Neduba oblongata Cole, Weissman, & Lightfoot 2021, sp. n.

Neduba oblongata Cole, Weissman, & Lightfoot sp. n.

Fig. 9. (distribution), Fig. 11 (male and female habitus, calling song, male and female terminalia, karyotype), Plate 4B (male calling song), Plate 6E (ventral sclerite), Plate 11B (female subgenital plate).

Common name. Mount Hamilton Shieldback. History of recognition. None.

Type material. HOLOTYPE MALE: USA, CA, Santa Clara Co., Mount Hamilton, 2.6 road mi. W observatory, 37.341883N, 121.643002W, 1036 m, 12-VI-1982, DB Weissman, S 82-23 [stop], R82-47 [recording], T82-2 [karyotype], 127 [teeth] 3.5 [mm stridulatory file length], deposited at CAS, Entomology type #19713.

PARATYPES (n=10): USA, CA, Santa Clara Co., 1♁, Mount Hamilton, 0.3 mi. W observatory, 37.341883N, 121.643002W, 1260 m, 6-VII-1997, DB Weissman, CAS; 3♁, Mount Hamilton, 15 mi. W observatory, 37.341883N, 121.643002W, 488 m, 12-VI-1982, DB Weissman, CAS; 3♁, 1♀, Mount Hamilton, 2.6 mi. W observatory, 37.341883N, 121.643002W, 1036 m, 12-VI-1982, DB Weissman, CAS; 2♁, Mount Hamilton, 6.5 mi. W observatory, 37.32864N, 121.65729W, 686 m, 8-VIII-2015, DB & DW Weissman, LACM

Measurements. (mm, ♁n = 8, ♀ n = 1) Hind femur ♁18.44–20.61, ♀ 22.01, pronotum total length ♁8.65–11.01, ♀ 9.66, prozona length ♁3.65–5.21, ♀ 4.95, metazona dorsal length ♁4.80–6.27, ♀ 4.71, pronotum constriction width ♁2.50–3.14, ♀ 3.55, metazona dorsal width ♁6.00–7.39, ♀ 6.43, head width ♁4.26–4.85, ♀ 5.18, ovipositor length ♀ 18.58.

Distribution. Known only from Mount Hamilton in the Diablo Range, Santa Clara County, California.

Habitat. Oak woodland and chaparral.

Seasonal occurrence. Available records indicate adult activity extends throughout the summer from mid-June (12-VI-1982, DB Weissman, CAS) through mid-August (8-VIII-2015, DB & DW Weissman, CAS).

Stridulatory file. (n = 4) length 2.8–3.5 mm, 114–134 teeth, tooth density 39.1 ± 2.3 (36.3–41.3) teeth/mm.

Song. (n = 9) Unique. PTR is bimodal and switches between a slow rate 7.45 ± 0.59 s- 1 and a fast rate of 11.2 ± 1.28 s- 1.

Karyotype. (n = 4) 2n♁ = 26 (2m + 22t + XtYt), S82-23, T82-2, paratopotype.

Recognition. Stridulatory file, male genitalia, song, and geography. A low stridulatory file tooth density separates this species (36–41 teeth/mm) from N. carinata, which has a significantly higher density (38–55 teeth/mm; two-sample t -test, P = 0.007). The ventral sclerite is robust with a straight shaft, low convex apex, and a minute lateral process. Other Carinata Group species have a longer lateral process, and the shaft of Convexa Clade species is curved. Santa Lucia Mountains N. carinata males may have a minute lateral process but the whole sclerite is not as robust as in N. oblongata. The ventral sclerite of N. diabolica, which inhabits the same mountain range, has a more conical apex, a longer lateral process, and a curved shaft. The calling song is unique among Carinata Group species in having a bimodal PTR. The female subgenital plate is pentagonal and flat, identical to N. carinata, both of which are separated from N. diabolica by the lack of a medial groove. This species is geographically restricted to the Mount Hamilton vicinity in the Diablo Range of California.

Etymology. l. oblongata oblong, referring to the fusiform habitus and enlarged, oval pronotum.

Notes. The two highest peaks in the Diablo Range, Mount Hamilton (1284 m) and Mount Diablo (1173 m) are mountain habitat islands separated by a mere 67 km, yet each harbors a distinct Carinata Group species (see N. diabolica below). This contrasts with a single (albeit variable) species, N. carinata, distributed across 200 km of the South Coast Ranges. The Santa Clara Valley is thus implicated as an isolating barrier between the Diablo Range and the Coast Ranges, while the Vallecitos Valley is a potential biogeographic break between populations in the north and south of the Diablo Range. The bimodal PTR in the male calling song is reminiscent of the songs of Sierranus Group species (see below). Given the evolutionary distance between the Carinata Group and the Sierranus Group (Figs. 3–5), the mostly likely explanation for shared bimodal PTR is convergent evolution. A preexisting receiver response may exist in Neduba females (e.g. Basolo 1996; Ryan & Rand 1999) that selects for male songs with an elaborate pattern or additional OPT.

Material examined. Type series only. See Type material above.