Gracilentulus microtrichus, Nakamura, 2021

Nakamura, Osami, 2021, The Japanese species of the genus Gracilentulus (Protura: Acerentomidae), Zootaxa 4991 (2), pp. 271-294 : 277-281

publication ID	https://doi.org/ 10.11646/zootaxa.4991.2.3
publication LSID	lsid:zoobank.org:pub:943B6E49-37EB-40BE-B0EE-39D87CEEF7BA
DOI	https://doi.org/10.5281/zenodo.5030259
persistent identifier	https://treatment.plazi.org/id/252BDE55-166F-FFC5-D285-FD9DFA3ADB86
treatment provided by	Plazi
scientific name	Gracilentulus microtrichus
status	sp. nov.

Treatment

Gracilentulus microtrichus sp. nov.

Figs. 4–7 View FIGURE 4 View FIGURE 5 View FIGURE 6 View FIGURE 7 , Table 2 View TABLE 2

Materials examined. Holotype: female (NSMT-Ap 560), Mt. Koma-ga-take, Kanegasaki-machi, Iwate Prefecture, deciduous broad-leaved forest of Fagus crenata and Clethra barbinervis with herb layer of Sasa kurilensis , 39.185816º N, 140.934838º E, elev. 710 m, 18-VIII-2001, O. Nakamura et al. leg.

Holotype (NSMT-Ap 560) is deposited in NSMT.

Diagnosis. Foretarsal sensilla a–g broad; b subequal to c and d in length, base of c closer to d, f close to e; proximal part of canal of maxillary gland short and large end dilatation; cephalic setae s d4, sd5, accessory setae on thoracic segments II–III and abdominal segments I–VII oblong microchaetae. Seta A4 present on thoracic sternite II. Seta P1a absent on tergite VI. Pores lt present on V–VI.

Description. Body length 1,079 μm. Head length 148 μm, width 98 μm, labrum not protruded; cephalic setae l3, l5 short setiform, 5 and 7 μm, respectively; sd4 and sd5 oblong microchaetae ( Fig. 4E View FIGURE 4 ), 3 μm; d6 present; sd7 1.6 times longer than d7 ( Fig. 4A View FIGURE 4 ). Maxillary palpus with two broad sensilla on penultimate segment, dorsal and ventral sensilla similar to each other in shape and length, 8 μm ( Fig. 4B View FIGURE 4 ). Labial palpus with three setae and one sensillum ( Fig. 4C View FIGURE 4 ). Canal of maxillary gland simple, proximal part short and stout with large end dilatation ( Fig. 4D View FIGURE 4 ). Pseudoculus longer than wide, 12 μm x 9 μm, PR = 13 ( Fig. 4E View FIGURE 4 ). Pore fp present ( Fig. 4A View FIGURE 4 )

Foretarsus ( Figs. 5A, B View FIGURE 5 ) 97 μm, claw 22 μm, TR = 4.5, empodium 3 μm, EU = 0.1. Foretarsal sensilla a–g and a' broad; a, g and a' broader than other sensilla. Dorsal sensillum t1 claviform, same level with α3, BS = 0.5; t2 thin, distal to d; t3 small knob-like, its apex not pointed. Exterior sensillum a surpassing base of d; b, c, and d on nearly line; b subequal to c and d; c close to d, its apex reaching base of e; d surpassing base of e; e situated about halfway between γ3 and α5; f close to e; g at same level with t3; apices of e, f and g surpassing tarsus. Interior sensillum a' slightly distal to t1; b' absent; c' linear, its apex reaching base of claw. Single pore present between α3 and a, and between t3 and g, respectively. Seta β1 sensillum-like, δ1–5 short; δ5 proximal to δ4. Middle tarsus 36 μm, its claw 19 μm; hind tarsus 42 μm, its claw 20 μm.

Body chaetotaxy as in Table 2 View TABLE 2 and Figs. 6A–E View FIGURE 6 , 7A–D View FIGURE 7 . On thoracic tergites II–III ( Figs. 6A, B View FIGURE 6 ), P1a and P2a oblong microchaetae ( Fig. 6C View FIGURE 6 ); A2 and M2 on sternite I–III short oblong, same as dorsal accessory setae ( Fig. 6D, E View FIGURE 6 ). Seven anterior setae (Ac, A2, A3, A4) present on thoracic sternites II–III ( Fig. 6E View FIGURE 6 ). 1 and 2 on thoracic tergite I 20 and 13 μm; P1, 1a and P2 on thoracic tergite II 15, 2 and 22 μm. Abdominal tergites I–V with three pairs of anterior setae (A1, A2, A5); VI with four pairs (A1, A2, A4, A5); VII with three pairs (A2, A4, A5) ( Figs. 7A, B View FIGURE 7 ); P3 on abdominal tergites II–VI situated anterior to other posterior setae ( Figs. 7A, B View FIGURE 7 ). Posterior accessory setae on abdominal tergites I–VII oblong microchaetae and less than about 1/6 of P 1 in length, but P1a absent on VI; P1a nearer to P1 than to P2; P2a near to P3 ( Figs. 7A, B View FIGURE 7 ). P1a on abdominal sternites I–VII oblong microchaetae, same as dorsal ones ( Fig. 7D View FIGURE 7 ); VIII with a single two of four setae. P1, P2 and P2a on abdominal tergite VI 20, 25 and 3 μm; P1, P1a and P2 on VII 24, 3 and 27 μm.

Thoracic tergite II–III with pore sl ( Fig. 6A, B View FIGURE 6 ). Pore psm present on abdominal tergites I–VIII, those on VIII without accompanying teeth ( Fig. 7C View FIGURE 7 ); al on V–VII, lt on V–VI ( Fig. 7D View FIGURE 7 ). Sternites V–VII with spsm ( Fig. 7D View FIGURE 7 ).

Abdominal appendage II–III each with two setae, apical seta about 1/3 of subapical one in length ( Fig. 4F View FIGURE 4 ). On abdomen VIII, striate band developed, striae distinct ( Fig. 7C View FIGURE 7 ); comb rectangular with 7 teeth ( Fig. 4G View FIGURE 4 ). Female squama genitalis with stout pointed acrostylus ( Fig. 4H View FIGURE 4 ).

Remarks. The present new species differs from its congeners that are without foretarsal sensillum b’ by the position of foretarsal sensillum f (halfway between e and g in others) and the shape of the accessory setae on abdomen I–VII (normal setae in others). Among the congeners, only in the new species and G. floridanus (Ewing) does foretarsal sensillum b have a subequal length to c and d ( Tuxen 1964); however, this new species differs from G. floridanus in the chaetotaxy of abdominal tergites II–VI (eight anterior setae in G. floridanus ).

Distribution. Japan (Honshu), known only from type locality.

Etymology. The species name is derived from the microchaetae accessory setae on the thorax and abdomen.