Baculentulus krabbensis, Bu, Yun, Potapov, Mikhail B. & Yin, Wen Ying, 2014

Bu, Yun, Potapov, Mikhail B. & Yin, Wen Ying, 2014, Systematic and biogeographical study of Protura (Hexapoda) in Russian Far East: new data on high endemism of the group, ZooKeys 424, pp. 19-57: 20-23

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Baculentulus krabbensis

sp. n.

Taxon classification Animalia Protura Berberentulidae

Baculentulus krabbensis  sp. n. Figs 2, 3; Table 1

Material examined.

Holotype, female (No. FE-2011022-2) (SEM), Russia, Far East, Primorsky Krai, Khasansky area, eastern part of Krabbe Peninsula, from mixed samples of soil and moss under a broad-leaved forest on a hill beside the coast, 42°37.40'N, 130°52.35'E, 16-IX-2011, coll. Y. Bu, C. W. Huang, M. Potapov & V. Alpatov. Paratypes, 2 females (Nos. FE-2011022-1, FE-2011023) (SEM; MSPU), 1 maturus junior (No. FE-2011022-3) (SEM), same data as holotype.


Adult body length 1000-1100 µm (n=3), pale yellow in color (Fig. 3A).

Head (Fig. 2A). Ovate, length 90-110 µm, width 70 µm. Setae d 6 present, sd4 and sd5 short sensilliform. Setae d6 11 µm, d7 10 µm and sd7 19 µm in length. Clypeal pore cp and frontal pore fp present. Pseudoculus round, length 7-8 µm, with short posterior extension, PR=15 (Fig. 2B). Calyx of maxillary gland smooth, without any appendix, blind end split into two leaves, posterior filament 15 µm, CF=7 (Fig. 2C). Maxillary palpus with two tapering sensilla, subequal in length (Fig. 2D). Labial palpus reduced, with three setae and one lanceolate basal sensillum (Fig. 2E).

Foretarsus (Fig. 2G, H). Length 80 µm, claw length 20 µm, without inner flap, TR=4; empodium length 3 µm, EU=0.15. Dorsal sensilla t-1 baculiform, t-2 slender and long (17 µm), BS=0.33, t-3 broad-leaf shape. All other exterior sensilla slender, except broadened sensillum g, a surpassing base of b and c, b broad at base and extremely long (29 µm), reaching base of γ 4, c nearly reaching base of e and slightly lower than b and d, d located at same level to b, e short, f long, g broad and short. Interior sensilla a’ lanceolate and broad, b’ absent, c’ reaching base of claw. Relative length of sensilla: t1 = t3 < a’ < (g = t2 = c’) < a < (c = e) < d < f < b. Setae β 1 and δ 4 sensillum, 6 µm and 7 µm respectively. Pores close to base of sensilla a and t3 present. Length of middle tarsus 35 µm, claw length 15 µm. Length of hind tarsus 38 µm, claw length 18 µm.

Thorax. Thoracic chaetotaxy given in Table 1. Setae 1 and 2 on pronotum 16 µm and 12 µm length respectively, mesonotum and metanotum with eight pairs of P-setae, accessory setae short sensilliform; setae P1, P1a and P2 on mesonotum 15 µm, 3 µm and 20 µm respectively (Fig. 2I). Prosternum with two pairs of anterior seta, and setae A2 and M2 sensilliform (Fig. 3B). Mesosternum and metasternum each with 7 A-setae, and setae A2 sensilliform (Fig. 3C, D). Pronotum and prosternum without pores (Figs 2I, 3B). Mesonotum with pores sl and al, metanotum with pores sl only (Fig. 2I). Mesosternum and metasternum without pores (Fig. 3C, D). Single membranal pore present on membrane between each coxa and the body.

Abdomen. Abdominal chaetotaxy given in Table 1. Tergite I with three pairs of anterior setae (A1, A2, A5) and six pairs of posterior setae (Fig. 2K). Tergites II–VI with eight pairs of posterior setae. Tergite VI and VII with four pairs of anterior setae (A1, A2, A4, A5). Tergites VII with nine pairs of posterior setae, P3a present. All accessory setae on tergites I–VII sensilliform, 5-6 µm on tergites I–VI and 7 µm on VII. Tergite VIII with paired setae M1 (Fig. 3G). Sternite IV–VII each with eight posterior setae, Pc absent (Fig. 3H, I, J). Sternite VIII with 4 setae.

Tergites I and VIII with pores psm only (Figs 2K, 3G), II–V with pores psm and al (Fig. 3E), VI–VII with pores psm, al and psl (Fig. 3F), IX–XI without pores, XII with single medial pore. Sternites I–III without pores, IV with 1+1 anteromembranal pores, V and VI each with 1+1 posterior pores anterior to seta P1 and 1+1 anteromembranal pores (Fig. 3H, I), VII with single posterior pore asymmetrical located left or right and 1+1 anteromembranal pores (Fig. 3J), VIII–XI without pores, XII with 1+1 pores al.

Abdominal appendages I, II, III with 2, 1, 1 segments and 4, 2, 2 setae respectively. On appendages II and III, subapical seta 15-17 µm, apical seta 11-12 µm in length. Striate band on abdominal segment VIII reduced, anterior margin regular wave shaped (Fig. 3G). Comb on abdomen VIII rectangular, with 12-13 teeth (Fig. 2J). Female squama genitalis with very short basal apodeme, extremely long and pointed acrostyli (Fig. 2F). Male unknown.


The species is named after Krabbe Peninsula where the type specimens were collected.


Known only from type locality.


Baculentulus krabbensis  sp. n. is characterized by extremely long sensilum b on foretarsus, sensillum a’ located distal to t1, sensillum b’ absent, eight A-setae on tergite VI and VII, presence of P3a on tergite VII, and special female genitalia with short basal apodeme.


We placed the present new species in the genus Baculentulus  because the baculiform sensillum t1 on foretarsus, reduced labial palpus with three setae and one sensillum, smooth calyx of maxillary gland, reduced striate band, two pairs of anterior setae on mesonotum and metanotum, abdominal appendages II and III each with two setae of different length, and only 4 setae on sternite VIII. It is similar to Baculentulus samchonri  ( Imadaté & Szeptycki, 1976) from North Korea in having eight A-setae on both tergites VI and VII, absence of sensillum b’ and extremely long sensillum b on foretarsus. They can be distinguished by the posterior setae on tergite VII (9 pairs of P-setae with P3a present in Baculentulus krabbensis  sp. n. vs. 8 pairs of P-setae with P3a absent in Baculentulus samchonri  ), the anterior setae on tergite I (6 A-setae in Baculentulus krabbensis  sp. n. vs. 4 in Baculentulus samchonri  ), the length of sensillum f (extremely long and surpassing the base of claw in Baculentulus krabbensis  sp. n. vs. short and not reaching base of claw in Baculentulus samchonri  ), and the shape of female squama genitalis (basal apodeme very short in Baculentulus krabbensis  sp. n. vs. basal apodeme in moderate length in Baculentulus samchonri  ).