Portunus (Portunus) reticulatus (Herbst, 1799)

Lai, Joelle C. Y., Ng, Peter K. L. & Davie, Peter J. F., 2010, A Revision Of The Portunus Pelagicus (Linnaeus, 1758) Species Complex (Crustacea: Brachyura: Portunidae), With The Recognition Of Four Species, Raffles Bulletin of Zoology 58 (2), pp. 199-237 : 218-219

publication ID	https://doi.org/ 10.5281/zenodo.5342701
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scientific name	Portunus (Portunus) reticulatus (Herbst, 1799)
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Portunus (Portunus) reticulatus (Herbst, 1799) View in CoL

( Figs. 6C View Fig , 7C View Fig , 15 View Fig , 16 View Fig , 20C View Fig , 21C View Fig , 22C View Fig , 23C, 23G View Fig , 24C View Fig )

Cancer reticulatus Herbst, 1799: 65 , Pl. 50.

Portunus pelagicus View in CoL – Sakai, 1999: 29, Pl. 15C.

Portunus trituberculatus View in CoL – Stephenson & Rees, 1967a: 17 (material from the Bay of Bengal and India) [not Neptunus trituberculatus Miers, 1876 View in CoL , fide Stephenson 1976: 18].

Neptunus (Neptunus) pelagicus View in CoL – Alcock, 1899: 34; Chopra, 1935: 476, 477, Fig. 3 View Fig ; Chhapgar, 1957: 418, Pl. 6a-c, colour Pl. A6.

Neptunus pelagicus View in CoL – De Man, 1888: 328; Henderson, 1893: 367.

Portunus pelagicus View in CoL – Fabricius, 1798: 367; Stephenson, 1972a: 15 key; Stephenson, 1972b: 137 (part); Stephenson, 1976: 18; Sethuramalingam & Ajmal Khan, 1991: 9 (key), 27, Pl. 18d; Fernando & Fernando, 2002: 62; Vongpanich, 2006: 77.

Portunus (Portunus) reticulatus View in CoL – Ng et al., 2008: 152.

Type locality. – “Das Vaterland ist Ostindien” [somewhere within the region stretching from the east coast of India to the Indo- Malayan Archipelago] .

Material examined. – Lectotype of Cancer reticulatus Herbst, 1799 , female (167.0 × 70.0 mm) ( ZMB Herbst 0312) (photographs examined). Others. – INDIA: 14 males (largest 132.2 × 59.8 mm), 3 females (larger 135.0 × 59.5 mm) ( ZRC 2007.223 View Materials ), Marina Beach Market, Chennai , coll. Z. Jaafar, 23 Nov.2004; 1 male (111.9 × 63.7 mm) ( ZRC 2007.231 View Materials ), Midnapure, Cantai, Danthadhpatrobar, West Bengal, coll. Z. Jaafar; 1 male ( ZRC 2001.894 View Materials ), Porto Novo market, Tamil Nadu, coll. A.S. Fernando, 10 Mar.2001; 2 males (larger 85.6 × 37.6 mm), 1 female (75.7 × 34.3 mm) ( ZRC 2007.209 View Materials ), Porto Novo market, Tamil Nadu, coll. N. K. Ng, Mar.2001; 5 males (largest 38.1 × 17.4 mm) ( NHM 1892.715.330), Pamban, Rameswaran, coll. J. R. Henderson. SRI LANKA: 5 males (largest 141.4 × 62.3 mm) ( ZRC 2007.222 View Materials ), Colombo Market , coll. M. Bahir, 16 Jun 2003; 1 male (132.8 × 58.5 mm) ( NHM 1974.50 ), coll. Osman Hill; 1 female (49.9 × 20.4 mm) ( NHM 60 : 15), Ceylon (?), coll. Schlagintwect, Pres. Sec. India. Board. THAILAND: 8 males (largest 163.4 × 77.23mm), 2 females (larger 134.9 × 61.4mm) ( ZRC 2009.1005 View Materials ), Phuket Pichai fish port, coll. J. C. Y. Lai, 13 Oct.2008; 1 male (116.9 × 53.7mm) ( ZRC 2002.295 View Materials ) Phuket Pichai fish port, coll. J. C. Y. Lai, 2–3 Sep.2001; 1 male (126.6 × 56.0 mm), 1 female (107.0 × 50.1 mm), Phuket Pichai fish port, coll. J. C. Y. Lai, 22–25 Aug.2002; 2 males (larger 65.6 × 29.9 mm) ( ZRC 2000.1058 View Materials ), Phuket, Ao Tang Khen, NE Cape Panwa, coll. H. H. Tan, 19 Jun.2000.

Diagnosis. – Carapace width 2.2–2.3 times wider than long, median frontal teeth spinous, small but conspicuous, similar to P. pelagicus . Adults with regions relatively poorly indicated, branchial regions not markedly swollen. Cheliped merus relatively short, 3.5–3.9 times longer than wide (median 3.6); anterior margin usually with 3 spines; normally without enlarged spine proximally near joint; cheliped manus/dactylus ratio = average 2.30 ± 0.048 (differs significantly from P. pelagicus (P = 0.03, ANOVA)). Ambulatory legs relatively less slender than P. pelagicus ; merus of 4 th pereiopod 3.5 to 3.9 (median 3.7) times longer than wide ( Fig. 21C View Fig ). Natatorial paddle oval but less elongate, more rounded distally than P. pelagicus or P. segnis ( Fig. 21C View Fig ). Sixth male abdominal somite relatively elongate, tapering ( Fig. 22C View Fig ). Base of G1 with small but conspicuous rounded basal spur ( Fig. 20C View Fig ). In males, patterns on carapace may be variable, from dense spots merging into broad reticulating network of bands or few spots and thin reticulations, females similar to males ( Figs. 6C View Fig , 7C View Fig , 16 View Fig ). The maximum size of P. reticulatus (present study) is the lectotype fenale, 167.0 × 70.0 mm (ZMB Herbst 0312).

Live colour ( Figs. 6C View Fig , 7C View Fig , 16 View Fig ). – Males with greenish blue carapace. Patterns of carapace variable, large pale green spots that rarely merge into broad net like bands, to sparsely spotted, with thick reticulations. Females with green brown carapace, surface of carapace marked with numerous dense spots and blotches, without black marking on posterobranchial region. Tips of chelipeds marked bright red.

Remarks. – Herbst described two species of swimming crabs that were subsequently synonymised with Portunus pelagicus by Alcock (1899): Cancer cedonulli Herbst, 1794 , and Cancer reticulatus Herbst, 1799 . Like C. cedonulli , C. reticulatus was described from “Das Vaterland ift Ostindien” (East Indies), an area considered to extend from the east coast of India to the Indo-Malaysian region. Herbst (1799) described C. reticulatus from a female, and it closely matches females we have collected from India (see Figs. 7C View Fig , 15 View Fig ). On the other hand, C. cedonulli appears to be based on a male (Herbst 1794: Pl. XXXIX), and agrees well with male P. pelagicus specimens we have examined from eastern Indonesia. Our earlier neotype designation for C. cedonulli has effectively fixed its identity as an objective junior synonym of P. pelagicus . Nevertheless, as both Herbst’s species were described based on different sexes, and were originally separated largely on colour differences, some comment on sexual dimorphism in colour within this species-complex is needed.

Herbst’s male C. cedonulli (Herbst 1794: tab. XXXIX) was described as follows: “grün mit vielen grossen und kleinen gelben flecken, die ein e dunkelgrune Einfassung habe … unten violett, oben grün, mit gelben Flecken ... Handwurzeln gruen, purpur und gelb gefleckt”. Five years later, Herbst (1799) noted that his new C. reticulatus was very similar to C. cedonulli except that markings on the carapace of C. reticulatus were netlike and purple red (“die netzformigen Züge find purpurroth”), while C. cedonulli possesses a green carapace with many large and small yellow spots, and dark green edge with the underside of merus violet, upper side green with yellow spots, claws green, purple with yellow spots.

Alphonse Milne-Edwards (1861: 321) simply stated that C. cedonulli was blue with yellow spots, while C. reticulatus was red with yellow spots. It must be considered that as species in this group are sexually dimorphic in colouration, carapace ratios, and cheliped merus and manus dimensions, it is possible that first Herbst and then A. Milne-Edwards subsequently, may have incorrectly concluded that males and females represented two different species. However, differences in colour patterning between the two species are real despite sexual differences, and Herbst’s original illustration of P. cedonulli , does show the broad white bands, and spotting size diagnostic of P. pelagicus , as well as matching it in cheliped merus dimensions.

A type specimen of Cancer reticulatus (ZMB Herbst 0312) ( Fig. 15 View Fig ) is extant and part of the Herbst Collection in the Berlin Zoological Museum ( Sakai, 1999). An additional label with this specimen also identifies it as “ Portunus armatus ”, a related species described by A. Milne-Edwards 60 years later in 1861 (see discussion for P. armatus ). However, O. Coleman (Curator of Crustacea at ZMB) does not recognise the penmanship or initials of the label writer; nor was its presence reported by Sakai in his Herbst catalogue (1999). While this label casts some slight doubt over the type status of this specimen, nevertheless its striking similarity to the figure in Herbst (1799: Pl. L), and its presence within the Herbst Collection in the ZMB (which has never been moved or mixed; O. Coleman, pers. comm.), indicates that this specimen can reasonably be regarded as part of the type material of C. reticulatus . As no holotype was originally selected by Herbst (1799), we therefore designate this specimen as the lectotype in accordance with Article 74b of the ICZN.

Habitat. – Found in shallow sandy lagoons; commonly caught with gill nets or trawls ( Ameer Hamsa, 1978).

Distribution. – Portunus reticulatus (Herbst, 1799) appears to be restricted to the Bay of Bengal, and is so far only known from the southeastern coast of the Indian subcontinent, waters off Sri Lanka, and from the Andaman coast of southern Thailand (present study). There appears to be evidence of introgression or incomplete lineage sorting within this species with P. pelagicus based on genetic data, and this will be further elaborated on in the following general taxonomic discussion.