Bioacoustics of Neduba duplocantans

Etymology. l. duplo “twice as much, double” + cantans “singing,” referring to the rate of PT production that is twice as fast as a sympatric congener. Notes. This species was discovered by song while collecting a series of N. sequoia , and its distinctiveness was appreciated further when cytogenetic analysis revealed a distinct karyotype. The discovery of two morphologically cryptic Sequoia Group species ( N. duplocantans and N. sequoia ) that are both sympatric and syntopic is of considerable evolutionary interest. The species pair has diverged in several aspects: calling song, karyotype, and phenology. The calling song PTR differed by a factor of two. Considering the remarkably different songs and distinct karyotypes, stasipatric and secondary contact hypotheses should be tested in the Sequoia Group. With N. duplocantans adult activity commencing before N. sequoia have matured, allochronic isolation may also be evolving between the two species. Two females among the paratype series were identified through rDNA sequence ( Figs. 4-5 ). Introgression of mtDNA among the Sequoia Group species ( Fig. 4 ) is expected if young, geographically proximal species have a history of hybridization as observed in Aglaothorax (Cole 2016) .

Distribution. At present, known only from the vicinity of the Kaweah River in the Sequoia National Forest. Habitat. Found in tangles and among grass along a stream flowing out of a side canyon. Also collected on bushes along the road paralleling the Kaweah River. Seasonal occurrence. Males were active and females were a mixture of last instar nymphs, teneral adults, and mature adults in late June ( 25-VI-2017 , JA Cole & W Chatfield-Taylor, LACM). By August this species was rare ( 12-VIII-2015 , JA Cole, LACM). This species may be active earlier in the season than sympatric N. sequoia . Stridulatory file. (n = 7) length 2.7–3.4 mm , 126–173 teeth, tooth density 51.0 ± 4.9 (45.8–60.7) teeth/mm. Song. (n = 7) Unique. The PTR of 5.1 ± 0.3 s- 1 is much faster than any other Sequoia or Sierranus Group species, and twice as fast as sympatric N. sequoia . The MPTL is brief at 72.3 9.1 ms. The short MPTL contributes to a low PTdc of 35.8 ± 4.9%. PTF of 17.0 ± 1.0 kHz is higher than other Sequoia Group species and is difficult to hear except at short range. Karyotype. (n = 3) 2n♁= 21 ( 18t + XtXtYm), shared with N. sierranus , JCT 15-12, paratopotype. Recognition. Male N. duplocantans are separated from sympatric N. sequoia by stridulatory file tooth density (47–52 teeth/mm vs. 55–59 teeth/mm, respectively). To the north, N. inversa has a similarly constricted pronotum but that species also has a higher tooth density (64–68 teeth/mm). Male N. prorocantans to the south have similar stridulatory files but have a weakly constricted pronotum. The fast song PTR is unique, and readily separates this species by ear from syntopic N. sequoia as well as from neighboring N. prorocantans to the south, as well as N. inversa to the north due to the multiple OPT in that species. Adult activity apparently commences earlier in the season than N. sequoia in areas where they co-occur, but the two species may be found together in midsummer.