Thursday, August 11, 2016

[Crustacea • 2016] Indochinamon chuahuong • A New Species of the Genus Indochinamon Yeo & Ng, 2007 (Brachyura: Potamidae) from northern Vietnam

 Indochinamon chuahuong 
Do, Nguyen & Le, 2016

 A new species of potamid freshwater crab, Indochinamon chuahuong, is described from Ha Noi, northern Vietnam. The new species can be distinguished from all other Indochinamon species by a suite of characters, including a carapace broader than long; an anterolateral margin that is convex and distinctly serrated; longer ambulatory legs than its congeners; and the terminal segment of the male first gonopod being curved outwards, with a very low dorsal flap.

Key words. Vietnam, Crustacea, Brachyura, Potamidae, new species, taxonomy



Family Potamidae Ortmann, 1896
Subfamily Potamiscinae Ortmann, 1896 (sensu Yeo & Ng, 2003)

Indochinamon Yeo & Ng, 2007

Indochinamon chuahuong, new species

Diagnosis. Carapace broader than long (mean 1.4 times), anterolateral margin convex, distinctly serrated; the brachial region slightly swollen when viewed dorsally. Ambulatory legs relatively long. G1 broad, gently sinuous; terminal segment relatively short, about 0.4 times the length of the subterminal segment, about 3.3 times longer than broad, distally curved outwards, outer margin swollen at base, with very low, narrow dorsal flap.

Size. This species is quite large, with the largest recorded male specimens measuring 76.1× 53.0 mm. From what has been published, Indochinamon chuahuong is one of largest freshwater crabs known from Vietnam (Yeo & Ng, 2007; Nasure et al., 2011; Dang & Ho, 2012).

Etymology. The new species is named after the type locality, Chua Huong. The name is used as a noun in apposition.

Remark. This new species can be separated from congeners by a suite of characteristics, including broader carapace; distinctly serrated, convex anterolateral margin; long ambulatory legs; G1 terminal segment curved outwards, with very low dorsal flap visible only from dorsal. Nevertheless, the most important characters that distinguish the new species from the other species of the genus Indochinamon are the prominently serrated anterolateral margins and the distinctly long ambulatory legs. Only four species of Indochinamon (I. chuahuong, I. bavi, I. kimboiense and I. phongnha) possess a dorsal flap (protuberance of ventral outer surface) at the terminal segment of the G1. However, I. chuahuong can be distinguished from the other three species by a combination of morphological characters (Table 1).

Carapace margin and longer legs of I. chuahuong are similar to Kanpotamon duangkhaei Ng & Naiyanetr, 1993 from northern Thailand. However, the shape of the G1 terminal segment differs in K. duangkhaei in the distinct bulbous structure on the proximal part of the G1’s outer margin. In addition, the suture between sternites 2 and 3 are gently concave in K. duangkhaei while convex in I. chuahuong. Habitat. Indochinamon chuahuong was collected from an innominate limestone mountain in a forest near the center of Chua Huong (Fig. 5A, B). This new species is believed to be semi-terrestrial, as it has been collected in wet forest habitats distant from local streams.

Van Tu Do, Tong Cuong Nguyen and Hung Anh Le. 2016. A New Species of the Genus Indochinamon Yeo & Ng, 2007 (Crustacea: Brachyura: Potamoidea: Potamidae) from northern Vietnam. RAFFLES BULLETIN OF ZOOLOGY. 64: 187–193.