Guitonia paulayi Jr, Mendoza & Ng, 2010, n. sp.
Creators: name: Jr, Robert Murray Lasley
name: Mendoza, Jose Christopher E.
name: Ng, Peter K. L.
Publisher: name: Zenodo
Year: 2010
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Decapoda
Xanthidae
Guitonia
Guitonia paulayi

description: Guitonia paulayi n. sp.
(Figs. 1 C, D, 2, 3B, C, D)
Material examined. Holotype: male, 11.2 × 7.3 mm (ZRC 2010.0278), under rocks, 8–11 m, Glass Breakwater, Apra Harbor, Guam, Mariana Islands, coll. H. T. Conley, August 1998. Paratypes: 1 male, 10.9 × 7.1 mm (UF 1291), among rocks and dead coral, 3–6 feet, Orote Peninsula east of Neye I., Guam, Mariana Is., coll. H. T Conley, August 1984; 1 male, 10.1 × 6.8, 1 female, 11.4 × 7.3 mm (ZRC 2010.0280), among rocks and silt, 8–20 ft, Agat Bay, N of Alutom I., Guam, Mariana Is., coll. H. T. Conley, 2000; 1 male, 9.2 × 6.3 mm, 1 female, 9.4 × 6.4 mm (UF 26254), among rocks, 15–25 feet, near harbor entrance, Glass Breakwater, Apra Harbor, Guam, Mariana Is., coll. H. T. Conley, 22 August 1984; 2 males, 9.4 × 6.4 mm to 9.5 × 6.7 mm (USNM), among rocks and silt, 8–20 feet, Agat Bay, N of Alutom Island, Guam, Mariana Islands, coll. H. T. Conley, 2000; 1 male, 9.0 × 6.1 mm (UF 1967), among rocks, 15–30 ft, near harbor entrance, Glass Breakwater, Apra Harbor, Guam, Mariana Islands, coll. H. T. Conley, 5 April 2002.
Diagnosis. Anterolateral margin with teeth narrow, spiniform. Anterior regions of carapace with weak rows of basally fused granules. Corneas, eyestalks well developed. Area lateral to orbits lacking granular ridges, without small, depressed area. Frontal margin straight, median notch relatively small. Chelae subequal, nearly homomorphic; fixed finger, dactylus of minor chela smooth. Ambulatory legs relatively long, slender; distal end of merus of fourth ambulatory leg almost reaching last anterolateral tooth when apposed against carapace. Male telson subtriangular with rounded tip. G1 moderately stout; proximal half nearly straight; distal half sigmoid, twisted 90º on long axis, curving laterally then ventrally, pointing ventromedially; tip bifurcate, pointing medially, dorsal tip twisting distally, ventral tip lanceolate, concave toward dorsal tip.
Description. Carapace (Fig. 1 C) broader than long, transversely ovate, granular; 1F with anterior transverse row of granules forming upper rim of front; 2F with borders undefined; depressed from 1M to 2F; 1M with 2 transverse rows of conjoined granules; 2M demarcated, but slightly anteriorly, with faintly marked partial longitudinal division on anterior half, external branch wider than internal, anterior of internal branch fused with 1M; 3M, 4M demarcated; 1L depressed, borders undefined; 2L borders undefined with high anterior row of about 5 transverse, conjoined granules, low posterior row of fewer transverse conjoined granules; 3L with borders undefined except slightly at border with 4L, with row of transverse, conjoined granules intersecting border with 2L; 4L slightly defined, small; 5L demarcated with exception of lateral, posterior borders, with long, transverse row of conjoined granules at anterior border; 6L demarcated slightly at anterolateral border, otherwise undefined; 1R with borders undefined; border between 2R, 3R demarcated; other regions not demarcated; regions granular, sparsely setose; posterior regions with smaller, lower granules.
Front (Fig. 1 D) about 0.25 times carapace width, slightly advanced over arc of anterolateral margins, bilobed; anterior margin doubly rimmed; lower rim bilobed, slanting ventromedially, lobes convex anteriorly, joining at medial V-shaped cleft, with low granules; upper rim formed by row of conjoined granules; medial recessed pit between upper, lower rims; separated from orbital margin by recessed pit. Eyestalks granular. Orbits slanting ventrolaterally; supraorbital margin granular, produced adjacent to recessed pit; infraobital margin granular, projecting at inner, outer angles, forming teeth. Suborbital, pterygostomial, subhepatic regions granular. Epistome transversely depressed, medial sulcus extending from posterior margin halfway to anterior margin; posterior margin with concave arches on either side of medial sulcus until notches 2/3 distance to junction with pterygostomial region. Basal antennal segment rectangular, filling orbital hiatus, antennal flagellum greater than twice width of orbit; antennules folding transversely. Endostome without distinct longitudinal ridges, row of minute granules along anterior border. Anterolateral margins arcuate, with 4 distinct teeth; margin anterior to tooth 1 poorly defined; first tooth tuberculiform; second through fourth acute, narrow, curving anteriorly; teeth 1, 4 small, 2, 3 larger; teeth separated by 3 to 5 marginal denticles. Outer surface of third maxilliped granular; merus (Fig. 2 A) granular, subquadrate, anteroexternal angle slightly produced, anterior margin sinuous, median length less than half that of ischium, with depression near insertion of carpus; ischium subrectangular with longitudinal medial sulcus; internal margin with depressed lip, thin setae lining internal border of lip, separated from basis by distinct suture; exopod granular distally, anteroexternal angle projecting.
Surface of thoracic sternum (Fig. 3 B) granular. Sternites 1, 2 completely fused into triangular plate; suture between sternites 2, 3 distinct; suture between sternites 3, 4 deep laterally, gradually less distinct medially; sternite 4 with faint, shallow diagonal groove medial to condyle of chelipeds; sutures between sternites 4, 5, 5, 6 distinct; suture between sternites 6, 7 deep; sternite 8 small, hidden behind abdomen. Abdominal cavity deep, press-button on sternite 5, nearer to suture with sternite 4, abdomen reaching beyond imaginary line joining posterior edge of cheliped coxae.
Chelipeds (Fig. 3 C, D) subequal. Major chela more robust, with more pronounced teeth, varying in size, placement, sometimes with robust, differentiated basal tooth on dactylus, otherwise similar to minor chela; ventral margin smooth with punctuations, sinuous, proximal half convex; fingers with tips crossing; margin of fixed finger lined with teeth or denticles of varying size, placement, proximal tooth usually bicuspid; tip upturned. Outer surface of chelae with dorsoproximal half granular; ventroproximal half smooth with punctuations; granulation ending abruptly in diagonal line. Dactylus usually with 2 or 3 large basal teeth, first of which is often differentiated. Propodus with dorsal surface granular with two narrow grooves, strong basally, fading distally; more distinct in minor chela; palm smooth. Carpus granular on dorsal, external surfaces with triangular projection on inner angle. Merus granular dorsally with smaller granules anteriorly, smooth ventrally.
Ambulatory legs relatively long, slender, P2 to P3 longer than P5, ratio of P4 (coxa to dactylus length) to carapace width is 1.29. Merus subrectangular, long, length ca. 3.5 times width, distal end of merus of fourth ambulatory leg almost reaching last anterolateral tooth when apposed against carapace; anterior, posterior margins lined with low laterally pointing spines, spines less distinct ventrally on P5; with sparse, simple or plumose setae; dorsal, ventral surfaces with minute granules; length equal or greater than length of propodus, carpus combined; almost reaching last anterolateral tooth when apposed against carapace. Anterior margin of carpus with short, laterally pointing spines; anterior surface with granules, spines, sparse setae; anterodorsal surface with longitudinal furrow; ventral surface smooth. Propodus with scattered setae, granular, with weak anterior, posterior longitudinal furrows. Dactylus long, slender, straight; anterior, posterior with scattered, robust simple setae, short spines; small tip pointed, slightly curved.
External surface of male abdomen (Figs. 2 B, 3B) with sparse, fine setae, with 5 discernible somites, including telson. Somite 1 longer at lateral edges with concave distal margin. Somite 2 subtrapezoidal with small granules; proximal margin convex; distal margin concave. Somites 3–5 immovably fused, lateral margins concave, smooth, sutures indiscernible except laterally between sternites 3, 4; small lateral notch between somites 4, 5; central region raised. Somite 6 subquadrate, central region slightly raised, anterolateral angles slightly raised. Telson subtriangular with rounded tip.
G1 (Fig. 2 C–E) moderately stout; proximal half nearly straight; distal half sigmoid, curving laterally then ventrally, twisted 90º on long axis, pointing ventromedially; with several long, stout distal setae; ventral, dorsal margins lined with short spines; groove for G2 (Fig. 2 F) dorsal in position; with distal ventral ridge; tip bifurcate, pointing medially, dorsal tip twisting distally, ventral tip lanceolate, concave toward dorsal tip.
Vulva of mature females circular, moderate in size, in middle of sternite 6; aperture opens medially; operculum papillate.
Etymology. The species is named for the distinguished invertebrate biologist Gustav Paulay, who mentored the first author.
Distribution. Known only from Guam.
Remarks. Guitonia paulayi n. sp., is only known from Guam, Mariana Islands, where it is apparently common among coral rubble and rocks. It shares more similarities with G. leimomi n. sp., than G. troglophila, which is not surprising considering G. troglophila is only found in anchialine caves in the Galápagos Is., whereas G. leimomi n. sp., and G. paulayi n. sp., occur in the Western Pacific, on the other side of the East Pacific biogeographic barrier (Paulay 1997) (see also Remarks for Guitonia). Guitonia paulayi n. sp., can be distinguished from G. troglophila and G. leimomi n. sp., by its relatively smaller, more acute, anterior pointing anterolateral teeth, the first of which is reduced to a small knob (Fig. 1 C) (relatively wider, more triangular anterolateral teeth, the first of which is complete in G. troglophila and G. leimomi n. sp., Fig. 1 A, E) and its fully developed corneas and eyestalks (Fig. 1 D) (reduced corneas and eyestalks in G. troglophila and G. leimomi n. sp., Fig. 1 B, F). Furthermore, it can be distinguished from G. troglophila by its higher transverse, conjoined rows of granules on the carapace, especially evident on regions 1M and 2L (Fig. 1 C) (low or indiscernible transverse conjoined rows in G. troglophila, Fig. 1 E) and double rimmed front formed by a row of granules on the anterior border of the carapace region F1 (Fig. 1 D) (a single rimmed front in G. troglophila, Fig. 1 F) (Garth & Iliffe 1992). Guitonia paulayi n. sp., can be distinguished from G. leimomi n. sp., by having a merus of the third maxilliped with a sinuous anterior margin (Fig. 2 A) (arched in G. leimomi, Fig. 4 A), fewer and lower conjoined rows of granules on the carapace (Fig. 1 C) (numerous raised, transverse, conjoined granules in G. leimomi n. sp., Fig. 1 A), an abdominal telson with a relatively broader and more rounded tip (Fig. 2 B) (more triangular telson in G. leimomi n. sp., Fig. 4 B), and a male G1 with the distal half twisted 90° on the long axis and a narrower, medially pointed tip (Fig. 2 C–E) (a male G1 with the distal half twisted 180° and a broader, laterally pointed tip, Fig. 4 C–E).
description: Published as part of Jr, Robert Murray Lasley, Mendoza, Jose Christopher E. & Ng, Peter K. L., 2010, Two new species of Guitonia Garth & Iliffe, 1992 (Crustacea: Decapoda: Brachyura: Xanthidae) from the central and western Pacific Ocean, pp. 1-13 in Zootaxa 2684 on pages 4-9, DOI: 10.5281/zenodo.199403