Bioacoustics of Huananpotamon amicitiae

Remarks. Huananpotamon amicitiae sp. nov. fits well with morphological descriptions of the genus, including the dorsal surface of the carapace being slightly convex, with fine rugae on the epibranchial regions, the exopod of third maxilliped possessing a well-developed flagellum, the male pleon being relatively narrow and acutely triangular in shape, the G1 is relatively long, slender, with the distal part of the subterminal segment slender, and the distal part of the terminal segment expanded to form a lobe, flap or similar projection ( Dai & Ng 1994 ; Dai 1999 ). The new species, H . amicitiae sp. nov. , possesses an elongated outer-distal angle of the G1 terminal segment ( Figs. 3B , 5A ), a distinctive character shared with nine congeners from nearby regions ( Fig. 7 ): H. angulatum ( Dai, Chen, Song, Fan, Lin & Zeng, 1979 ) , H . chongrenense Dai, Zhou & Peng, 1995 , H . guixiense Dai, Zhou & Peng, 1995 , H . koatenense ( Rathbun, 1904 ) , H . lichuanense Dai, Zhou & Peng, 1995 , H . lini Cheng & Li, 2008 , H . medium Dai, Zhou & Peng, 1995 , H . sheni Cheng & Li, 2008 , H . yiyangense Dai, Zhou & Peng, 1995 (cf. Cheng et al . 2008 : fig. 1(8); Dai & Ng 1994 : fig. 1; Dai et al . 1995 : figs. 1(4)–7(4)). The very high and well-developed inner-distal angle of the G1 terminal segment of H . amicitiae sp. nov. ( Figs. 3G , 5B ), however, is a distinguishing character, and is a feature shared only with H . koatenense ( Fig. 5C ; cf. Wang et al . 2022b : fig. 5B, C) and H . lini ( Fig. 5E ; cf. Cheng et al . 2008 : fig. 1(7), (8)). Huananpotamon amicitiae sp. nov. can be clearly differentiated from H . lini by the following characters: G1 reaching suture between thoracic sternites 4/5 ( Fig. 2D ) (versus G1 exceeding pleonal locking tubercle in situ , but not reaching suture between thoracic sternites 4/ 5 in H . lini ; cf. Cheng et al . 2008 : fig. 1(7)); G1 terminal segment with inner-distal angle relatively high, globular in shape ( Figs. 3B, G , 5B ) (versus inner-distal angle relatively low, somewhat blunt in H . lini ; Fig. 5E, F ; cf. Cheng et al . 2008 : fig. 1(8)); G1 terminal segment with outer-distal angle more elongate ( Figs. 3B, G , 5A ) (versus terminal segment outer-distal angle relatively shorter in H . lini ; Fig. 5E, F ; cf. Cheng et al . 2008 : fig. 1(8)); and G1 terminal segment with outer-distal angle strongly recurved and relatively thick in lateral view ( Fig. 5B ) (versus outer-distal angle slightly recurved and relatively more slender in lateral view in H . lini ; Fig. 5F ; cf. Cheng et al . 2008 : fig. 1(7), (8)). Other more subtle differences in the external orbital angle, postorbital cristae, and vulva are listed in Table 1 . Huananpotamon koatenense was described from one female (MNHN-IU-2014-23011), which had been incorrectly placed in Sinopotamon Bott, 1967 . In a previous study, we collected a series of specimens from the type locality and identified them as H . koatenense , and then the author redescribed the species and resolved its taxonomy (see Wang et al . 2022a ). We compared the detailed photographs of the type specimen of H . koatenense with the female H . amicitiae sp. nov. specimens from Yugan County. Huananpotamon amicitiae sp. nov. clearly differs from H . koatenense by the external orbital tooth being acutely triangular ( Fig. 4A–C ) (versus external orbital tooth broadly triangular in H . koatenense ; Fig. 4F–H ), and the epibranchial tooth is relatively larger, more rounded, and separated from the external orbital tooth by a broadly U-shaped cleft ( Fig. 4A–C ) (versus epibranchial tooth relatively smaller, granular, separating from external orbital tooth by narrow V-shaped cleft in H . koatenense ; Fig. 4F–H ). Huananpotamon amicitiae sp. nov. can be distinguished from H . koatenense by the following characters: G1 terminal segment with inner-distal angle relatively higher, globular in shape ( Figs. 3B, G , 5A, B ) (versus terminal segment with inner-distal angle relatively lower, globular in shape in H . koatenense ; Fig. 5C, D ), and outer-distal angle strongly curved ventral-ward and relatively thin in lateral view ( Fig. 5B ) (versus outer-distal angle almost straight and relatively thick in lateral view in H . koatenense ; Fig. 5D ). Other subtle differences existing in the postorbital cristae, cleft between external orbital angle and epibranchial tooth are listed in Table 1 .