Amemboa (Amemboa) riparia Polhemus and Andersen

Figs. 17, 31

Amemboa (Amemboa) riparia Polhemus and Andersen 1984: Steenstrupia 90−92.

Amemboa (Amemboa) lyra (Paiva): Zettel and Chen 1997, Ann. Hist.-Natur. Mus. Nat. Hung. 156−157 (synonymy). Amemboa (Amemboa) riparia: Polhemus and Tran 2012, Zootaxa 55−57 (stat. nov.)

Diagnosis. Males of A. riparia have the pygophore with a pair of small posterolateral lobes and a digitate tip (Fig. 31). Further, the male profemur has two distinct hair patches (Fig. 17), whereas A. javanica has a single hair patch, and A. aquafrigida and A. speciosa each have three hair patches. Males of A. riparia have a proximally incrassate profemur, whereas A. brevifasciata has an unmodified proximal half of the profemur. Males of A. riparia have a well-developed profemoral tumescence beyond the proximal hair patch, whereas those of A. cristata lack the midventral tumescence.

Discussion. Polhemus & Andersen (1984) described A. riparia based on specimens from Chiang Mai. They described the similarities between A. riparia and A. lyra (Paiva), and distinguished them by the number of hair patches on the profemur in males. More specifically, males of A. lyra have the profemur with a small middle patch on a tumescence, whereas males of A. riparia lack the middle patch. Later, Zettel & Chen (1997) synonymized A. riparia with A. lyra because the hair patches vary within and among populations in both species, and the male genitalia of both species are not clearly distinguishable. More recently, Polhemus & Tran (2012) reestablished A. riparia and stated that it can be distinguished from A. lyra by the structure of the male fore leg and pygophore. Moreover, the presence of a middle hair patch on the fore leg in A. riparia is variable and can occur at a low frequency (Polhemus & Tran 2012). This species has been recorded from Laos, peninsular Malaysia, Singapore, Thailand, and Vietnam (Polhemus & Andersen 1984, Cheng et al. 2006, Zettel et al. 2007). In Thailand, this species has been collected previously from Chiang Mai, Mae Hong Son, Nan, Phetchabun, Phrae, Songkhla, and Tak provinces (Polhemus & Andersen 1984, Zettel & Chen 1997, Vitheepradit 2000). This species was collected throughout the Phetchabun Mountain Range and in various types of habitats (e.g., rock pools, leaf packs, muddy tire ruts, sandy stream margins). Also, we have observed variation in presence or absence of the small middle hair patches on male profemora in specimens collected from Heuy Prom Laeng, Nam Nao NP, Chaiyaphum Province. This species occurred synoptically with A. aquafrigida in rock pools in Loei and Phitsanulok provinces.

Material examined. THAILAND: Loei Province: Amphur Phu Rua, Plan Ba Waterfall, 17°23'N 101°22'E, 649 m, 10-V-2004, A. Vitheepradit and T. Prommi, L-675 (3 winged males, 1 wingless male, 2 winged females, 1 wingless female); Chaiyaphum Province: Phu Kiew WS, Lam Nam Prom, 16°27'N 101°39'E, 589 m, 2-V-2004, A. Vitheepradit, L-656 (1 winged male); Nam Nao NP, Heuy Prom Laeng, 16°38'N 101°034'E, 802 m, 20-XII- 2012, KU team, C-239 (1 winged male); Phetchabun Province: Khao Kho NP, Lam Nam Khek, 16°34'N 100°58'E, 760 m, 20-VIII-2012, KU team, C-178 (1 winged male, 1 winged female); Phitsanulok Province: Thung Salaeng NP, Huai Tub Dah Mi, 16°50'N 100°51'E, 440 m, 8-III-2002, R.W. Sites, A. Vitheepradit and K. Kirawanich, L-274 (3 winged males, 4 winged females); same locality, 13-V-2004, A. Vitheepradit and T. Prommi, L-683 (9 winged males, 1 wingless male, 7 winged females); Thung Salaeng NP, Kaeng So Pha, 16°50'N 101°51'E, 397 m, 11-V-2004, A. Vitheepradit and T. Prommi, L-679 (1 winged male).