Tuerkayana Guinot & Ng & Rodríguez Moreno 2018, n. gen.
Creators: name: Guinot, Danièle
name: Ng, Ngan Kee
name: Rodríguez Moreno, Paula A.
Publisher: name: Zenodo
Year: 2018
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Decapoda
Gecarcinidae
Tuerkayana

description: Genus Tuerkayana n. gen.
urn:lsid:zoobank.org:act: 7C204D39-B983-415C-A855-8F89B59F1322
TYPE SPECIES BY PRESENT DESIGNATION. — Thelphusa rotunda
Quoy & Gaimard, 1824. The type material is preserved in the MNHN, and a lectotype will be selected by N. K. Ng et al. (in press: fig. 3B). Gender neuter.
OTHER SPECIES. — Tuerkayana celeste (Ng & Davie, 2012) n. comb.; T. magnum (Ng & Shih, 2014) n. comb.; T. hirtipes (Dana, 1851) n. comb. Seen as the type of Cardisoma hirtipes Dana, 1851 recently found in the USNM that was designated as lectotype by Ng (2017: figs 1-3) it matches well with the figures of Dana (1855: pl. 24, fig. 4). In order to avoid confusion regarding the identity and the morphology of the species, we will base our comparisons on the illustrations of these two authors. The complicated question about the identity of C. hirtipes is developed in the Appendix.
ETYMOLOGY. — Named in honour of our colleague and friend Michael Türkay, who died too soon in 2015, for his outstanding contribution to carcinology. He is the acknowledged specialist of land crab systematics, author of important papers in the 1970s devoted to the study of these crabs.
DIAGNOSIS
Carapace moderately inflated, convex tranversely and longitudinally; dorsal surface with poorly or well demarcated regions, smooth or granulated along anterolateral borders (Fig. 4 F-I, T. aff. hirtipes n. comb., T. rotundum n. comb., T. celeste n. comb., T. magnum n. comb., respectively); weak but distinct posterolateral striae, may disappear in largest adults (Fig. 4F, T. aff. hirtipes n. comb.) (Ng 2017: fig. 2A, lectotype of Cardisoma hirtipes); anterolateral margin delimited by a row of fine granules (Fig. 4H, I, T. celeste n. comb., T. magnum n. comb., respectively) or by a continuous, long row of distinct granules (Fig. 4G, T. rotundum n. comb.) or anterolateral margin strongly convex, rounded (Fig. 4F, T.aff. hirtipes n. comb.); just behind the exorbital angle, a small notch or an indentation with small tooth (Fig. 4 G-I, T. rotundum n. comb., T. celeste n. comb., T. magnum n. comb., respectively) (Ng 2017: fig. 2A, B, lectotype of Cardisoma hirtipes). Proepistome dome-shaped, wide but rather low (Fig. 6 C-E) (Ng 2017: fig. 2B, lectotype of Cardisoma hirtipes); orbit with lateral gap closed by obliquous margin; no suborbital crest (Fig. 6 C-E). Subhepatic and subbranchial areas not striated (Ng & Shih 2014: figs 9A-D, Discoplax hirtipes, D. celeste, D. magna, respectively). Setose pterygostomial area broad.Male chelipeds without maked heterochely: major chela moderately developed but becoming very stout in large adult males, fingers elongated (Ng & Shih 2014: fig. 6A-C, Discoplax celeste; Ng 2017: fig. 3A, B, lectotype of C. hirtipes) or swollen and with relatively short fingers (T. rotundum n. comb.); chela of large adult males of T. magnum n. comb. not especially enlarged in proportion to long fingers; fingers elongated, partially flattened laterally, sometimes appearing almost blade-like. Pereiopods variously shaped: short, relatively slender, especially merus and propodus (Ng 2017: fig. 3C-H, lectotype of Cardisoma hirtipes) or relatively stout, short, especially merus and propodus (T. celeste n. comb.), or relatively stout, short to slender (T. magnum n. comb.). Thoracic sternum (Fig. 5 G-O) tilted posteriorly, proportionally wide, especially at level of sternite 4 that is not much restricted between the P1; sternite 1 small, triangular; sternite 2 broad, dome-shaped; suture 1/2 as a more or less arcuate, granulated thick ridge; suture 2/3 complete, straight; granulated thick ridge; suture 2/3 complete, straight; no suture 3/4, without lateral trace; sternite 4 proportionally wide and short; on sternite 4 a ridge forming the rim of sternopleonal cavity at level of telson; thick, wide bridge at level of suture 6/7; sternite 8 large, developed medially; no visible portion when pleon is folded; suture 7/8 rather short. Median line present on sternite 8 and extending on sternite 7 below median bridge (Fig. 5H, I, T. aff. hirtipes n. comb.; Fig. 5K, L, T. celeste n. comb.; Fig. 5N, O, T. magnum n. comb.) (Ng 2017: fig. 2D, E, lectotype of Cardisoma hirtipes); correspondingly, median septum lacking in dissected T. aff. hirtipes. Pleon (Fig. 5G, J, M) (Ng 2017: fig. 2E, F, lectotype of Cardisoma hirtipes) elongated, reaching sternite 3; somite 6 broad and short; telson short, bluntly tipped. G1: see Ng & Shih 2014: fig. 13A-E, F-J, K-O, as Discoplax hirtipes, celeste, magnum, respectively. Male gonopore close to P5 coxo-sternal condyle. Penis (Fig. 5I, L, O) with narrow proximal portion passing between sternite 7 and sternite 8, continuing by calcified cylindrical tube and then developing into large papilla (sometimes not exposed due to a short fusion of sternite 7 and sternite 8); sternite 8 usually exposed when pleon is folded.
REMARKS
The features related to carapace and chelae considerably vary depending on the size, so the use to other more constant traits is required.
Tuerkayana n. gen. differs from Discoplax chiefly by: the body shape, more inflated; anterolateral margins slightly, hardly or not demarcated; posterolateral striae on carapace weaker and faint or lost at largest size (Fig. 4F, T. aff. hirtipes) (Ng 2017: fig. 2A, lectotype of Cardisoma hirtipes) (present in Discoplax even at large size, see Ng & Shih 2015: fig. 3); proepistome wide and dome-shaped (Fig. 6 C-E) instead of narrow, subquadrate projection in Discoplax (Fig. 6A) (Ng & Shih 2015: fig. 7); orbit laterally closed, without stridulating suborbital crest (Fig. 6 C-E) (Ng 2017: fig. 2B, C, lectotype of Cardisoma hirtipes); absence of smooth ridge (plectrum) on cheliped merus, thus no stridulatory apparatus; thoracic sternum proportionally longer and narrow, with posterior sternites steeply sloping; sternite 4 longer, narrower, much restricted between the P1, with concave lateral margins (Fig. 5G, H, J, K, M, N) (Ng 2017: fig. 2E, lectotype of Cardisoma hirtipes); sternite 2 rather broad, rectangular; thick pleonal rim on sternite 4; episternites 4-6 wide, horizontally directed; median line on sternite 7, not extending on sternite 6 (Fig. 5I, L, O); a moderate bridge at level of suture 6/7; long pleon, with elongate pleonal somite 6 (Fig. 5G, J, M) and long telson; absence of sternal press-button (Köhnk et al. 2017: 2111 as Discoplax; see also Guinot & Bouchard 1998).
Tuerkayana n. gen. differs from Cardisoma sensu stricto by: carapace moderately inflated, convex tranversely and longitudinally (Fig. 4 F-I) (vs inflated and thick in Cardisoma, Fig. 4 A-C); dorsal surface with poorly or well demarcated regions (vs regions weakly or hardly demarcated, smooth in Cardisoma); posterolateral striae weak but distinct (Fig. G-I), may disappear in largest adults (Fig. 4F) (without posterolateral striae in Cardisoma, Fig. 4 A-C); proepistome dome-shaped but rather low (vs prominently dome-shaped in Cardisoma); male chelipeds without marked heterochely: major chela moderately developed but becoming very stout in large adult males (vs with strong heterochely and heterodonty: major chela very stout, minor chela narrow, long); sternite 4 wide and short (vs narrow and long); median line present only on sternites 8 and 7 below transverse bridge (vs on sternites 8, 7 and extending on the whole sternite 6, in front of transverse bridge); pleonal somite 6 (Fig. 5G, J, M) broad and short; telson short, bluntly tipped (vs pleonal somite 6 narrow and conspicuously elongated; telson elongated).
Tuerkayana rotundum n. comb., a species largely distributed in the Indo-West Pacific, living in the supralittoral or inland habitats and only occasionally found in caves (Türkay 1974a, as Cardisoma; Ng & Guinot 2001, as Discoplax; Innocenti & Vannini 2007, as Discoplax), only superficially looks like a Discoplax by the flattened carapace, with well delimited anterolateral margins (Fig. 4G) (Ng & Guinot 2001: figs 2B, 4B) and the dorsal surface granulose on lateroanterior regions and striated on lateroposterior regions (thus its name of “rugose land crab”). In contrast, T. rotundum n. comb. can be easily distinguished from Discoplax by numerous characters, in particular by: orbit laterally closed and lacking suborbital crest; wide, dome-shaped proepistome; and sternal and pleonal features; P2, P3 elongated but not so distinctly, only 2-3 times carapace length (in D. longipes and D. gracilipes far more elongated, at least 4-5 times carapace length); sternal button lacking and no clear socket, see Köhnk et al. (2017: fig. 20c-d, as Discoplax); also Guinot & Bouchard (1998) (in D. longipes [Fig. 5B] and D. gracilipes, button close to suture 4/5 and surrounded by dense setae that obscure it, so probably not an efficient locking mechanism, see Köhnk et al. 2017: fig. 19a).
CHARACTERS SHARED BY LEPTOGRAPSODES, DISCOPLAX, CARDISOMA AND TUERKAYANA N. GEN.
1) The orbit with a large lateral gap closed by an obliquous margin and long, finely ornamented suborbital ridge, extending laterally below and beyond orbit, are characters shared by Leptograpsodes (Figs 1G; 2C; 3D) and Discoplax (Fig. 6A), but absent in Cardisoma (Fig. 6B)and Tuerkayana n. gen. (Fig. 6 C-E).
Cardisoma Latreille, in Latreille, Le Peletier, Serville & Guérin, 1828 Cardisoma guanhumi Cardisoma guanhumi Latreille, in Latreille,
Le Peletier, Serville & Guérin, 1828
(type species) Cardisoma armatum Cardisoma armatum Herklots, 1861 Cardisoma carnifex Cardisoma carnifex (Herbst, 1796) Cardisoma crassum Cardisoma crassum Smith, 1870
Cardisoma rotundum Tuerkayana rotundum (Quoy & Gaimard, 1824) n. comb. (type species)
Discoplax celeste Tuerkayana celeste (Ng & Davie, 2012) n. comb.
Cardisoma hirtipes Tuerkayana hirtipes (Dana, 1851) n. comb.
Discoplax magna Tuerkayana magnum (Ng & Shih, 2014) n. comb.
2) The organisation of thoracic sternites 3 and 4, completely fused without any demarcation, is shared by Leptograpsodes (Figs 1C, D; 3A), Discoplax (Fig. 5A, B), Cardisoma (Fig. 5D, E) and Tuerkayana n. gen. (Fig. 5G, H, J, K, M, N).
3) The presence of a bridge at level of sternal suture 6/ 7 in Leptograpsodes (Figs 1D, E; 3A), very thick in Discoplax (Fig.5B, C), less developed in Cardisoma (Fig. 5E, F, C. guanhumi) (see Ng & Guinot 2001: fig. 3A-C, C. guanhumi, C. carnifex and C. armatum, respectively), in Tuerkayana hirtipes n. comb., and in T. aff. hirtipes (Fig. 5H, I), T. celeste n. comb. (Fig. 5K, L), T. magnum n. comb. (Fig. 5N, O), and T. rotundum n. comb.
4) The genital disposition is similar in Leptograpsodes (Figs 1E; 3B), Discoplax (Fig. 5C), Cardisoma (Fig. 5F) and Tuerkayana n. gen. (Fig. 5I, L, O): the male gonopore, far from suture 7/8, occupies a posteriormost location in relation to sternite 8; it is close to P5 coxo-sternal condyle; the penis emerges just above this condyle, its proximal portion passing between sternite 7 and sternite 8. In T. magnum n. comb. (Fig. 5O) the gonopore is shortly separated from P5 condyle, the sternite 7 joining sternite 8 (a similar short joining is an individual variation observed in T. rotundum n. comb.). In contrast, the male gonopore is quite distant from the P5 coxa in other gecarcinids, see below, Second gecarcinid subclade.
5) A similar stridulatory apparatus is shared by Leptograpsodes and Discoplax: in both sexes, pars stridens formed by the suborbital ridge and plectrum on the inner margin of cheliped merus, showing as distinct, demarcated, whitish ridge in Leptograpsodes (Fig. 2C, D) (at least up to some certain size) and as thickened ridge closer to the merus margin in Discoplax (Fig. 11A); these structures are absent in Cardisoma and Tuerkayana n. gen.
The closest gecarcinid genus to Leptograpsodes is Discoplax with which it shares a wide, practically flat thoracic sternum, in the same plane (without inclination in the posterior portion, so the P1-P5 coxae are at a similar level), and a wide, not deeply hollowed sterno-pleonal cavity. Despite these similarities, there is no doubt that Leptograpsodes is not a gecarcinid. A main distinctive feature is the shape of sternite 8: weakly developed and unexposed medially in Leptograpsodidae n. fam., and developed medially in all Gecarcinidae, except for Gecarcoidea, see below. The thoracic sternum of Leptograpsodes and Discoplax is very wide, whereas it is narrower in Cardisoma and Tuerkayana n. gen. The sterno-pleonal cavity is broad, not deeply hollowed in large-sized Leptograpsodes, narrower and deeper in Cardisoma and Tuerkayana n. gen.
The current classification of Gecarcinidae does not reflect the existence of the two main subclades, supported by the congruence of morphological, larval and genetic data. Establishment of two subfamilies is strongly required but would not be appropriate in the present paper in respect of the project announced in Ng et al. (2008: 214).
description: Published as part of Guinot, Danièle, Ng, Ngan Kee & Rodríguez Moreno, Paula A., 2018, Review of grapsoid families for the establishment of a new family for Leptograpsodes Montgomery, 1931, and a new genus of Gecarcinidae H. Milne Edwards, 1837 (Crustacea, Decapoda, Brachyura, Grapsoidea MacLeay, 1838), pp. 547-604 in Zoosystema 40 (26) on pages 564-568, DOI: 10.5252/zoosystema2018v40a26, http://zenodo.org/record/4336858