Guitonia leimomi, Jr, Robert Murray Lasley, Mendoza, Jose Christopher E. & Ng, Peter K. L., 2010

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, Zootaxa 2684, pp. 1-13 : 9-12

publication ID	https://doi.org/ 10.5281/zenodo.199403
DOI	https://doi.org/10.5281/zenodo.6209917
persistent identifier	https://treatment.plazi.org/id/03B987EC-FFE7-3D25-70CB-C883FB922A00
treatment provided by	Plazi
scientific name	Guitonia leimomi
status	sp. nov.

Treatment

Guitonia leimomi View in CoL n. sp.

( Figs. 1 View FIGURE 1 A, B, 3A, E, F, 4)

Material Examined. Holotype: male, 15.5 × 9.7 mm ( ZRC 2010.0277), cave wall, 2–9 m, South Kona, island of Hawaii, Hawaiian Is., coll. Gustav Paulay, 2002.

Diagnosis. Anterolateral margin with teeth broad at base, spiniform. Anterior regions of carapace lined with high rows of basally fused granules. Corneas, eyestalks greatly reduced. Area lateral to orbits with 2 granular ridges linking at level of exorbital angle, first anterolateral tooth, enclosing small, depressed area. Frontal margin straight, median notch relatively small. Chelae subequal, nearly homomorphic; dactylus of major chela without enlarged subproximal tooth; fixed finger, dactylus of minor chela smooth. Ambulatory legs relatively short, stout; distal end of merus of fourth ambulatory leg not reaching last anterolateral tooth when apposed against carapace. Male telson subtriangular. G1 moderately stout; proximal half nearly straight; distal half sigmoid, twisted 180° on long axis, curving laterally then medially, tip pointing dorsomedially; with lateral flange; inner surface of tip hollowed, cup-shaped, outer surface pointed with rounded tip, elongate, concave.

Description. Carapace ( Fig. 1 View FIGURE 1 A) broader than long, transversely ovate, all regions granular; 1M to 1F depressed; 1F with anterior disjunct transverse row of conjoined granules; 2F with borders undefined; 1M with anterior, elevated row of transverse conjoined granules, lower, shorter, posterior row or rows, border between 1M, 2M indistinct; 2M with several transverse rows of conjoined granules, single granules, partial longitudinal division on anterior half, external branch wider than internal with 1 row of granules higher along anterior border, borders demarcated; 3M, 4M demarcated; 1L with border undefined; regions 1L, 2L, 3L without borders, with 3 transverse rows of conjoined granules, 1 anterior, 2 posterior; 4L demarcated anteriorly with diagonal furrow; 5L, 6L combined, lined with transverse rows of conjoined granules angled slightly towards anterior, anterior rows more elevated; 1R undefined; border between 2R, 3R marked by slight furrow; 1P slightly elevated; 2P undefined; posterior border with transverse furrow followed by transverse row of granules, then unarranged granules; anterior carapace granules higher, more robust, decreasing in size posteriorly.

Front ( Fig. 1 View FIGURE 1 B) about 0.25 times carapace width, advanced over arc of anterolateral margins, bilobed; rim sinuous, curving anteriorly to meet at median V-shaped cleft, lined with minute granules. Medial recessed pit between border, incomplete row of transverse conjoined granules of F1. Front separated from orbital margin by recessed pit. Eyes greatly reduced, cornea pigmented, eyestalks granular. Orbits small, parallel to front; supraorbital margin granular, projecting at junction with recessed pit; infraorbital margins granular, more or less straight. Area lateral to orbits with upper, lower granular ridges linking at level of exorbital angle, first anterolateral tooth, enclosing small, depressed area; lower ridge comprising 3 robust suborbital teeth. Suborbital, pterygostomial, subhepatic regions granular. Epistome granular, transversely depressed, medial sulcus extending from posterior margin to anterior margin, with medial notch; posterior margin concavely arched from medial sulcus until suture 2/3 distance to junction with pterygostomial region, with flattened convex arches laterally. Basal antennal segment rectangular, filling orbital hiatus; antennal flagellum greater than twice width of orbit; antennules folding transversely. Endostome without distinct longitudinal ridges. Postorbital region with slight indication of marginal ridge connecting to first anterolateral tooth. Anterolateral margins arcuate, with 4 distinct teeth roughly equal in size; first tooth blunt; second to fourth broadly triangular with acute tips, curving anteriorly, tooth 4 slightly smallest; teeth granular, separated by denticles. Merus of third maxilliped ( Fig. 4 View FIGURE 4 A) granular, subquadrate, anteroexternal angle slightly produced, anterior margin concave; with depression near insertion of carpus; median length approximately half that of ischium; ischium granular with longitudinal medial sulcus; internal margin with depressed lip, thin setae lining internal border of lip, continuing to junction with basis, separated from basis by slight suture; exopod granular.

Surface of thoracic sternum ( Fig. 3 View FIGURE 3 A) granular. Sternites 1, 2 completely fused into triangular plate, separated from sternite 3 by deep transverse suture; suture between sternites 3, 4 deep laterally, only slightly indicated medially; sternite 4 with distinct median longitudinal line; suture between sternites 4, 5 distinct; suture between sternites 5, 6 slightly indicated; suture between sternites 6, 7 deep; sternite 8 small, hidden behind abdomen. Abdominal cavity deep, sternal push button midway between anterior, posterior sutures of sternite 5, telson almost reaching imaginary line joining cheliped coxae.

Chelipeds ( Fig. 3 View FIGURE 3 E, F) similar, subequal. Fingers with tips crossing, about as long as palm. Dactylus curved ventrally, posteriorly; dorsal surface granular proximally, smooth with punctuations distally, with two longitudinal grooves fading distally; anterior, posterior surfaces each with longitudinal row of punctuations; cutting edge of major chela with 3 small teeth interdigitating with 3 teeth of fixed finger, denticles lining margin to tip; minor chelae with denticles along cutting edge. Fixed finger with teeth, denticles lining margin to upturned tip, with anterior, posterior longitudinal row of punctuations, less defined row of punctuations near anterior margin of cutting edge. Outer, upper surfaces of propodus granular entirely with distinct dorsal longitudinal groove, lesser inner longitudinal groove; inner, lower surfaces of major chela smooth, ventral margin relatively straight. Carpus granular; dorsal granules larger than ventral, single or clustered, sometimes pointing toward propodus; with groove near dorsal junction with propodus forming collar; inner distal angle with triangular projection. Merus granular; dorsal surface with larger granules; outer margin with few prominent conical granules.

Ambulatory legs relatively long, slender; P3, P4 longest, P4 coxa-to-dactylus length 1.09 times carapace width, P5 shortest. Merus long, fusiform in cross section, length ca. 3.5 times width, granular with sparse simple setae, distal end of merus of fourth ambulatory leg not reaching last anterolateral tooth when apposed against carapace; dorsal edge with row of short spines; ventral surface with row of short spines forking distally, low or indistinct in P4, P5; anterior surface smooth; length approximately equal to length of propodus, carpus combined; not reaching last anterolateral tooth when apposed against carapace. Carpus granular with sparse simple setae; dorsal surface with larger, distally pointing conical granules, absent along posterior longitudinal groove. Propodus granular with sparse, simple setae; granules conical, distally pointing; anterior, posterior surfaces with furrow lacking conical granules. Dactylus long, slender, granular; dorsal, ventral surfaces with short stiff setae; terminates distally in curved chitinous claw.

External surface of male abdomen ( Figs. 3 View FIGURE 3 A, 4B) with sparse, fine setae, 5 discernable somites, including telson. Somite 1 longer at lateral edges with concave distal margin; granules larger laterally. Somite 2 subtrapezoidal; lateral margins proximally convex, distally concave; proximal margin convex; distal margin concave. Somites 3–5 immovably fused, lateral margins concave, sutures indiscernible except laterally between somites 3, 4. Somite 3 with larger granules laterally, minute medially. Somites 4, 5 with minute granules; central region raised. Somite 6 subquadrate, central region slightly raised; telson subtriangular.

G1 ( Fig. 4 View FIGURE 4 C–E) moderately stout; proximal half nearly straight; distal half sigmoid, curving laterally then medially, twisted 180° on long axis, tip pointing dorsomedially; with several long, stout distal setae; ventral, dorsal margins lined with short spines; median groove for G2 ( Fig. 4 View FIGURE 4 F); lateral flange; inner surface of tip hollowed, cup-shaped, outer surface pointed with rounded tip, elongated, concave.

Etymology. The specific epithet leimomi is derived from the Hawaiian words for “pearl” and “necklace,” lei and momi, respectively, alluding to the conjoined rows of granules on the carapace. Used as a noun in apposition.

Distribution. Known so far only from the Hawaiian Is.

Remarks. Guitonia leimomi n. sp., is described based on only one male specimen from the Hawaiian Is. (see also Remarks for Guitonia ). Guitonia leimomi n. sp., differs from both G. troglophila and G. paulayi n. sp., in having anterior regions of the carapace lined with prominent, basally-fused, transverse rows of granules ( Fig. 1 View FIGURE 1 A) (few low or indiscernible anterior basally-fused, transverse rows of granules in G. paulayi n. sp., and G. troglophila , Fig. 1 View FIGURE 1 C, E), and greatly reduced corneas and eyestalks ( Fig. 1 View FIGURE 1 B) (well developed in G. paulayi n. sp., and intermediate in G. troglophila , Fig. 1 View FIGURE 1 D, F). It differs from G. troglophila in having similar, subequal chelae without a basal differentiated tooth on the dactylus of the major chela ( Fig. 3 View FIGURE 3 E, F) (unequal chelae with a differentiated basal tooth in G. troglophila , fig. 3G, H) and narrower, anteriorly pointing anterolateral teeth ( Fig. 1 View FIGURE 1 A) (broader, lower anterolateral teeth in G. troglophila , Fig. 1 View FIGURE 1 E). See remarks for Guitonia and G. paulayi n. sp., regarding interspecific differences.