Nebria (Sadonebria) yatsugatakensis, Sasakawa, Koji, 2016

Sasakawa, Koji, 2016, Two new species of the ground beetle subgenus Sadonebria Ledoux & Roux, 2005 (Coleoptera, Carabidae, Nebria) from Japan and first description of larvae of the subgenus, ZooKeys 578, pp. 97-113 : 100-105

Taxon classification Animalia Coleoptera Carabidae

Nebria (Sadonebria) yatsugatakensis sp. n. Figs 3, 7, 12-19, 20-21, 22-28, 29-30

Nebria sadona (part): Uéno (1985): 56, fig. 10.

Nebria (Orientonebria) sadona (part): Farkač and Janata (2003): 94.

Nebria (Sadonebria) sadona (part): Ledoux and Roux (2005): 822, fig. 618; Yoshitake et al. (2011): 37.

Type materials.

Holotype: ♂ (FZUT), Tamagawa, Minoto, Chino-shi [the Yatsugatake Mountains], Nagano Prefecture, Japan (35°58'52.6"N, 138°18'29.4"E; ca. a.l.t. 1600 m), 4-5.ix.2010, K. Sasakawa leg. Paratypes (KS): 2♂ 6♀, same locality (2♀, 15-16.ix.2009, K. Sasakawa & H. Ikeda leg.; 2♂ 4♀, 4-5.ix.2010, K. Sasakawa leg). Larval specimens (KS) are not designated as type materials.

Etymology.

The specific name is derived from the Yatsugatake Mountains, the type locality of the new species.

Diagnosis of adult.

Similar to locally adjacent species, such as Nebria chichibuensis Sasakawa, 2010 (Figs 7, 11; see also Fig. 1), but distinguished by the shape of the endophallus (for example, the dorsoapical lobe is clearly Y-shaped in Nebria yatsugatakensis but not in Nebria chichibuensis ). Distinguished from Nebria sadona by a pronotum line that reaches both the anterior and posterior margins, a feature that is absent in Nebria sadona near the anterior and posterior margins ( Sasakawa 2008).

Description of adult.

External structures: Body length (including mandibles): ♂, 11.7-12.9 mm (mean ± SD: 12.2 ± 0.58 mm, n = 3); ♀, 12.8-13.9 mm (mean ± SD: 13.3 ± 0.41 mm, n = 6). Head without a reddish-brown patch between eyes; pronotum entirely black, but lateral margins dark brown in some specimens; legs dark brown, except for the femora, which are brownish black.

Male genitalia: Laterobasal lobes markedly swollen; laterapical lobes superficial; dorsoapical lobe large, similar in size to the laterobasal lobe, with the apex bifurcated in a Y shape; dorsobasal lobe distinct but smaller than the laterobasal and dorsoapical lobes.

Diagnosis of larvae.

In older instars, distinguished from congeneric species by numerous setae on the entire surface of thoracic nota and abdominal tergites (see Discussion).

Description of larvae.

Characters present in all instars: head capsule dark-brown to brownish black, with lighter ventral side; mouthpart appendages and legs brown to light-brown; urogomphi light- to dark-brown; other scletites on thorax and abdomen gray to brownish-gray; membranous parts grayish white. Most primary setae and pores present, but at least the following ones absent: FR8, FR9, LA4, PR7, ME2, TE4, TE6, TE9, EM1, FRf, PAn, COd, TEb, and PYe. Head capsule oval, widest at stemmata. Frontale U-shaped at base, with posterior end at the level of basal 1/3 of head capsule; nasale prominent, with three pairs of large projections; adnasale sloping posterolaterally. Parietale with six stemmata; cervical groove absent; coronal suture present. Antennae longer than mandible; antenomeres I and III subequal in length, longer than II and IV. Mandible slender and arcuate, with sharp apex; terebra without tooth-like processes; retinaculum as long as the width of the mandible at the level of MN1 and curved inward, with sharp apex. Maxilla with stipe as long as palpomeres III and IV combined; palpomere II and III subequal in length, shorter than IV, and longer than I; membranous notch absent. Labium with cordate prementum and elongated ligula; palpomere I longer than ligula but shorter than palpomere II. Thoracic nota and abdominal tergites transverse; notal carina of meso- and metanotum and abdominal tergal carina distinct. All legs with two unequal claws, with the anterior claw longer than the posterior one. Urogomphi slender, longer than head capsule.

Characters restricted to first-instar larvae: head width 1.16-1.22 mm (mean ± SD: 1.20 ± 0.02 mm, n = 5). Urogomphi 1.59-1.72 mm (mean ± SD: 1.66 ± 0.05 mm, n = 5). Secondary setae present on maxilla (9-11 for gMX), pronotum (one on central part, and one on posterior part), and abdominal epipleurite (one on central part). Head capsule with longitudinal, keel-like egg-bursters. Antennomere II almost cylindrical, subequal in length to IV. Maxillary palpomere III less than half the length of IV. Pronotum with indistinct notal carina. Urogomphi fused to tergite IX.

Characters restricted to older instars: Head width 1.50-1.52 mm (mean ± SD: 1.51 ± 0.01 mm, n = 4) in second instar; 1.80-1.89 mm (mean ± SD: 1.85 ± 0.04 mm, n = 5) in third instar. Urogomphi 2.08-2.27 mm (mean ± SD: 2.19 ± 0.08 mm, n = 4) in second instar; 2.51-2.94 mm (mean ± SD: 2.77 ± 0.16 mm, n = 5) in third instar. Secondary setae present on antennomere I (two on inner side), maxilla (14-19 for gMX, and two near MXb), labium (one behind LA3), frontale (absent or less than two near FRe and/or about three around FR1-3), and epimeron (absent or less than two); parietale, thoracic nota, abdominal tergites, epusterna, epipleurites, pleurites, sterna, pygidium, urogomphi, legs except claws with numerous secondary setae on entire surface. Antennomere II longer than IV, with the distal end being distinctly wider than the proximal end. Maxillary palpomere III more than half the length of IV. Pronotum with notal carina distinct. Urogomphi not fused to tergite IX.

Remarks.

For larvae reared at 5°C, the number of days (mean ± SD) of the first and second instars were 25.50 ± 2.25 (n = 16) and 42.50 ± 1.87 (n = 6), respectively. For larvae reared at 10°C, the durations of first and second instars were 15.29 ± 0.61 (n = 14) and 22.13 ± 2.30 (n = 8).