taxonID	type	description	language	source
6E6E87DDFFC6FF8693F4B2B5FB66FE4D.taxon	description	Linnaeoxanthinae Števčić, 2005: 45.	en	Mendoza, Jose Christopher E., Clark, Paul F., Ng, Peter K. L. (2012): The identity of Pilumnoplax acanthomerus Rathbun, 1911 (Crustacea: Decapoda: Brachyura: Xanthidae), with new records from the central and western Pacific *. Zootaxa 3367 (1): 211-221, DOI: 10.11646/zootaxa.3367.1.20, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.3367.1.20
6E6E87DDFFC6FF8693F4B2B5FB66FE4D.taxon	diagnosis	Diagnosis. Carapace subhexagonal, wider than long; dorsal surface slightly convex, regions poorly indicated. Eyes relatively large. Supraorbital margin with distinct notch. Basal antennal article subrectangular, flagellum long. Posterior margin of epistome with median part straight. Male thoracic sternum wide; median line present only at level of sternites 7, 8. Chelipeds long, unequal; merus, carpus spinose; chelae flattened. Merus, carpus and propodus of ambulatory legs spinose on anterior margin; merus of P 2, P 3 with subdistal spine on posterior margin. G 1 relatively stout; G 2 about one-third length of G 1, terminal segment short. Male gonopore on coxa of P 5.	en	Mendoza, Jose Christopher E., Clark, Paul F., Ng, Peter K. L. (2012): The identity of Pilumnoplax acanthomerus Rathbun, 1911 (Crustacea: Decapoda: Brachyura: Xanthidae), with new records from the central and western Pacific *. Zootaxa 3367 (1): 211-221, DOI: 10.11646/zootaxa.3367.1.20, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.3367.1.20
6E6E87DDFFC6FF8693F4B2B5FB66FE4D.taxon	discussion	Remarks. See genus. Linnaeoxantho Štev č i ć, 2005	en	Mendoza, Jose Christopher E., Clark, Paul F., Ng, Peter K. L. (2012): The identity of Pilumnoplax acanthomerus Rathbun, 1911 (Crustacea: Decapoda: Brachyura: Xanthidae), with new records from the central and western Pacific *. Zootaxa 3367 (1): 211-221, DOI: 10.11646/zootaxa.3367.1.20, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.3367.1.20
6E6E87DDFFC6FF8693F4B2B5FB66FE4D.taxon	type_taxon	Type species. Pilumnoplax acanthomerus Rathbun, 1911, by monotypy; gender feminine.	en	Mendoza, Jose Christopher E., Clark, Paul F., Ng, Peter K. L. (2012): The identity of Pilumnoplax acanthomerus Rathbun, 1911 (Crustacea: Decapoda: Brachyura: Xanthidae), with new records from the central and western Pacific *. Zootaxa 3367 (1): 211-221, DOI: 10.11646/zootaxa.3367.1.20, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.3367.1.20
6E6E87DDFFC6FF8693F4B2B5FB66FE4D.taxon	diagnosis	Diagnosis. Carapace subhexagonal, wider than long; dorsal surface regularly finely granulate, slightly convex, regions poorly indicated. Front wide, bilobate, ventrally deflexed, with distinct row of granules posterior to frontal margin. Eyes relatively large, corneas well developed. Supraorbital margin with distinct notch. Basal antennal article subrectangular, flagellum long. Anterolateral margin much shorter than posterolateral margin; with 4 acute projecting teeth, including exorbital angle, fourth tooth small, spiniform. Buccal cavity widened anteriorly, not completely covered by third maxillipeds. Posterior margin of epistome with median part straight. Male thoracic sternum wide; median line present only at level of sternites 7, 8. Chelipeds long, unequal; merus, carpus spinose; chelae flattened; palm longer than fingers, fingers stout, grooved, with small tufts of setae; fixed finger with large tooth near tip, dactylus keeled on superior margin. Ambulatory legs moderately long, merus, carpus and propodus spinose on anterior margin; merus of P 2, P 3 with subdistal spine on posterior margin. G 1 relatively stout, distal half somewhat flattened, spinose, gently curved outward. G 2 about one third length of G 1, terminal segment short. Male gonopore on coxa of P 5, just anterior to coxo-sternal condyle.	en	Mendoza, Jose Christopher E., Clark, Paul F., Ng, Peter K. L. (2012): The identity of Pilumnoplax acanthomerus Rathbun, 1911 (Crustacea: Decapoda: Brachyura: Xanthidae), with new records from the central and western Pacific *. Zootaxa 3367 (1): 211-221, DOI: 10.11646/zootaxa.3367.1.20, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.3367.1.20
6E6E87DDFFC6FF8693F4B2B5FB66FE4D.taxon	discussion	Remarks. Rathbun (1911) originally assigned her species to Pilumnoplax (junior synonym of Eucrate), and by Serène (1968), with doubt, to Neopilumnoplax (Table 1). This species has been attributed to a number of families including Goneplacidae MacLeay, 1838, by Serène (1968), Euryplacidae, by Manning & Holthuis (1981) and Mathildellidae, by Karasawa & Kato (2003). But according to Guinot (1969), Ng & Manuel-Santos (2007) and Castro & Ng (2010), it does not belong to any of these families. Serène & Lohavanijaya (1973) also briefly mentioned that, due to its short G 2, the species does not belong to Goneplacidae-Carcinoplacidae. Goneplacids, euryplacids and mathildellids all have freely articulating abdominal somites 3 – 5 (Castro & Ng 2010: fig. 1; Ng & Manuel-Santos 2007: fig. 10 D – F) (vs. fused, Fig. 4 C). Furthermore, euryplacids have a G 1 tapering almost to a point (Castro & Ng 2010: figs. 11 E, 14) (vs. relatively stout and blunt, Fig. 4 F – H), and a long penis protected by a penial groove or tube (Castro & Ng 2010: figs. 16 E, 17 G) (vs. short, unprotected penis, Fig. 4 B). Mathildellids also have a slender, tapering G 1 (Ng & Manuel-Santos 2007: 45) (vs. stout, blunt G 1, Fig. 4 F – H), and a G 2 as long as the G 1 (Ng & Manuel-Santos 2007: 45) (vs. G 2 about half as long as G 1, Fig. 4 I). Despite the superficial carapace resemblance to some goneplacoids, Linnaeoxantho has more xanthoid characters, but its general morphology is so unusual that Števčić (2005) established Linnaeoxanthinae for it within Xanthidae. However, he did not provide any reason for this action other than a brief, generalized description. This present study suggests that Linnaeoxantho can be classified in the Xanthidae on account of the third to fifth somites of the male abdomen being immovably fused and the stout, curved G 1 which is twice as long as the G 2. Ng et al. (2008) did not follow the monotypic establishment of Linnaeoxanthinae as proposed by Števčić (2005) to accommodate Linnaeoxantho. Instead they retained this genus within the Xanthinae, prior to a re-examination of the types and an elucidation of the relationships within this apparently polyphyletic and artificial grouping. Recently, Lai et al. (2011) presented a molecular phylogeny of the Xanthidae, supported by morphological characters, the most comprehensive analysis on the family thus far. They showed that the subfamily Xanthinae is indeed polyphyletic, and suggested that more subfamily-level taxa should be recognised. Now that the type material has been found and more specimens have been examined, Linnaeoxantho is here considered most similar to the monotypic Melybia Stimpson, 1871, from the Caribbean (type species: Melybia thalamita Stimpson, 1871; see Stimpson, 1871: 144; A. Milne-Edwards, 1880: 275; Rathbun 1930: 562, pl. 230 figs. 1, 2; Williams 1984: 430, fig. 342) in the general shape of the carapace and pereiopods. In particular, both taxa have (1) a transversely subhexagonal carapace (Figs. 1, 2); (2) prominently quadridentate carapace anterolateral margins (Figs. 1, 2); (3) a relatively broad, bilobate and deflexed front (Figs. 2, 3 B); (4) a broad, oblique superior orbital margin, with large eyes and well-developed corneas (Fig. 2); (5) narrow mxp 3 which are widely separated from each other (Figs. 3 A, 3 B); (6) long, unequal chelipeds, with spinose meri and carpi, flattened chelae, with a double row of spiniform tubercles on the superior border of the palm, and fingers much shorter than the palm (Figs. 1, 2, 3 E, F); and (7) moderately long and slender ambulatory legs, with anteriorly spinose meri, with a differential occurrence of the subdistal spine on the posterior margin of the ambulatory meri, present only on P 2 and P 3 in Linnaeoxantho (Figs. 2, 4 D, E) (present in P 2 – P 4 in Melybia) (see also Melybia forceps A. Milne-Edwards, 1880: 274, pl. 49, figs. 1 – 1 e, a junior synonym of M. thalamita). A good series of specimens of M. thalamita were examined in the USNM for the present study and the resemblance between these two taxa is remarkable. Indeed, perhaps the only reason why this connection has not been made until now is due to the disparate distributions of these two taxa, and the relative rarity of L. acanthomerus. Interestingly, Števčić (2005: 88) was of the opinion that Melybia merited its own family, Melybiidae Števčić, 2005, but he inexplicably classified it in the Portunoidea Rafinesque, 1815. However, his treatment of Melybiidae and its characters was cursory and unhelpful for comparative purposes. He also does not explain why he placed Melybiidae in the Portunoidea and not within Linnaeoxanthinae. Melybiidae was first used in a letter by Števčić to Martin & Davis (2001: 112), but as the name was not acompanied by any diagnosis or description. Melybiidae Števčić in Martin & Davis, 2001, must be regarded as a nomen nudum, and the first valid use of the name was in Števčić (2005). This present study agrees with Ng et al. (2008) in assigning Melybia to the Xanthidae, prior to a systematic revision of this group. However, both Linnaeoxantho and Melybia are here considered related, and fall within or are allied to what is now understood as the Xanthidae (viz. Lai et al. 2011). Linnaeoxantho and Melybia share a suite of diagnostic characters (see diagnoses for subfamily and genus) that distinguish them from the Xanthinae s. str. (viz. Lai et al., 2011) and suggest that they can be placed in their own subfamily, for which the names Linnaeoxanthinae Števčić, 2005, and Melybiinae Števčić, 2005, are available. However, as the names appeared in the same paper (Števčić 2005), the Code regards both as simultaneously published and neither has priority. In such a case, the First Reviser principle comes into effect. Therefore, Linnaeoxanthinae Števčić, 2005, is chosen here as having priority over Melybiinae Števčić, 2005, whenever these two taxa are regarded as synonyms.	en	Mendoza, Jose Christopher E., Clark, Paul F., Ng, Peter K. L. (2012): The identity of Pilumnoplax acanthomerus Rathbun, 1911 (Crustacea: Decapoda: Brachyura: Xanthidae), with new records from the central and western Pacific *. Zootaxa 3367 (1): 211-221, DOI: 10.11646/zootaxa.3367.1.20, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.3367.1.20
6E6E87DDFFC0FF8A93F4B363FE9EFD51.taxon	description	(Figs. 1 – 4)	en	Mendoza, Jose Christopher E., Clark, Paul F., Ng, Peter K. L. (2012): The identity of Pilumnoplax acanthomerus Rathbun, 1911 (Crustacea: Decapoda: Brachyura: Xanthidae), with new records from the central and western Pacific *. Zootaxa 3367 (1): 211-221, DOI: 10.11646/zootaxa.3367.1.20, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.3367.1.20
6E6E87DDFFC0FF8A93F4B363FE9EFD51.taxon	materials_examined	Material examined. Types: holotype ♂, 12.9 × 8.5 mm, paratype 1 ♀ ovig., 15.0 × 10.1 mm (USNM 41353), stn E 21, 54 m (30 fms), Amirante Islands, coll. J. Stanley Gardiner, H. M. S. Sealark, 17 Oct. 1905. Additional material: 1 ♂, 7.1 × 5.5 mm (ZRC 2012.0160), “ Dive Ola ”, scuba, 24 m, Kumejima Is., Ryukyu Islands, Japan, coll. P. F. Clark et al., 9 Nov. 2009; 1 ♀, 11.0 × 7.5 mm (UF 10556), outer reef slope, from dead Pocillopora head, 10 – 15 m, Tabuaeran Atoll, Kiribati, Line Islands, coll. G. Paulay & N. Knowlton, 12 Aug. 2005.	en	Mendoza, Jose Christopher E., Clark, Paul F., Ng, Peter K. L. (2012): The identity of Pilumnoplax acanthomerus Rathbun, 1911 (Crustacea: Decapoda: Brachyura: Xanthidae), with new records from the central and western Pacific *. Zootaxa 3367 (1): 211-221, DOI: 10.11646/zootaxa.3367.1.20, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.3367.1.20
6E6E87DDFFC0FF8A93F4B363FE9EFD51.taxon	description	Description of holotype. Carapace (Fig. 2 A) subhexagonal, width about 1.5 × length; dorsally slightly convex, dorsal surface covered with several, discrete, round granules, larger on anterior third; regions mostly not well defined, anterior part of 2 M, 3 M well delineated by narrow, shallow grooves, 2 M undivided. Front relatively wide, about 0.4 × maximum carapace width; slightly deflexed ventrally; separated from orbits by deep notch; separated into 2 lobes by shallow median notch; anterior margin sinuous, lateral lobes moderately prominent, with distinct, neat row of granules immediately posterior. Anterolateral margin about half length of posterolateral margin; armed with 4 acute, projecting teeth, including exorbital tooth; first (exorbital) tooth broadest at base, fourth smallest, spiniform; carapace widest at level of third tooth; posterolateral margin straight; central portion of posterior margin slightly concave. Suborbital, subhepatic, pterygostomian regions granulate. Orbits (Fig. 2 A) large, margins finely granulate, subcristate; superior, inferior orbital margins each with distinct notch, continuing posteriorly as short fissure; eyes large, ocular peduncles short, stout, corneas well developed. Antennular fossae (Fig. 3 B) large, antennules folding transversely. Basal article of antennae (Fig. 3 B) subrectangular, with small distolateral extension entering orbital hiatus; antennal flagellum long, exceeding exorbital angle by one-third of its length. Epistome (Fig. 3 B) broad; central region of posterior margin nearly straight, lateral regions of posterior border convex. Endostome without oblique ridges. Mxp 3 (Fig. 3 A, B) smooth, slender, not completely closing buccal cavity; merus subquadrate, median length about 0.4 × median length of ischium; ischium subrectangular, with shallow submedian sulcus; exopod long, subrectangular, with prominent mesial projection subdistally. Thoracic sternum (Figs. 3 A, 4 B) broad, finely granulate; sternites 1, 2 fused, large, separated from sternite 3 by distinct suture 2 / 3; sternites 3, 4 almost completely fused except at lateral edges; sternite 4 broad, without visible median line; sternites 5, 6 similar in shape, sternite 7 with anterior portion much larger than episternite, sternite 8 completely covered by abdominal somite 3; sternal press-button on posterior half of sternite 5, closer to suture 5 / 6; sutures 4 / 5, 5 / 6 interrupted medially, sutures 6 / 7, 7 / 8 complete; median, membranous, uncalcified region at level of suture 6 / 7; median line only visible at level of sternites 7, 8. Chelipeds (P 1) (Fig. 1, 2, 3 E, F) unequal. Meri finely granulate, long, distal portions well exceeding margins of carapace; anterior margin armed with four conspicuous spines distributed along entire length. Carpus coarsely granulate on external surface; with 2 prominent spines on inner angle, 1 on top of the other; large conical granules interspersed on dorso-distal and dorso-internal margins. Major chela broad, flattened; superior margin of palm with double row of conical granules; internal and external surfaces of palm finely granulate; fingers about half length of palm, tips strongly recurved, with discrete, small tufts of stiff setae; pigment localized throughout length of fingers, except tips, also on distal fourth of palm; dactylus with dorsal keel and longitudinal groove on both external and internal surfaces; cutting margin of dactylus with several low teeth, cutting margin of fixed finger with one broad, molariform tooth, set apart from distal tip by deep notch. Minor chela nearly identical in form but smaller. Ambulatory legs (P 2 – P 5) (Figs. 1, 2, 4 D, E) relatively long, with long setae; P 2, P 5 shortest, P 3, P 4 longest; total length of P 4 about 1.5 × maximum carapace width. Meri flattened, length about 2.7 × width; anterior margin armed with several spines throughout entire length; posterior margin with strong spine subdistally on P 2, P 3, absent in P 4, P 5. Carpi, propodi similarly spinose on anterior margins. Dactyli straight, ending in chitinous claw. Short, stiff spiniform setae on posterior margins of propodi and on anterior and posterior margins of dactyli. Abdomen (Fig. 3 A, 4 C) short, tip of telson reaching just posterior to level of coxo-sternal condyles of P 1 coxae. Abdominal somites 1, 2 (ab 1, 2) trapezoidal, width 6.0 – 8.0 times length; somites 3 – 5 (ab 3 – 5) fused, lateral margins greatly concave, vestiges of sutures visible externally as small lateral notches; posterolateral regions of ab 3 with cupuliform depression, locking with episternite 7 in closed abdomen; somite 6 (ab 6) subrectangular, width about 1.8 times length, lateral margins slightly concave. Telson subtriangular, tip rounded, lateral margins slightly convex; subequal in length to ab 6. G 1 (Figs. 4 F – H) short, stout, curved; distal tip reaching just beyond level of sternal suture 5 / 6, into small, shallow, transverse depression; distal half covered with conical granules, short spiniform setae towards distal tip; distal tip bilobate, without long, plumose subterminal setae. G 2 (Fig. 4 I) nearly straight; slightly more than onethird length of G 1; terminal process about 0.3 times total length. Penis relatively short (Fig. 4 B) emerging from large gonopore, located just anterior to coxo-sternal condyle of P 5. Female morphology. Similar in most respects to male (see Figs. 2 B, C, 3 B), except for sexual characters; abdomen broader, all somites and telson freely articulated; vulvae (Fig. 3 D) moderate in size, oval, positioned on thoracic sternite 6, mid-way between sutures 5 / 6, 6 / 7, membrane nearly completely covering gonopores. Chelipeds, in particular meri, relatively shorter than in the male; dark pigmentation limited to fingers of chela. Coloration (Fig. 1). Carapace reddish-brown, symmetrically specked with yellow on anterior regions and anterolateral margins. Cornea of eyes also reddish-brown. Chelipeds same color as carapace, meri banded alternately with reddish-brown and dirty white; fingers dark brown except, at tips which are white, dark brown pigment extending onto palm in males. Ambulatory meri banded reddish-brown and dirty white, with dirty white bands at joints of carpi, propodi and dactyli. Long, stiff setae on ambulatory legs yellow. See also a colour photo of an uncollected specimen from Indonesia (Humann & DeLoach 2010: 185).	en	Mendoza, Jose Christopher E., Clark, Paul F., Ng, Peter K. L. (2012): The identity of Pilumnoplax acanthomerus Rathbun, 1911 (Crustacea: Decapoda: Brachyura: Xanthidae), with new records from the central and western Pacific *. Zootaxa 3367 (1): 211-221, DOI: 10.11646/zootaxa.3367.1.20, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.3367.1.20
6E6E87DDFFC0FF8A93F4B363FE9EFD51.taxon	discussion	Remarks. The occurrence of Linnaeoxantho acanthomerus in the Ryukyu and Line Islands (Figs. 1, 2 C, D), including one photographic record from Indonesia (no specimens collected; Humann & DeLoach, 2010), significantly widens the range of this species. The type specimens were dredged from a depth of about 54 m, but the new material reveals that this species also occurs at shallower depths (depth range: 10 – 54 m). From the notes of the collectors of the new material it is also apparent that this species can be found amongst living or dead corals on reef slopes.	en	Mendoza, Jose Christopher E., Clark, Paul F., Ng, Peter K. L. (2012): The identity of Pilumnoplax acanthomerus Rathbun, 1911 (Crustacea: Decapoda: Brachyura: Xanthidae), with new records from the central and western Pacific *. Zootaxa 3367 (1): 211-221, DOI: 10.11646/zootaxa.3367.1.20, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.3367.1.20
