Calappa exanthematosa Alcock & Anderson, 1894

Ng, Peter K. L., Lai, Joelle C. Y., Ghotbeddin, Negar & Safaie, Mohsen, 2011, Calappa exanthematosa Alcock & Anderson, 1894, as a valid species of box crab from the Indian Ocean (Crustacea: Decapoda: Calappidae), Zootaxa 3042, pp. 1-14 : 2-13

Calappa exanthematosa Alcock & Anderson, 1894 , stat. nov.

( Figs. 1 , 2 , 4 , 5 B, 6B, 7B, 8C, D, 9D–F)

Calappa exanthematosa Alcock & Anderson, 1894: 177 ; Alcock & Anderson 1895: pl. 15 figs. 1, 1a; Alcock 1896: 146. Calappa japonica — Sankarankutty & Subramanian 1976: 21; Jones 1989: 133; Galil 1997: 301, figs. 10d, 13d, 15; Davie 2002: 127 (part); Jones & Morgan 2002: 143; Poore 2004: 327, figs. 96d, 97d; Spiridonov & Apel 2007: 2853, fig. 1A, B; Ng et al. 2008: 48 (list) (part) (not Calappa japonica Ortmann, 1892 ).

Calappa cf. pustulosa — Türkay 1986: 150 (not Calappa pustulosa Alcock, 1896 ).

Material examined. INDIA: Bay of Bengal, 1 male (lectotype of Calappa exanthematosa Alcock & Anderson, 1894 , designated by Lai & Ng 2006) (80.5 × 58.4 mm) (NHM 1896.9.8.8, donated by Indian Museum), 13˚01’06”N, 90˚36’56” E, 107 fms (= 196 m), Bay of Bengal; 1 male (46.4 × 35.3 mm) ( ZMUC) (Indian Museum label 9/1899), west coast of Indian Subcontinent, 17˚27’N, 71˚41’E, 56‒58 fathoms. PAKISTAN: 1 male (52.6 × 39.5 mm) ( ZMUC Cru 1846), 24˚50’N, 61˚52’E, Mekran, 135‒148m, coll. P. Hansen, 25 November 1963. IRAN: 1 male (114.0 × 79.0 mm), 1 female (90.0 × 64.0 mm) ( ZUTC Brach. 1826), 25˚08’–25˚10’N, 60˚27’‒60˚59’E, 16–23 m, Chabahar Bay, Gulf of Oman, coll. N. Ghotbeddin, 16 August 2009; 1 male (107.0 × 72.0 mm), 1 female (101.0 × 74.0 mm) ( ZUTC), 25˚15’–25˚20’N, 59˚10’–60˚20’E, 40–46 m, Meidani, Gulf of Oman, coll. N. Ghotbeddin, 15 September 2009; 1 female (97.0 × 68.0 mm) ( ZRC 2011.0780), 1 female (95.0 × 63.0 mm) ( ZUTC), 25˚00’–25˚06’N, 61˚06’–61˚11’E, 19–25 m, Beris, Gulf of Oman, coll. N. Ghotbeddin, 19 August 2009; 2 females (87.0 × 67.0 mm, 90.0 × 69.0 mm) ( ZUTC), 24˚51’–24˚59’N, 59˚10’–60˚20’E, 13–18m, Pasabandar, Gulf of Oman, coll. N. Ghotbeddin, 19 August 2009; 1 male (136.0 × 94.0 mm) ( ZRC 2011.0779), 1 female (112.0 × 78.0 mm) ( ZMSB), 25˚20’–25˚27’N, 58˚42’–58˚55’E, 20–35 m, Jask, Gulf of Oman, coll, M. Safaei, 13–16 December 2010.

Comparative material. Calappa japonica Ortmann, 1892 : TAIWAN: 1 male (138.8 × 97.8 mm) ( ZRC 1999.0726) South Taiwan: Kaohsiung County, Tungkang Fish Port coll. P. K. L. Ng, May 1999; 2 males (130.6 × 93.7 mm, 140.7 × 98.8 mm), 1 female (145.2 × 104.6 mm) ( ZRC 2001.0002) South Taiwan: Kaohsiung County, Tungkang Fish Port coll. P.K.L. Ng, 7 November 2000; 1 male (145.3 × 102.4 mm) ( ZRC 1998.0204) North-East Taiwan, I-Lan County, Tai-Chi Fish Port, commercial inshore trawlers about 100– 400m. coll. P. K. L. Ng, 3–4 August 1996. PHILIPPINES: 1 male (49.7 × 40.0 mm) ( ZRC 2001.0346), off Panglao, Bohol, Philippines, coll. local fishermen, December 2000; 1 male (168.8 × 105.8 mm) ( ZRC), Balicasag Island, Panglao, Bohol, Visayas, Philippines, in tangle nets, coll. local shell fishermen, 28 November 2001; 1 male (73.2 × 57.2 mm), 2 females (32.9 × 28.0 mm, 50.8 × 41.5 mm) ( ZRC), Balicasag Island, Panglao, Bohol, Visayas, Philippines, in tangle nets, coll. local shell fishermen, 28 November 2001; 1 male (47.9 × 39.2 mm) ( ZRC), Balicasag Island, Panglao, Bohol, Visayas, Philippines, in tangle nets, 200‒300 m, coll. local shell fishermen, June 2002; 1 male (68.3 × 52.3 mm), 1 female (46.2 × 37.0 mm), 2 juveniles (larger 21.5 × 18.2 mm) ( ZRC 2002.0464), 1 male (carapace length 36.7 mm, sides damaged) ( ZRC 2002.0465), Balicasag Island, Panglao, Bohol, Visayas, Philippines, from tangle nets, coll. local fishermen, June–July 2002; 1 juvenile male (31.2 × 25.9 mm) ( ZRC 2006.0112), Balicasag Island, Panglao, Bohol, Visayas, Philippines, from tangle nets, coll. local fishermen, June 2004; 1 female (100.1 × 74.6 mm) ( ZRC 2006.0113), Balicasag Island, Panglao, Bohol, Visayas, Philippines, from tangle nets, coll. local fishermen, 29 May 2004. VANUATU: 1 female ( ZRC 2009.0436), West Malo island, Vanuatu, station AT64, 15˚39.6’S 167˚01.9’E, 249‒252 m, coll. SANTO Expedition, 4 October 2006. Calappa africana Lai & Ng, 2006 : Holotype male (109.7 × 81.2 mm) ( USNM 268804), station 442, Somalia, off northeast coast. 9º33’N 50º59’E, trawled at 70‒80m depth, coll. R/V Anton Bruun cruise no 9, 16 December 1964; paratype female (105.8 × 80.5 mm) ( ZRC 2006.0109), South Africa, Eastern Cape, Port Elizabeth, Bay World, off Kenton, coll. S. Warren, June 2004; 1 male (126.3 × 84.2 mm) ( RMNH 30335), Kenya, Mombasa, coll. A. J. Bruce, 1974.

Diagnosis. Carapace with dorsal surface strongly convex, anterior two-thirds covered with large, round submammillate tubercles, posterior third relatively smooth; with transverse row of low tubercles just before posterior margin of clypeiform process, forming shallow groove covered with numerous small granules; longitudinal gastrocardiac grooves deep, posterior parts spaced relatively close to each other. Pterygostomian lobe at end of posterior margin of epistome with relatively narrow inner oblique longitudinal groove. Anterolateral margin with 11 or 12 blunt, rounded unevenly sized tubercles; last 6 or 7 tubercles stronger; posterolateral margin of clypeiform expansion with 7 (rarely 8) triangular teeth, each tooth with denticulate margins and longitudinal median ridge. Chela with 6 lamelliform teeth; outer surface of manus with scattered small granules, becoming very dense on surfaces adjacent to ventral margin; ventral margin lined with row of granules, separated from each other by narrow space; upper half of palm with several large but relatively low mammilliform tubercles. Ambulatory legs slender, surfaces smooth; first leg longest; merus, carpus and propodus laterally flattened; dactylus styliform, gently curved. Male thoracic sternites 4–6 relatively low, broad. Male abdominal somite 6 subrectangular, wider than long; median tubercles on abdominal somites 2–4 relatively low, flat; telson acutely triangular, distal part converging suddenly to form sharp tapering tip. G1 C-shaped; tip truncated.

Description of male. Carapace rounded to subovate, distinctly wider than long. Dorsal surface strongly convex, anterior two-thirds covered with large, round submammillate tubercles, resembling pustules; posterior third relatively smooth; with transverse row of low tubercles just before posterior margin of clypeiform process, forming shallow groove which is covered with numerous small granules. Gastric region swollen, with median part highest point of carapace; longitudinal gastro-cardiac grooves deep, spaced relatively close to each other, especially along posterior part. Frontal margin bifurcated with 2 low, rounded knobs, separated by wide V-shaped sulcus. Supraorbital margin granular, with 2 narrow longitudinal fissures. Eyes folded obliquely, external orbital tooth low, rounded. Pterygostomian lobe at end of posterior margin of epistome with relatively narrow inner oblique longitudinal groove. Basal antennal segment subtriangular, smooth with median ridge; distal margin notched. Longitudinal epistomial septum appears truncated anteriorly, completely covered by closed third maxillipeds. Anterolateral margin arcuate, with 11 or 12 blunt, rounded unevenly sized tubercles; last 6 or 7 tubercles stronger. Posterolateral margin of clypeiform expansion well developed, with 7 (rarely 8) triangular teeth, each tooth with denticulate margins, longitudinal median ridge (sometimes poorly defined or indiscernible in last 2 or 3 teeth); first anterior, last teeth smallest, fourth tooth usually largest; second to fourth teeth progressively larger, fourth to seventh teeth progressively smaller; first to fifth or sixth tooth directed obliquely outwards; seventh (occasionally sixth) tooth directed posteriorly, flanking first abdominal somite.

Chelipeds asymmetrical, right larger. Chela high, dorsal margin with prominent crest, with 6 lamelliform teeth, first low, broadly triangular, blunt, next 5 acutely triangular, sharp; last tooth sometimes with low accessory tooth; outer surface of manus with scattered small granules, becoming very dense on surfaces adjacent to ventral margin; ventral margin lined with row of granules, separated from each other by narrow space; with prominent triangular tooth on proximal edge of ventral margin; upper half of palm with several large but relatively low mammilliform tubercles. Dactylus of major chela with distinct basal curved cutting tooth, rest of margin unarmed; pollex with 3 molariform teeth, first tooth largest, subsequent teeth small. Dactylus of minor chela slender, curved, proximal twothirds granulated, cutting margin lined with denticles; pollex relatively stouter, surface granulated, cutting margin lined with numerous denticles. Ambulatory legs slender, surfaces smooth; first leg longest; merus, carpus, propodus laterally flattened; dactylus styliform, gently curved.

Thoracic sternum narrow; sternites 1, 2 completely fused; separated from sternite 3 by convex shallow groove; sternites 3, 4 fused but median sutures still visible, medially interrupted with short longitudinal depression. Male thoracic sternites 4–6 relatively low, broad ( Fig. 8 C). Sterno-abdominal cavity almost reaching to thoracic suture 3/ 4.

Abdomen relatively narrow; somite 1 longitudinally narrow with lateral parts expanded, surface granulated; somite 2 with lateral parts expanded to form auriculiform process, surface granulated, with median tubercle; somites 3‒5 fused but median sutures just visible or almost absent, more prominent laterally, with distinct clefts separating them; somite 3 sub-rectangular, outer margin appears crested, granulated, scalloped; somite 4 trapezoidal, lateral margins almost straight to slightly concave, granulated; somite 5 rectangular, lateral margins concave, distal edge granulated; somite 6 subrectangular, wider than long, lateral margins concave; median tubercles on somites 2 ‒4 relatively low, flat ( Fig. 8 C); telson acutely triangular, distal part converging suddenly to form sharp tapering tip; lateral margins sinuous.

G1 relatively stout, C-shaped; tip truncated, distal surface lined with numerous minute spinules. G2 subequal in length to G1, slender, curved, distal tip rounded.

Remarks. Calappa exanthematosa Alcock & Anderson, 1894 , is similar to C. japonica Ortmann, 1892 , and it is not surprising that the two taxa have been regarded as synonyms for so long. A comparison of the material at hand, however, shows differences in the live colour, carapace (general form, shape of the lateral teeth, position of the longitudinal gastro-cardiac grooves, structures of the posterior region), pterygostomian lobe, ventral margin of the chela, male abdominal somite 6, male telson and G1, which argue against this synonymy. The major differences are summarised in Table 1 .

Although the dorsal carapace surface of both C. japonica and C. exanthematosa have yellow tubercles surrounded by maroon; the pattern of the spots on the posterior half of the carapace is somewhat different. In adult C. japonica , the maroon spots are often connected with each other to varying degrees, appearing semi-reticulated ( Fig. 3 A, B; see also Miyake 1983: pl. 7 fig. 5). This is true for all the adult specimens examined. Sakai (1976: pl. 40 fig. 2) illustrated a Japan specimen in which the maroon spots are separate but his figure appears to be schematic and it may also be of a juvenile specimen in which the dots are less pronounced. In C. exanthematosa , the maroon spots on the posterior half of the carapace are always separate, demarcated by cream area around each and without any trace of a reticulate pattern ( Fig. 2 ).

Calappa exanthematosa is also close to C. africana , both being from the Indian Ocean, but most of the characters that have been discussed at length by Lai & Ng (2006) to separate C. africana from C. japonica also apply to C. exanthematosa . One of the salient differences is colour. Calappa africana was described as follows: “… the dorsal surface of the carapace is beige to light brown in colour, speckled with salmon pink to light red mottles” ( Lai & Ng 2006: 44) ( Fig. 3 C). The colour of C. exanthematosa was described as “…in the anterior half is covered with numerous large smooth isolated mammillary tubercles, which by their coloration (red base and shining yellow apex) exactly resemble ripe small-pox pustules. In the posterior half of the carapace the place of these well-defined "pustules" is taken by equally well-defined round or oval slightly-raised red patches, which exactly resemble the "papules" of the earlier stage of small-pox.” ( Alcock & Anderson 1894: 178) ( Figs. 1 A, 2, 4). This is a similar to the adult colour pattern of C. japonica (see Fig. 3 A, B), although there are differences in patterning (see above, Table 1 ).

The prominent longitudinal gastro-cardiac grooves on the carapace are deep in both C. japonica and C. exanthematosa , but posteriorly, they are positioned relatively further apart in C. japonica ( Fig. 5 A versus Fig. 5 B). The grooves in C. africana on the other hand, are relatively shallower and become barely discernible along the posterior part ( Fig. 5 C). The rounded tubercles that line the frontal and orbital margins in C. japonica and C. exanthematosa ( Fig. 6 A, B) are relatively low but are pronounced and relatively larger in C. africana ( Fig. 6 C).

The structure of the pterygostomian lobe has not been previously used as a character. This structure is situated at the lateral edge of the posterior margin of the epistome and is part of the anterolateral margin of the buccal cavity. In Calappa species, it takes the form of an oblique lobe with two obliquely parallel grooves, the inner one being relatively broader. The inner groove of this lobe is relatively broader in C. japonica ( Fig. 6 A; C. africana , Fig. 6 C) when compared to C. exanthematosa ( Fig. 6 B). The characters used here (except for the G1) are valid even for small specimens.

Although both C. exanthematosa and C. africana occur only in the Indian Ocean, the latter species is thus far only known from South Africa and Kenya, and seems to be endemic to that region of Africa. Calappa exanthematosa appears to have a broader range, from the northwestern Indian Ocean across to India and Western Australia. Although the male abdomen of C. exanthematosa ( Fig. 8 C, D) more closely resembles that of C. africana (see Lai & Ng 2006: 4D), particularly in the shape of somite 6 and telson, the telson of C. exanthematosa is proportionately longer. The G1 structures also differ; in C. exanthematosa , the G1 is distinctly C-shaped with the tip less truncate ( Fig. 9 D–F) compared to C. africana (see Lai & Ng 2006: 4A, B).

The specimens from NHM and ZMUC were both labeled as syntypes of C. exanthematosa ( Galil 1997: 301; Lai & Ng 2006) and Lai & Ng (2006: 46) designated the NHM specimen as the lectotype ( Fig. 1 C). The ZMUC specimen is not a syntype as it was clearly collected later after the type series, with none of the station data agreeing. Alcock & Anderson (1894: 178) commented about the material they had on hand: “Two males — the largest measuring 116 millim. across the carapace proper, and 126 millim. across the arch formed by the adducted chelipeds — from stations 159 and 170; 112 and 107 fms. respectively; and three small females from Station 169; 91 fms.”. The present lectotype NHM male collected from 107 fms depth is clearly the smaller male referred to by Alcock & Anderson (1894).

The records of “ C. japonica ” by Galil (1997: 300) are composite as she had specimens of three species. Galil’s (1997: 301) record from Kenya has been referred to C. africana Lai & Ng, 2006 . The remaining material belongs to C. japonica and C. exanthematosa ; and all the figures she provided are of the latter species as they are based on the NHM lectotype specimen of C. exanthematosa .

Jones’ (1989) record of C. japonica from Western Australia should also be referred to C. exanthematosa . The male telson figured ( Jones 1989: fig. 1E) agrees very well with what is here defined as that species; and the G1 also more closely resembles that of C. exanthematosa , especially in the more curved shape and more truncate tip ( Jones 1989: fig. 2A). Records of this species from Australia by Jones (1989) and Jones & Morgan (2002) are all from the western part, so they should also be referred to C. exanthematosa for the time being. The first record of C. japonica from Australia by Campbell (1971) is probably valid as the material was from Queensland in the Indo-West Pacific.

In treating material from the Red Sea, Spiridonov & Apel (2007: 2855) commented, “… the carapace of the juvenile specimens from the Red Sea have a subcircular rather than an elliptical shape and, in general, more distinct tubercles and stronger granulation than those from Japan ”. However, these differences were attributed to variation. The study of more material has shown that there are sufficient differences that warrant recognising the material from the Red Sea, Gulf of Aden and Gulf of Oman material as a separate species from C. japonica ( Table 1 ). Spiridonov & Apel (2007) agreed with Grindley’s (1961: 132) record from Natal as C. japonica , but this should be referred to C. africana instead.

Figures

FIGURE 1. Calappa exanthematosa Alcock & Anderson, 1894. A, B (syntype, after Alcock & Anderson 1895: pl. 15 figs. 1, 1 a); C, lectotype male (80.5 × 58.4 mm) (NHM 1896.9.8.8).

FIGURE 2. Colour in life. Calappa exanthematosa Alcock & Anderson, 1894. A, B, sex not known, not preserved, Sri Lanka (courtesy of R. Pethiyagoda); C, male (136.0 × 94.0 mm) (ZRC 2011.0779), Jask, Gulf of Oman; D, female (97.0 × 68.0 mm) (ZRC 2011.0780), Beris, Gulf of Oman.

FIGURE 3. Colour in life. A, Calappa japonica Ortmann, 1892, female (ZRC 2009.0436), Vanuatu (photograph T. - Y. Chan); B, C. japonica Ortmann, 1892, male (49.7 × 40.0 mm) (ZRC 2001.0346), Philippines; C, C. africana Lai & Ng, 2006, paratype female (105.8 × 80.5 mm) (ZRC 2006.0109), South Africa (colour shortly after preservation).

FIGURE 4. Calappa exanthematosa Alcock & Anderson, 1894. Female (97.0 × 68.0 mm) (ZRC 2011.0780), Beris, Gulf of Oman. A, dorsal view; B, frontal view; C, outer view of right chela; D, outer view of left chela.

FIGURE 5. Posterior view of carapace. A, Calappa japonica Ortmann, 1892, male (140.7 × 98.8 mm) (ZRC 2001.0002), Taiwan; B, C. exanthematosa Alcock & Anderson, 1894, male (136.0 × 94.0 mm) (ZRC 2011.0779), Jask, Gulf of Oman; C, C. africana Lai & Ng, 2006, paratype female (80.5 × 105.8 mm) (ZRC 2006.0109), South Africa.

FIGURE 6. Frontal view of carapace showing pterygostomian lobe (arrow). A, Calappa japonica Ortmann, 1892, male (140.7 × 98.8 mm) (ZRC 2001.2), Taiwan; B, C. exanthematosa Alcock & Anderson, 1894, male (136.0 × 94.0 mm) (ZRC 2011.0779), Jask, Gulf of Oman; C, C. africana Lai & Ng, 2006, paratype female (80.5 × 105.8 mm) (ZRC 2006.0109), South Africa.

FIGURE 8. Male abdominal somite 6 and telson. A, Calappa japonica Ortmann, 1892, male (49.7 × 40.0 mm) (ZRC 2001.0346), Philippines; B, C. japonica Ortmann, 1892, male (140.7 × 98.8 mm) (ZRC 2001.0002), Taiwan; C, C. exanthematosa Alcock & Anderson, 1894, male (46.4 × 35.3 mm) (ZMUC), Bay of Bengal; C, C. exanthematosa Alcock & Anderson, 1894, male (136.0 × 94.0 mm) (ZRC 2011.0779), Jask, Gulf of Oman.

FIGURE 9. A – C, Calappa japonica Ortmann, 1892, male (140.7 × 98.8 mm) (ZRC 2001.2), Taiwan; D – F, Calappa exanthematosa Alcock & Anderson, 1894, male (136.0 × 94.0 mm) (ZRC 2011.0779), Jask, Gulf of Oman. A, D, dorsal view of right G 1; B, E, ventral view of right G 1; C, F, distal part of right G 1 (ventral view). Scales: A, B, D, E = 5.0 mm; C, F = 1.0 mm.

Tables

TABLE 1. Differences between Calappa japonica and C. exanthematosa.

	Calappa japonica	Calappa exanthematos a
Colour in life	Maroon spots on posterior half of carapace connected with each other to varying degrees, forming reticulated appearance (Fig. 3A, B)	Maroon spots on posterior half of carapace independent, demarcated by cream area around each, not connected, area appears distinctly spotted (Fig. 2)
Carapace	Dorsal surface appears swollen (Figs. 3A, B, 5A)	Dorsal surface relatively more swollen (Figs. 1, 2, 4, 5B)
Lateral teeth of carapace	Relatively more elongate in adults, with tip gently curved upwards (Figs. 3A, B, 5A)	Evenly triangular in adults, with tip level with rest of tooth (Figs. 1, 2, 4, 5B)
Longitudinal gastro-cardiac grooves	Spaced relatively wide apart (Fig. 5A)	Spaced relatively close (Fig. 5B)
Posterior regions of cara- pace	May have scattered tubercles and granules but not forming any distinct transverse groove of any sort (Fig. 5A)	Distinct uneven row of tubercles present behind posterior margin of carapace, forming shallow but distinct transverse groove which is lined by small granules (Fig. 5B)
Pterygostomian lobe	Inner oblique longitudinal groove relatively broad (Fig. 6A)	Inner oblique longitudinal groove relatively nar- row (Fig. 6B)
Chelae	Ventral surface of manus with scattered rounded granules and tubercles; ventral mar- gin lined with numerous closely packed rounded granules (Fig. 7A)	Ventral surface of manus with relatively more prominent scattered rounded granules and tubercles; ventral margin lined with numerous granules which are spaced further apart (Fig. 7B)
Male thoracic sternites 4–6	Relatively higher, narrower (Fig. 8A)	Relatively lower, broader (Fig. 8C)
Median tubercles on abdominal somites 2–4	Relatively high, distinct (Fig. 8A)	Relatively low, flat (Fig. 8C)
Male abdominal somite 6	Squarish (Fig. 8A, B)	Rectangular, broader than long (Fig. 8C, D)
Male telson	Evenly triangular (Fig. 8A, B)	Relatively more elongate with distal third taper- ing sharply (Fig. 8C, D)
G1	Gently curved, weakly C-shaped; tip taper- ing (Fig. 9A–C)	More strongly curved, distinctly C-shaped; tip subtruncate to gently rounded (Fig. 9D–F)