Lithodidae, Samouelle, 1819

McLaughlin, P. A., 2003, Illustrated keys to families and genera of the superfamily Paguroidea (Crustacea: Decapoda: Anomura), with diagnoses of genera of Paguridae, Memoirs of Museum Victoria 60 (1), pp. 111-144 : 114-115

Key to genera of Lithodidae

1. Abdomen usually soft, membranous, sac-like; abdominal tergites 3–5 not fully calcified ( Figs 1i , 9a–d ) rostral process short, broad, triangular, not usually overreaching distal margins of corneas....................... 2

— Abdomen generally firm, at least partially calcified, not sac-like; abdominal tergites 3–5 usually well calcified ( Figs 9f–k ), sometimes with median areas membranous; rostral process well-developed, prominent, truncate or spiniform ( Fig. 8f, h ), overreaching distal margins of corneas ( Fig. 3b )............................. 6

2. Tergite of abdominal somite 2 divided into median, paired lateral and paired marginal plates ( Figs 9a, b, d, e, h ). 3

— Tergite of abdominal somite 2 divided into paired lateral and marginal plates, median plate virtually nonexistent ( Fig. 9c )................ Placetron Schalfeew, 1892

3. Median plate of abdominal somite 2 well calcified or with cluster of calcified granules ( Figs 9a, b )............ 4

— Median plate of abdominal somite 2 membranous ( Fig. 9d ) ........................................... 5

4. Carapace well calcified, dorsal surface and margins armed with numerous subequal spines; rostral process with dorsal and lateral spines....... Acantholithodes Holmes, 1895

— Carapace weakly calcified, dorsal surface lacking spines but setose or pubescent; rostral process simple, lacking dorsal and lateral spines ( Fig. 1i )......................................... Hapalogaster Brandt, 1850

5. Surface of carapace covered with squamose prominences, chelipeds tuberculate ( Fig. 6p ).......................................... Oedignathus Benedict, 1895

— Surface of carapace and chelipeds covered with transverse ridges or crests ( Fig. 6q )..... Dermaturus Brandt, 1850

6. Carapace nearly smooth, unarmed, broader than long and completely covering ambulatory legs when legs are drawn in against body ( Figs 1h , 8h ); rostral process broad, compressed, distally truncate ( Fig. 1h , 8h ).................................... Cryptolithodes Brandt, 1848

— Carapace armed with granules, tubercles or spines, not broader than long and not completely covering ambulatory legs when legs are drawn in against body; rostral process variable in shape, but not compressed and distally truncate...........................................7

7. Sternite of somite XI (pereopods 2) with deep longitudinal medial groove or pit ( Fig. 2n )................... 8

— Sternite of somite XI (pereopods 2) without deep longitudinal medial groove or pit................ 10

8. Tergite of abdominal somite 2 subdivided into median and paired lateral and marginal plates ( Figs 9a, b, d, e, h ). 9

— Tergite of abdominal somite 2 usually subdivided into median and paired marginal plates ( Fig. 9i ), rarely undivided................. Lithodes Latreille, 1806

9. Tergites of abdominal somites 3–5 with only spinulose or spiniform nodules calcified ( Fig. 9e ) in males; females with lateral plates of left side well delineated; antennal acicle usually absent................................... Neolithodes A. Milne-Edwards and Bouvier, 1894

— Tergites of abdominal somites 3–5 with lateral plates clearly delineated in both sexes, median plate with nodular calcification, accessory marginal plates well developed ( Figs 9h, i ); antennal acicle present........................................ Paralithodes Brandt, 1848

10. Tergite of abdominal somite 2 subdivided into 3–5 well calcified plates ( Figs 9 e, f, h, i )................. 11

— Tergite of abdominal somite 2 undivided ( Figs 9g, j, k )............................................12

11. Tergite of abdominal somite 2 subdivided into 3 plates (median and paired laterals) ( Fig. 9f )..................................... Phyllolithodes Brandt, 1848

— Tergite of abdominal somite 2 subdivided into 5 plates (median, paired lateral and marginal) ( Figs 9e, h )........................... Rhinolithode s Brandt, 1848

12. Rostral process thick, non-spiniform, hammer-shaped ( Fig. 1j ); antennal acicle small, rudimentary; tergites of abdominal somites 4 and 5 with median plates irregularly calcified............. Sculptolithodes Makarov, 1934

— Rostral process more or less spiniform; antennal acicle well-developed; tergites of abdominal somites 4 and 5 with median plates regularly and entirely calcified ( Figs 9f, g, j, k ) .................................... 13

13. Rostral process formed by anterior process (basal spine) and dorsal spine or granule ( Fig. 8g )..................................... Glyptholithodes Faxon, 1895

— Rostral process formed by anterior process (basal spine) and at least 1 pair of dorsal spines ( Fig. 8f )........ 14

14. Lateral tergal plates of abdominal somite 3 entire ( Figs 9f, j ); antennal acicle moderately spinulose; walking leg 3 always equal to or longer than carapace width.................................. Paralomis White, 1856

— Lateral tergal plates of abdominal somite 3 each with small accessory plates sundered anteromedially ( Figs 9g, k ); antennal acicle extremely spinulose; walking leg 3 never equal to or longer than carapace width.................................... Lopholithodes Brandt, 1848

Figures

Figure 1. Morphological diversity among members of the Paguroidea. a, b, Coenobitidae, c, Pylochelidae; d–g, Diogenidae; h–k, Lithodidae, l–o, Paguridae, p, q, Parapaguridae: a, Birgus latro Leach; b, Coenobita clypeatus (Fabricius); c, Trizocheles spinosus (Henderson); d, Allodardanus bredini Haig and Provenzano; e, Dardanus venosus (H. Milne Edwards); f, Clibanarius arethusa De Man; g, Calcinus tibicen (Herbst); h, Cryptolithodes sitchensis Brandt; i, Hapalogaster dentata (De Haan); j, Sculptolithodes derjugini Makarov; k, Lithodes murrayi Henderson; l, Labidochirus splendescens (Owen); m, Propagurus gaudichaudi (H. Milne Edwards); n, Ostraconotus spatulipes A. Milne–Edwards; o, Porcellanopagurus edwardsi Filhol; p, Tylaspis anomala Henderson; q, Probeebei mirabilis Boone. [a, f after Alcock, 1905; b, from Chace and Hobbs, 1969; c, k, p, from Henderson, 1888; d, e, g, after Chace et al. 1985; h, from Makarov, 1938; i, j, from Vinogradov, 1950; l from McLaughlin, 1974; m, from Benedict, 1901 as Eupagurus patagonensis Benedict; n, after A. Milne-Edwards and Bouvier, 1893; o, after Forest, 1951; q, from Wolff, 1961; not to scale.]

Figure 2. Bases and paired basis-ischium of maxilliped 3: a, Coenobitidae – Coenobita clypeatus (Fabricius); b, Diogenidae – Clibanarius vittatus (Bosc); c, Pylochelidae – Mixtopagurus paradoxus A. Milne-Edwards; d, Pylojacquesidae – Pylojacquesia colemani McLaughlin and Lemaitre; e, Parapaguridae – Parapagurus pilosimanus Smith; f, Paguridae – Pagurus pollicaris Say; g, reduced teeth on crista dentata of ischium, Scopaeopagurus megalochirus McLaughlin and Hogarth. Antennular and antennal flagella. h–j, antennular flagella: h, Coenobitidae; i, Pagurus imafukui McLaughlin and Konishi; j, generalised flagella of Diogenidae, Paguridae and Parapaguridae; k, antennal flagellum with paired ventral setae. Thoracic sternites and coxae of pereopods: l, Pylojacquesia colemani McLaughlin and Lemaitre; m, generalised Paguridae; n, Lithodes aequispinus Benedict (sternites X and XI only; groove and pit of sternite XI indicate by arrow). Abbreviations: act = accessory tooth (teeth) indicat- ed by arrows; ap = anterior portion; C 1–5 = coxae of pereopods 1–5; gp = gonopore; mh = membranous hinge; pp = posterior portion. [a–f, l, from McLaughlin and Lemaitre, 2001c; g, from McLaughlin and Hogarth, 1998; h, from McLaughlin and Dworschak, 2001; i from McLaughlin and Konishi, 1994; j, from Forest et al. 2000; k, from McLaughlin and Haig, 1996b, m, adapted from McLaughlin, 1974; not to scale]

Figure 3. Basic morphology: a, diagrammatic pagurid (whole animal, dorsal view); b, diagrammatic lithodid (whole animal, dorsal view). Cephalothorax or shield, with or without cephalic appendages: c–h Pylochelidae; i, Diogenidae; j, Pylojacquesidae; k–m Paguridae. c, Pylocheles; d, Trizocheles; e, Cheiroplatea; f, Pomatocheles; g, Parapylocheles; h, Cancellocheles; i, Diogenes; j, Pylojacquesia; k, Porcellanopagurus; l, Solitariopagurus; m, Hemipagurus. Abbreviations: aa = antennal acicle; ant. = antenna; antu = antennule; c, cornea; car = carpus; cg = cervical groove; dac = dactyl; ff = fixed finger; irp = intercalary rostral process; la = linea anomurica; lf ch = left cheliped; lf ur = left uropod; lp = lateral projection; lt = linea transversalis; mer = merus; oa = ocular acicle; op = ocular peduncle; P2–5 = pereopods 2–5; pcl = posterior carapace lobe; pcme = posterior carapace median element; pl3–5 = pleopods 3–5; plm = palm; pmp = posterior median plate; pop = postocular projection; pro = propodus; r = rostrum or rostral lobe; rt ch = right cheliped; s = shield; sl1–3 = shield lobes 1–3; t6 = abdominal tergite 6; tel = telson. [a, b, adapted from Sandberg and McLaughlin, 1998; c, d from Forest et al. 2000; e–h, from Forest, 1987; i, from McLaughlin and Clark, 1997; j, from McLaughlin and Lemaitre, 2001c; k, l, from McLaughlin, 2000; m, from McLaughlin, 1997 (as Catapagurus); not to scale.]

Figure 6. Chelipeds: a, left chela of Ciliopagurus (mesial view) showing stridulating mechanism (indicated by arrows); b, left chela of Allodardanus (mesial view) lacking stridulating mechanism; c, left chela and carpus of Ciliopagurus (lateral view); d, chelae of Cancellus togeth- er forming operculum; e, left carpus and chela of Aniculus; f, left chela and carpus of Isocheles (dorsal view), with dactyl opening horizontally (as indicated by arrow), g, left chela and carpus of Loxopagurus (dorsolateral view) with dactyl opening vertically (as indicated by arrow); h, right chela and carpus of Paragiopagurus (dorsal view) with dactyl opening obliquely (as indicated by arrow); i, right chela of Pylojacquesia; j, right chela of Xylopagurus; k, right chela of Bathypaguropsis; l, right chela of Lophopagurus (Australeremus); m, right chela of Rhodochirus; n, left chela of Lophopagurus (Lophopagurus); o, right carpus and chela of Goreopagurus (lateral view); p, right carpus and chela of Oedignathus (mesial view); q, right carpus and chela of Dermaturus (mesial view). [a, c, from Forest, 1952; b, after Haig and Provenzano, 1965; d, after Mayo, 1973; e, from McLaughlin and Hoover, 1995; f, g, from Forest and de Saint Laurent, 1968; h, from Lemaitre, 1996; i, from McLaughlin and Lemaitre, 2001c; j, from Lemaitre, 1995; k, from McLaughlin, 1994; l, n, from McLaughlin and Gunn, 1992; m, from Williams, 1984; o, from McLaughlin and Haig, 1995; k, l, after Vinogradov, 1950; not to scale].

Figure 8. Additional morphological characters: a, c, shield with Y-shaped posterior groove; b, shield without Y-shaped posterior groove; d, last thoracic somite and abdomen of Xylopagurus (dorsal view); e, multifid ocular acicles; f, Lithodes rostral spine complex; g, dorsal and ventral rostral spines of Glyptolithodes; h, Cryptolithodes (ventral view) with carapace covering body and appendages; i, rostrum with epirostral spine (lateral view); j, symmetrical uropods and posterior portion of abdominal tergite 6, plus telson (dorsal view) k, right antennal peduncle with hooked spine (indicated by arrow) on lateral margin of segment 1; l, shield of Typhlopagurus showing spinose ocular and antennal acicles and lack of ocular peduncles; m, parapagurid epistome and labrum. Abbreviations: apr = anterior rostral process; ds = dorsal spine(s); es = epistomial spine; ls = labral spine; vs = ventral spine; 6 indicates abdominal tergite 6. [a, from McLaughlin and Hoover, 1996; b, from Forest and de Saint Laurent, 1968; c, from Forest and McLaughlin, 2000; d, from Lemaitre, 1995; e, McLaughlin and Murray, 1990; f, from Vinogradov, 1950; g, after Haig, 1974; h, from Makarov, 1938; i, from McLaughlin, 1997; j, from McLaughlin and Lemaitre, 1993; k, from McLaughlin, 1981; l, from de Saint Laurent, 1972; m, after Lemaitre, 1989; not to scale].

Figure 9. Lithodid abdominal tergites: a, Acantholithodes tergites 1 and 2, tergites 3–6 and telson; b, Hapalogaster tergites 1–3; c, Placetron tergites 1 and 2, tergites 3–6 and telson, showing female asymmetry in tergites 3–5; d, Oedignathus tergites 1–3; e, Neolithodes tergites 1 and 2, tergites 3–6 and telson; f, Phyllolithodes tergites 1 and 2, tergites 3–6 and telson; g, Lopholithodes tergite 1+2, tergites 3–6 and telson; h, Paralithodes tergites 1 and 2, tergites 3–6 and telson; i, Lithodes tergites 1 and 2, tergites 3–6 and telson; j, Paralomis tergite 1+2, tergites 3–6 and telson; k, Cryptolithodes tergite 1+2. tergites 3–6 and telson. Abbreviations: am = accessory marginal plates; ap = accessory plate; la = lateral plate, m = marginal plate; M = median plate; t = telson; tergites are numbered 1–6. [a–i, k from McLaughlin and Lemaitre, 2001a.; j adapted from Macpherson, 1988; not to scale].