Gracilentulus macrotarsus Nakamura 2021, sp. nov.
Creators: name: Nakamura, Osami
Publisher: name: Zenodo
Year: 2021
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Entognatha
Protura
Acerentomidae
Gracilentulus
Gracilentulus macrotarsus

description: Gracilentulus macrotarsus sp. nov.
Figs. 1–3, Table 1
Materials examined. Holotype: one female (NSMT-Ap 556), Nishi Park, Chûô-ku, Fukuoka-shi, Fukuoka Prefecture, evergreen broad-leaved forest dominated by Castanopsis sieboldii, 33.5981º N, 130.3746º E, elev. 5 m, 18-VII-2005, T. Kubota leg.
Paratypes: two preimagines (male) (NSMT-Ap 557–558), same data as for the holotype.
Other materials examined: one maturus junior (NSMT-Ap 559), same data as for the holotype.
All specimens including holotype (NSMT-Ap 556) and paratypes (NSMT-Ap 557–558) are deposited in NSMT.
Diagnosis. Foretarsal sensilla c and d same level with t2, c closer to d, a’ distal to t1; P1a and P2a on thoracic tergites II–III small lanceolate; P3 on abdominal tergite VI same row with other posterior setae; P3a present on abdominal tergites VI–VII; seta P1a present on tergite VI.
Description. Body length 949 μm. Head length 123 μm, width 90 μm; labrum short, 5 μm, LR = 27; cephalic setae l3, l5, sd4, sd5 short setiform, 5 μm; seta d6 present; seta sd7 1.3 times longer than d7 (Fig. 1A). Maxillary palpus with two sensilla on penultimate segment, dorsal and ventral sensilla similar in shape and length (Fig. 1B). Labial palpus reduced to three setae and one sensillum (Fig. 1C). Canal of maxillary gland simple, proximal part short, CF = 8 (Fig. 1D). Pseudoculus slightly broader than long, 7 μm x 9 μm, PR = 16 (Fig. 1E). Pore fp present (Fig. 1A).
Foretarsus (Figs. 2A–C) 109 μm long; claw 30 μm, TR = 3.6; empodium 3 μm, EU = 0.1. Dorsal sensillum t1 claviform, almost level with α3, BS = 0.4; t2 thin, longer than c and d; t3 small knob-like, its apex not pointed. Exterior sensillum a surpassing base of d; b longer than c and d; c and d close to each other, subequal in length, situated at same level with t2; e situated about halfway between γ3 and α5, its apex surpassing base of α7; f at about halfway between e and g, its apex reaching base of γ5; g at same level with t3, its apex reaching base of claw. Interior sensillum a' broad, distal to t1; b' absent; c' not surpassing tarsus. Single pore present between α3 and a, and between t3 and g. Seta β1 sensillum-like, δ1–5 short, δ5 proximal to δ4. Middle tarsus 46 μm, its claw 21 μm; hind tarsus 59 μm, its claw 22 μm.
Body chaetotaxy as in Table 1 and Figs.3A–C. On thoracic tergites II–III (Fig. 3A), P1a and P2a lanceolate microchaetae; P1a almost halfway between P1 and P2; P2a slightly nearer to P3 than to P2; P5a rudimentary; 1 and 2 on thoracic tergite I 33 and 13 μm; P1, P1a and P2 on thoracic tergite II 33, 3 and 39 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) (Fig. 3B, C). P3 on abdominal tergites II–V situated anterior to other posterior setae; P3 on VI–VII in the same row with other posterior setae (Fig. 3B). Accessory setae, P1a, P2a and P4a, present on abdominal tergites II–VII; P3a on VI–VII; these setae short and less than about 1/6 of P 1 in length; P1a close to P1; P2a near to P2 (Fig. 3B, C). Sternite VIII with a single row of four setae (Fig. 3C). Accessory setae, P1a, on abdominal sternites I–VII similar to dorsal accessory setae. P1, P1a and P2 on abdominal tergite VI 36, 5 and 43 μm; P1, P1a and P2 on VII 37, 5 and 39 μm.
Thoracic tergite II with pores sl and al (Fig. 3A); III with sl. Pore psm present on abdominal tergites I–VIII, those on VIII without accompanying teeth; psl on VI–VII (Fig. 3B); al on II–VII (Figs. 3C, D). Sternites V with two sam; IV–VI with spsm; VII with asymmetrical spsm (Fig. 3C).
Abdominal appendage II–III each with two setae, apical seta less than a half of subapical one (Fig. 1F). On abdomen VIII, striate band developed, striae distinct (Fig. 3B, C); comb rectangular with 8 teeth (Fig. 1G). Female squama genitalis with stout pointed acrostylus (Fig. 1H).
Preimago (male). Body length 780 μm in extended condition. Head length 101–105 μm, width 76 μm, LR = 26–27, CF = 8–9, pseudoculus circular, 8–9 μm x 8–9 μm, PR = 12–13. Foretarsus 86 μm; claw 26 μm, TR = 3.3; empodium 3 μm, EU = 0.1; BS = 0.4. Middle tarsus 38–39 μm, its claw 15–18 μm; hind tarsus 18–20 μm, its claw 18–20 μm. Fundamental features almost same with those of imago. P1, P1a and P2 on thoracic tergite II 21–26, 2–3 and 33–34 μm; P1, P1a and P2 on abdominal tergite VI 32–37, 4 and 35–36 μm; P1, P1a and P2 on VII 32, 4 and 34–35 μm.
Maturus junior. Body length 533 μm. Head length 103 μm, CF = 10, pseudoculus 7 μm x 7 μm, PR = 14. Fore- tarsus 80 μm; claw 24 μm, TR = 3.4; empodium 3 μm, EU = 0.1. Shape and position of foretarsal sensilla same as those of preceding stages, BS = 0.4. Middle tarsus 35 μm, its claw 14 μm; hind tarsus 40 μm, its claw 19 μm. Seta Mc present instead of M1 on abdominal tergite VIII and the following setae absent: P1a on abdominal tergites II–VI, A4 on tergite VI, 4a on tergite IX, 1, 2, and 3a on tergite X, and 2 and 3 on sternite XI
Chaetotaxic variation. Asymmetric absence of A1 on abdominal tergite VI in maturus junior.
Remarks. The present new species is similar to G. maijiawensis Yin & Imadaté from China in the position of foretarsal sensilla b, c, and d on nearly line, and d close to c, as well as the anterior setae on abdominal tergites II–VII (Yin & Imadaté 1979); however, it differs from G. maijiawensis by the length of foretarsal sensillum a' (long and surpassing δ 3 in G. maijiawensis), the presence of dorsal accessory setae P3a on abdomen VI (absent in G. maijiawensis), and the position of P3 on VI (anterior in G. maijiawensis).
This species also resembles G. chichibuensis from Japan and G. shippingensis Yin from China in the shape of the accessory setae on thoracic tergites II–III (small and lanceolate) and the position of P3 on abdominal tergite VI in same row as the other posterior setae (Nakamura 1995). However, the new species differs from both established species by the setae on the labial palpus (four setae in the two established species), from G. chichibuensis by the position of t2 (distal to c and d in G. chichibuensis) and P3a on abdominal tergite VI (absent in G. chichibuensis), and from G. shippingensis by the chaetotaxy of abdominal tergite VII (eight anterior setae in G. shippingensis) and the position of a’ (almost level with t 1 in G. shippingensis).
Distribution. Japan (Kyushu), known only from the type locality.
Etymology. The species name is derived from the long foretarsus within the genus.
description: Published as part of Nakamura, Osami, 2021, The Japanese species of the genus Gracilentulus (Protura: Acerentomidae), pp. 271-294 in Zootaxa 4991 (2) on pages 272-277, DOI: 10.11646/zootaxa.4991.2.3, http://zenodo.org/record/5030484