with an accessory lobe underneath in G. rueppellii ; Fig. 6 B View Figure 6 ; cf. Guinot 1976: pl. 16, fig. 1); the male and female thoracic sternum with long soft setae on sternites 1–4 (Figs 1 D View Figure 1 , 3 D View Figure 3 ) (vs. only sparse short setae in G. rueppellii ; Fig. 6 B View Figure 6 ); the male pleon is shorter, the pleonite 6 and telson being broader than long, and the telson with long soft setae on tip (Figs 1 D View Figure 1 , 2 B View Figure 2 ) (vs. male pleon is longer, the pleonite 6 and telson are nearly equal in length and width, and the telson without long soft setae in G. rueppellii ; cf. Guinot 1976: fig. 62 A); the G 1 is shorter and stouter (Fig. 2 J, K View Figure 2 ) (vs. G 1 slender in G. rueppellii ; cf. Guinot 1976: fig. 63 A). Additionally, G. magiruber sp. nov. has a more vibrant bright red live coloration (Fig. 5 View Figure 5 ) (vs. duller coloration, appearing brownish in G. rueppellii ; Fig. 7 View Figure 7 ).

Furthermore, although the present specimens of G. magiruber sp. nov. include some juvenile individuals, considering the body size of the two female specimens displaying distinct maturity traits, such as the well-developed pleon and vulva, the new species is relatively smaller in size (CW less than 10 mm) compared to most congeners.

It is worth noting that G. rueppellii has two early synonyms: Actaea pilosa Stimpson, 1858 , from Hong Kong, and Aegle rugata Adams & White, 1849 (not H. Milne Edwards, 1834), from the Philippine Islands. Unfortunately, the type specimen of Aegle rugata is no longer traceable (Dr Paul Clark, Natural History Museum, personal communication), and the type specimen of Actaea pilosa was likely lost in the infamous fire. The identities of these two specimens remain uncertain. However, based on the limited available illustrations ( Stimpson 1907: pl. 5 fig. 6; Adams and White 1849: pl. 8, fig. 5), both species exhibit a prominently lobed frontal margin, suggesting closer affinity to G. rueppellii rather than G. magiruber sp. nov. Due to the similarities between the two species, G. magiruber sp. nov. may be mistakenly identified as a juvenile of G. rueppellii . Further extensive examination will help clarify the distribution ranges of both species.

In the COI - based molecular analysis, the BI (Fig. 8 View Figure 8 ) and ML (Suppl. material 2) trees exhibited similar topologies. Gaillardiellus magiruber sp. nov. is most closely related to G. orientalis , followed by clustering with G. rueppellii . Species delimitation based on ABGD and bPTP further supports the validity of the new species.

In addition, Paractaea Guinot, 1969 , is not monophyletic in the current study, with P. tumulosa (Odhner, 1925) and P. cf. excentrica (Guinot, 1969) forming a single clade. Serène (1984) previously suggested transferring P. tumulosa to Paractaeopsis Serène, 1984 (see Takeda and Komatsu 2018). Further research is needed to clarify the phylogenetic relationships among species within Paractaea .

Geographic distribution.

Xisha and Nansha Islands, South China Sea.