Ilyograpsus nodulosus Sakai, 1983

Komai, Tomoyuki & Wada, Keiji, 2008, A Revision Of The Estuarine Crab Genus Ilyograpsus Barnard, 1955 (Crustacea: Decapoda: Brachyura: Macrophthalmidae), With Descriptions Of A New Genus And One New Species, Raffles Bulletin of Zoology 56 (2), pp. 357-384 : 365-370

Ilyograpsus nodulosus Sakai, 1983

( Figs. 6–8 )

Iliograpsus [sic] nodulosus Sakai, 1983: 19 , 42, Pl. 4, Fig. E.

Ilyograpsus nodulosus Kishino et al., 2001a: 16 , Pl. 1(4); 2001b: 126; Nakasone & Irei, 2003: 273; Sawada et al., 2005: 857 (in part), Figs. 2A, D , 3B ; Naruse, 2005: 221; Naruse & Kishino, 2006: 73, Figs. 2b , 5 .

Ilyograpsus paludicola Yamaguchi et al., 1976: 41, Fig. 2 (8); Fukuda, 1978: 15; Yamaguchi et al., 1987: 31, Pl. 14, Fig. 8 ; Nakasone & Irei, 2003: 273. Not Ilyograpsus paludicola ( Rathbun, 1909) .

Not Ilyograpsus nodulosus Sawada et al., 2005 , Figs. 4C , 5A, C, E . = Ilyograpsus paludicola ( Rathbun, 1909) .

Name bearing type. – Holotype: sex not indicated (cl 3.9, cw 4.2 mm), mangroves of Kuira River, Iriomote Island, Yaeyama Islands, coll. H. Yoshikawa. Presumably no longer extant (Naruse & Kishino, 2006; pers. obs.). See Remarks.

Material examined. – Japan. 1 ovigerous female (cl 5.7 mm), CBM- ZC 9418 , Waka River estuary, 14 Jul.1999, coll. A. Nomoto ; 1 male (cl 4.0 mm), CBM-ZC 9419 , Kinokawa River estuary, Wakayama, Wakayama Prefecture, 15 Jul.1999, coll. A. Nomoto ; 1 male (cl 4.4 mm), CBM-ZC 9420 , Funao, Kainan , Wakayama Prefecture, 13 Jul.1999, coll. A. Nomoto ; 5 males (cl 3.3–4.5 mm), 1 female (cl 4.6 mm), 3 ovigerous females (cl 5.7–7.5 mm), CBM-ZC 9304 , Arita River estuary at Koemi, Arita , Wakayama Prefecture, 5 May 2004, mud, dip net, coll. A. Nomoto ; 1 ovigerous female (cl 5.6 mm), CBM-ZC 9421 , Hidaka River estuary, Shioya, Gobo , Wakayama Prefecture, 30 Jul.2000, coll. A. Nomoto ; 2 males (cl 3.1, 3.6 mm), CBM-ZC 9422 ; Fukuro, Shirahama , Wakayama Prefecture, 19 Aug.2001, coll. T. Watanabe ; 1 female (cl 3.8 mm), CBM-ZC 9305 , Mukai-higashi-cho, Onomichi, Hiroshima Prefecture, Seto Inland Sea , tidal flat, mud, 8 Aug.2002, dip net, coll. A. Nomoto ; 3 male (cl 2.8–3.6 mm), 1 female (cl 3.9 mm), CBM-ZC 9306 , Mishou Bay, Minami-Uwa District , Ehime Prefecture, subtidal, 19 Apr.2004, coll .

I. rhizophorae I. vannini * I. nodulosus I. paludicola I. daviei , new species

Carapace Width/length (/) 1.21–1.33 (n=4, 1.27)/ 1.15 (only female) 1.06–1.14 (n=19, 1.10)/ 1.08–1.17 (n=10, 1.13)/ 1.12–1.19 (n=6, 1.15)/

1.21–1.32 (n=6, 1.26) 1.05–1.19 (n=25, 1.12) 1.09–1.19 (n=12, 1.13) 1.15–1.21 (n=11, 1.19)

Regions poorly defined poorly defined strongly defined well defined relatively weakly defined

Postfrontal ridges less distinct less distinct distinct, often crested distinct, often crested distinct

Epigastric ridges absent absent present present present or rudimentary

Second anterolateral tooth moderately large small moderately large moderately large moderately large

Third anterolateral tooth well exceeding beyond exceeding nearly as far well exceeding beyond well exceeding beyond well exceeding beyond in females second tooth as second tooth second tooth second tooth second tooth

Upper orbital margin slightly oblique oblique transverse transverse transverse

Lower orbital margin with distinct lobules/ unknown without distinct lobules/ with distinct lobules/ with distinct lobules/ (/) with row of 13–18 small, with row of 20–23 minute with row of 13–18 small, with row of 13–18 small,

unequal granules granules unequal granules unequal granules

Merus of cheliped with subdistal spine with subdistal spine unarmed or with minute with subdistal spine with subdistal spine tubercles subdistally

Fourth pereopod Merus length/width (/) 3.48–3.84 (n=2, 3.66)/ unavailable 3.40–4.64 (n=10, 4.14)/ 3.21–4.12 (n=8, 3.69)/ 2.47–3.02 (n=5, 2.88)/

2.52 (n=1) 2.72–4.00 (n=13, 3.52) 3.17–3.79 (n=7, 3.50) 2.24–2.77 (n=10, 2.56)

Propodus length/width 4.38–4.47 (n=2, 4.43)/ unavailable 4.07–5.80 (n=11, 5.00)/ 4.16–5.90 (n=8, 5.14)/ 3.27–3.58 (n=5, 3.44)/ (/) 3.56 (n=1) 4.08–5.38 (n=12, 4.66) 4.69–6.00 (n=6, 5.08) 3.18–3.85 (n=10, 3.41)

Dactylus/propodus (/) 0.74–0.80 (n=1, 0.77)/ unavailable 0.87–1.02 (n=11, 0.95)/ 0.68–0.80 (n=8, 0.77)/ 0.64–0.87 (n=5, 0.80)/

0.77 (n=1) 0.90–1.04 (n=11, 0.97) 0.71–0.89 (n=7, 0.82) 0.72–0.86 (n=10, 0.80)

Fifth pereopod Propodus length/width 2.81 (n=1)/3.59 (n=1) unavailable 2.55–3.33 (n=11, 3.03)/ 3.03–4.27 (n=9, 3.61)/ 2.00–2.87 (n=5, 2.43)/ (/) 2.63–3.36 (n=11, 2.93) 2.83–3.27 (n=7, 3.27) 2.05–2.45 (n=9, 2.09)

Terminal process of G1 moderately long, curved unknown short, subtruncate moderately long, slightly moderately long, slightly laterally curved dorsally curved dorsally

K. Wada ; 1 female (cl 3.7 mm), 1 ovigerous female (cl 5.1 mm), CBM-ZC, similar locality, 20 Apr.2004, coll. K. Wada ; 1 ovigerous female (cl 6.5 mm), SINH-CR 1151 , Kaminokae River , Nakatosacho, 16 Jun.2004, coll. A. Yamamoto ; 1 ovigerous female (cl 5.6 mm), SINH-CR 1152 , same data as SINH-CR 1151 ; 1 ovigerous female (cl 6.0 mm), SINH-CR 1257 , Nishi-nada , Urado Bay , Kochi, Kochi Prefecture, 21 Jun.2004, coll. A. Yamamoto ; 1 male (cl 4.1 mm), SINH-CR 1258 , same data as SINH-CR 1257 ; 1 male (cl 4.2 mm), SINH-CR 1259 , same data as SINH-CR 1257 ; 1 ovigerous female (cl 5.7 mm), SINH-CR 1274 , Nishi-nada , Urado Bay, 22 Jun.2004, coll. A. Yamamoto ; 4 ovigerous females (cl 4.7–6.9 mm), SINH-CR 1275 , same data as SINH-CR 1274 ; 2 ovigerous females (cl 5.3, 6.1 mm), SINH-CR 1350 , Suzaki , Kochi Prefecture, 9 Apr.2004, coll. A. Yamamoto ; 1 ovigerous female (cl 6.0 mm), SINH-CR 1371 , Suzaki , 4 Jul.2004, coll. A. Yamamoto ; 1 male (cl 4.0 mm), SINH-CR 1372 , same data as SINH-CR 1371 ; 17 males (cl 5.6 mm), 30 females (cl 4.8–6.6 mm), SINH-CR 1373 , same data as SINH-CR 1371 ; 1 male (cl 3.2 mm), 4 ovigerous females (cl 4.5–5.5 mm), SINH-CR 1418 , Fukaura , Urado Bay, 7 Jun.2004, coll. A. Yamamoto ; 1 ovigerous female (cl 7.8 mm), SINH 1474 , Nada , Urado Bay, 3 Aug.2004, coll. A. Yamamoto ; 2 ovigerous females (cl 5.6, 5.7 mm), SINH-CR 1493 , Suzaki , 5 Aug.2004, coll. A. Yamamoto ; 1 male (cl 3.1 mm), 2 ovigerous females (cl 4.9, 6.3 mm), SINH-CR 1522 , Sakura-gawa rivermouth estuary, Suzaki, Kochi Prefecture, 20 Apr.2004, coll. A. Yamamoto ; 2 males (cl 3.8, 4.1 mm), CBM-ZC 9386 , Shimanto River estuary at Shimoda , Nakamura, Kochi Prefecture, tidal flat, mud, dip net, 4 Jun.2004, coll. A. Nomoto ; 3 males (cl 3.2–4.1 mm), 3 females (cl 3.4–5.4 mm), CBM-ZC 9387 , Tomouchi River estuary, Nobeoka, Miyazaki Prefecture, 27 Apr.2006, beach seine, coll. N. Sakai ; 3 males (cl 2.7–4.5 mm), 2 ovigerous females (cl 4.4, 4.9 mm), CBM-ZC 9233 , Yanma , Sumiyo Village, Amami-Oshima Island, 31 Mar.2002, coll. T. Kishino ; 2 ovigerous females (cl 6.4, 6.5 mm), CBM-ZC 9232 , Naikai , Sumiyo Village, Amami-Oshima Island, 2 May.2003, coll. T. Kishino ; 2 ovigerous females (cl 4.8, 4.9 mm), CBM-ZC 8841 , Yanma Port , mudflat, under rock, Sumiyo Village, Amami-Oshima Island, intertidal, 28 Apr.2006, hand, coll. T. Komai ; 1 female (cl 4.3 mm), 1 ovigerous female (cl 4.9 mm), CBM-ZC 9224 , Fukuchi River estuary, Ginoza Village, Okinawa Island, 5 Aug.2001, coll. T. Kishino ; 1 ovigerous female (cl 6.1 mm), RUMF-ZC-242, Tima River estuary, Nago, Okinawa Island, 24 Apr.2005, coll. T. Naruse ; 2 females (cl 4.0, 4.1 mm), ZRC 2005.0114 , Tima River estuary, Nago, Okinawa Island, 13 Feb.2005, coll. T. Naruse ; 2 males (cl 3.5, 3.6 mm), 1 ovigerous female (cl 5.5 mm), CBM-ZC 9235 , Shiira River estuary, Iriomote Island, Yaeyama Islands, 22 Mar.2005, coll. T. Naruse ; 3 males (cl 3.3–3.4 mm), 1 female (cl 4.9 mm), Shirahama , Iriomote Island, sea grass beds on tidal flat, 23 Jun.2005, dip net, coll. T. Komai .

Description of male. – Carapace ( Fig. 7A, B ) suboctogonal, breadth 1.06–1.14 times length (n = 19, mean 1.10); regions clearly defined. Postfrontal ridges distinct, often crested. Epigastric ridges or tubercles present. Cardiac region with paired low elevations; branchial regions with 2 pairs of low elevations on either side of gastro-cardiac region, and with 2 short longitudinal ridges laterally. Lateral margins generally convex, greatest carapace breadth between third anterolateral teeth. Four anterolateral teeth present, first tooth (external orbital tooth) largest, subacute or acute; second tooth extending as far as or slightly exceeding external orbital tooth, rounded or bluntly triangular; third tooth extending clearly exceeding beyond external orbital tooth, varying from blunt to acuminate; fourth tooth small, but clearly delineated, blunt or subacute; sometimes slight notch posterior to fourth tooth. Front prominent, distinctly bilobed, less than hind width, about 0.4 times front-orbital width, wider than orbit. Upper orbital margin slightly sinuous, nearly transverse; lower orbital margin granular, without conspicuous lobules laterally.

Ocular peduncle ( Fig. 7A, B ) overreaching external orbital tooth, length about 2.2–2.3 of corneal width; cornea not dilated.

Cheliped ( Fig. 7E–G ) relatively small. Merus with or without minute subdistal granule on dorsal margin; no distinct subdistal crest on anteroventral margin. Chela about 2.7 times as long as high; cutting edge of fixed finger with row of small blunt teeth in proximal 0.8 and thin chitinous ridge in distal 0.2; dactylus slightly curved, about 1.2–1.3 times longer than palm, cutting edge with row of small rounded teeth in proximal 0.7, remainder bordered by thin chitinous ridge.

Ambulatory legs ( Fig. 6A ) relatively long, slender. Meri each with relatively large subdistal spine. Fourth pereopod (third ambulatory leg) ( Fig. 7H ) with merus 3.40–4.64 times longer than broad (n = 10, mean 4.14), anterior margin faintly sinuous or straight, posterior margins slightly convex; propodus 4.07–5.80 times longer than broad (n = 10, mean 5.00); dactylus 0.87–1.02 times as long as propodus (n = 11, mean 0.95). Fifth pereopod (fourth ambulatory leg) ( Fig. 7I ) with propodus 2.55–3.33 times longer than broad (n = 11, mean 3.03), outer and inner margins fringed with short setae; dactylus longer than propodus.

Sixth pleonal somite ( Fig. 7D ) with slightly convex lateral margins, about 2.6–2.7 times broader than long. Telson rounded terminally; breadth about 1.1–1.2 times length.

First gonopod ( Fig. 7J, K ) relatively stout, very slightly curved; terminal process very short, truncate, partially obscured by stiff setae.

Description of female. – Carapace ( Fig. 8A, B ) breadth about 1.05–1.19 (n = 25, mean 1.12) times length; greatest carapace breadth between third anterolateral teeth. Regions on dorsal surface well defined; elevations on dorsal surface sometimes ornamented by short granular ridges or tubercles; cardiac region divided in 3 lobes (2 anterior and 1 posterior). Second anterolateral tooth exceeding external orbital tooth. Third anterolateral tooth distinctly exceeding second anterolateral tooth. Lower orbital margin ( Fig. 8C ) bordered by row of 20–23 minute granules.

Ocular peduncle ( Fig. 8A ) reaching external orbital tooth.

Cheliped ( Fig. 8E, F ) generally similar to that of I. rhizophorae . Dorsal margin of merus with minute denticle or tubercle subdistally or completely unarmed. Chela about 3.4 times as long as high; ventral margin concave with fixed finger weakly deflexed; cutting edge of fixed finger faintly denticulate in proximal 0.8 and bordered by thin chitinous ridge in distal 0.2; dactylus slightly curved, cutting edge nearly smooth in proximal 0.7, bordered by thin chitinous ridge in distal 0.2.

Ambulatory legs ( Fig. 6B ) relatively longer, more slender compared with congeners. Meri each with relatively large subdistal spine on anterior margin. Fourth pereopod (third ambulatory leg) with merus 2.72–4.00 times longer than broad (n = 13, mean 3.52), anterior margin sinuous; propodus 4.08–5.38 times longer than broad (n = 12, mean 4.66); dactylus 0.90–1.04 times as long as propodus (n = 11, mean 0.97). Fifth pereopod (fourth ambulatory leg) with propodus 2.63–3.36 times longer than broad (n = 11, mean 2.93), outer and inner margins with fringe of short stiff setae; dactylus subequal to or longer than propodus.

Size. – Males cl 2.8–4.5 mm; females cl 3.9–7.8 mm, ovigerous females cl 4.4–7.8 mm.

Colour in life. – Entirely muddy brown; ambulatory legs with faint darker bands.

Distribution. – Known with certainty only from southern Japan, including Seto Inland Sea, Shikoku, Kyushu and Ryukyu Islands southward to Iriomote Island in Yaeyama Islands.

Remarks. – As Naruse & Kishino (2006) noted, the holotype of Ilyograpsus nodulosus has not been located, and it is highly possible that it has been lost after the death of Prof. T. Sakai. However, the present material contains topotypic specimens from the Iriomote Island, and there is no serious problem in establishing the taxonomic identity of the taxon.

The available material suggests that male attains much smaller size than female does in this species.

As noted before, Ilyograpsus nodulosus appears closest to I. paludicola . Shared characters include: the regions of the carapace are relatively well defined, particularly in males; epigastric ridges or tubercles are present on the carapace; the ambulatory legs are relatively long and slender. Ilyograpsus nodulosus is distinguished from I. paludicola by the following characters ( Table 1). The lower orbital margin in females bears 20–23 minute granules in I. nodulosus , rather than 13–18 small, unequal granules in I. paludicola . The merus of the cheliped lacks a distinct subdistal spine on the dorsal margin and a short subdistal crest on the anteroventral margin in I. nodulosus , whereas these structures are well developed in I. paludicola . The ambulatory legs are more slender in I. nodulosus than in I. paludicola , though sexual difference should be concerned. The dactylus of the fourth pereopod is proportionally longer in I. nodulosus than in I. paludicola . The terminal margin of the first gonopod of I. nodulosus is truncate with a poorly developed terminal process. In. I. paludicola , the terminal process of the first gonopod is conspicuous.

We have examined material from various localities in the Indo- West Pacific, but the occurrence of I. nodulosus outside of the Japanese Archipelago was not confirmed. On the other hand, the occurrence of I. paludicola in Japan was not confirmed too. Thus, we consider that previous records of I. paludicola (see Yamaguchi et al., 1976, 1987; Fukuda, 1978; Nakasone & Irei, 2003) were results of misidentifications, and they are all referred to I. nodulosus . Sawada et al. (2005) identified a single ovigerous female from Nouméa, New Caledonia and nine specimens from Brisbane River, Brisbane, Queensland, Australia, with I. nodulosus , but later Naruse & Kishino (2006) questioned the identification. After reexamination, we have confirmed that the specimen from New Caledonia (ovigerous female, OMNH-Ar 1656) actually represents I. paludicola (see Remarks of I. paludicola ). Specimens from Queensland we have examined during this study all represent I. daviei , new species, and thus there is little doubt that the specimens from the Brisbane River used by Sawada et al. (2005) could represent I. daviei , new species.

Figures

Fig. 6. Ilyograpsus nodulosus Sakai, 1983. Entire animals in dorsal view.A, male (cl 4.3 mm), SINH-Cr 1373, Suzaki, Kochi Prefecture, Japan; B, ovigerous female (cl 7.8 mm), SINH-Cr 1474, Nada, Urado Bay, Kochi, Kochi Prefecture, Japan.

Fig. 7. Ilyograpsus nodulosus Sakai, 1983. Male (cl 4.9 mm), SINH-Cr 1373, Suzaki, Kochi Prefecture, Japan.A, carapace, ocular peduncles and antennae, dorsal view; B, cephalothorax and cephalic appendages, frontal view; C, left lower orbital margin and external orbital tooth, ventral view; D, pleon, ventral view; E, merus of right cheliped, outer view; F, chela and carpus of right cheliped, dorsal view; G, right chela, outer view; H, left fourth pereopod, dorsal view; I, left fifth pereopod, dorsal view; J, left first gonopod, ventral view; K, same, dorsal view. Scale bars: A, B, D, E–I = 1 mm; C, J, K = 0.5 mm.

Fig. 8. Ilyograpsus nodulosus Sakai, 1983. Female (cl 7.8 mm), SINH-Cr 1474, Nada, Urado Bay, Kochi, Kochi Prefecture, Japan. A, carapace, ocular peduncles and antennae, dorsal view (setae omitted); B, cephalothorax and cephalic appendages, frontal view; C, left lower orbital margin, ventral view; D, sixth pleonal somite and telson, ventral view (setae omitted); E, merus of left cheliped, outer view; F, carpus and chela of left cheliped, outer view; G, left fourth pereopod, dorsal view; H, left fifth pereopod, dorsal view. Scale bars: A, D = 2 mm; B, E–H = 1 mm; C = 0.5 mm.

Fig. 2. Ilyograpsus rhizophorae Barnard, 1955. Male (cl 6.4 mm), paratype of Ilyograpsus vannini Sawada, Hosogi & Sakai, 2005, RMNH-D 26501, south of Massawa, Gulf of Zula, Ethiopia. Entire animal in dorsal view.

Fig. 3. Ilyograpsus rhizophorae Barnard, 1955. Male (cl 6.5 mm), paratype of Ilyograpsus vannini Sawada, Hosogi & Sakai, 2005, RMNH- D 26501, south of Massawa, Gulf of Zula, Ethiopia: A, carapace, ocular peduncles and antennae, dorsal view (setae omitted); B, left lower orbital margin and external orbital tooth, ventral view; C, anterior part of thoracic sternum, ventral view; D, pleon, ventral view; E, left cheliped, dorsal view; F, same, merus, outer view; G, same, chela, outer view; H, left fourth pereopod, dorsal view; I, left fifth pereopod, dorsal view; J, left first gonopod, ventral view; K, same, ventrolateral view; L, same, distal part, dorsal view. Scales: A = 2 mm; B–I = 1 mm; J–L = 0.5 mm.

Fig. 5. Ilyograpsus rhizophorae Barnard, 1955. A–E, I, J, ovigerous female (cl 7.2 mm), MNHN-B 12842, Tuléar, Madagascar; F, H, ovigerous female (cl 5.3 mm), MNHN-B 12843, same locality; G, female (cl 7.4 mm), paratype of Ilyograpsus vannini Sawada, Hosogi & Sakai, 2005, RMNH-D 26501, south of Massawa, Gulf of Zula, Ethiopia. A, carapace, ocular peduncles and antennae, dorsal view; B, anterior part of cephalothorax, including left ocular peduncles and antennae, frontal view; C, left lower orbital margin, ventral view; D, pleon, ventral view; E, left third maxilliped, ventral view; F, left cheliped, dorsal view; G, same, merus, outer view; H, same, chela, outer view; I, right fourth pereopod, dorsal view; J, right fifth pereopod, dorsal view. Scale bars: A, D, F = 2 mm; B, C, E, G, I, J = 1 mm; H = 0.5 mm.

Fig. 4. Ilyograpsus rhizophorae Barnard, 1955. A, male (cl 5.0 mm), paratype of Ilyograpsus vannini Sawada, Hosogi & Sakai, 2005, RMNH-D 26501, south of Massawa, Gulf of Zula, Ethiopia; B–E, male (cl 3.8 mm), MNHN-B 12846, Nozy Bé, Madagascar. A, left part of carapace, left ocular peduncle and antenna, dorsal view; B, left cheliped, dorsal view; C, same, chela, outer view; D, right first gonopod, dorsal view; E, same, ventrolateral view. Scale bars: A, B, D = 1 mm; C, E = 0.5 mm.