Ceratrimeria takaoensis (Kinoshita, 1916)

Babenko, A. B., Nakamori, T., Ohira, A. & Potapov, M. B., 2021, The genus Ceratrimeria Bӧrner, 1906 (Collembola: Neanuridae, Pseudachorutinae) in the fauna of Japan, Far Eastern Entomologist 442, pp. 18-32 : 21-24

Ceratrimeria takaoensis (Kinoshita, 1916)

Figs 1–2 , 11 –21

Pseudachorutes takaoensis Kinoshita, 1916: 495 (type locality: Japan, Honshu , Mt. Takao).

MATERIAL EXAMINED. Topotypes (14 ex.): Japan, Honshu Island , Tokyo Prefecture ,

Hachioji city, Mt. Takao, 485 m alt., 35.6225° N, 139.2452° E, rotten wood, 24.VII 2017 , 4

ex., T. Nakamori leg. ; the same locality, 28. VIII 2019, 8 ex., A. Ohira, M. Kataoka & T .

Nakamori leg.; the same locality, 25. VI 2021, 2 ex., A. Ohira & T . Nakamori leg. Other material: Japan, Honshu Island , Nagano Prefecture, E Chino city, Kitayama, surroundings of

Mugikusa Hutte, GPS 93: 2037 m alt., 36.0544° N, 138.3326° E, humid valley forest with old Abies trees, litter & turf ( Lycopodium , Carex , Polytrichum ), under bark, 12. VIII 2016, 8

ex. (No 2016-46 R); the same site and date, but GPS 94: 2029 m alt., 36.0540° N , 138.3318°

E, 2 ex. (No 2016-50 R) and 5 ex. (No 2016-51 R), under Abies bark. All M. Potapov & N .

Kuznetsova leg.

DNA BARCODE. Three specimens each from Mt. Takao (the type locality, 35.6225° N,

139.2452° E, 24.VII 2017) and Chino (36.0544° N, 138.3326° E, 12.VIII 2016) were barcoded.

Museum voucher numbers and INSD accession numbers are given in Table 1. The values of p-distance between the two populations were less than 0.02 and 0.1 for the CO1 and 16S

genes, respectively ( Table 2).

REDESCRIPTION. Length (without antennae) of largest available specimens 2.0–3.3

mm [not given in Kinoshita (1916)]. Body wide, 0.8–1.3 mm in the widest area in region of

Abd.2–3 (length: width = 2.5–3.0), Abd.6 small, but clearly visible from above, Abd.5 with rounded posterior edge. Dorsal side uniformly deep grey-blue in colour ( Figs 1–2 ), ventral side in contrast to dorsum almost colourless. Ground colour slightly yellowish in alive specimens and white in alcohol (at least in the Mt. Takao population). Hypodermic blue pigment intense, covering entire dorsal side of body from antennae to Abd.6, apart from foveae and intersegmental borders, scarce pigmented spots also present on ventral side and legs.

Tegumental granulations uniform and not especially strong.

Antennae about as long as head diagonal or slightly longer, ratio as 1.0–1.2: 1 [isometric after Kinoshita], Ant .3–4 usually longer than Ant .1–2 taking together, ratio as 1.1–1.4: 1.

Ant .3–4 fused dorsally, ventral separation well marked. Ant .4 with a trilobed apical vesicle,

external ms, subapical or and seta i present; dorsal sensilla rather thin, not clearly differentiated from other dorsal setae of Ant .4 (Fig. 15), their number unstable; ventral side of Ant .4

with a well-developed ventral sensorial field consisting of about 100 short, pointed, truncate or slightly clavate microsetae (Fig. 16). Inner sensilla of AO together with dorsal guard (sgd)

moved to middle part of Ant .4, inner sensilla partly covered with a cuticular fold; ventral guard

(sgv) with ms in usual position in proximal part of Ant .3–4. Ant .1 and Ant .2 with 11–12 and

13–14 setae, respectively, setae on dorsal side being shorter than ventral or lateral ones.

(N424) from the type locality (Mt. Takao); 2 – specimens under bark of Abies tree (Chino);

3 – type specimen (slide); 4 – general appearance after Uchida (1965, reproduced with a permission from the Hokuryu-kan, unauthorized copying prohibited); 5 – alive specimen

(N322) from the type locality (Mt. Hikosan), dorsal view; 6 – the same, ventral view.

Head with 8+8 subequal ocelli. PAO narrowly elliptical consisting of 20–25 densely packed vesicles, located in deep rim (Fig. 17). Buccal cone elongate. Maxilla styliform with two tiny apical teeth (Fig. 14), lamellae not clearly seen. Mandible delicate, with one large basal and two smaller apical teeth (Fig. 13). Distal edge of labrum rounded with four tiny papillae, number of labral setae as follows: 4/2-3-3-4 (Fig. 19). Main part of labium with four proximal ordinary setae and distal seta L on tiny papilla, labial organites invisible;

submentum with a usual set of four setae (E, F, G, and f in an unusual position), lateral part of labium (mentum) with (5)6 setae (Fig. 18). Perilabial area with 5 setae on each side. Head with 2+2 long setae along ventral line.

Dorsal chaetotaxy as in Figs 11–12 : tergal sensilla 4–6 times longer than ordinary microsetae; their number per half tergum as follows: 22/21111. Lateral ms on Th.2 present.

Microsetae numerous, forming two irregular lines on most terga, excluding Th.1 ( Fig. 11 ).

Dorsal side of head also with numerous tiny setae, two setae located laterally to ocellus B and

PAO clearly longer.

Thoracic sterna without setae. VT in all available specimens with 3+3 setae (two anterior and one posterior on each side). Ventral abdominal setae much longer than dorsal ones, clearly differentiated and also rather numerous. Main characteristics: sternum of Abd.1 usually with

1+1 setae, Abds.2 with 2–4 (usually 3) ventral setae on each side, number of ventral setae on

Abds.3–4 high and unstable (Fig. 21). Each anal valve with two setae hr. Tenaculum with

3+3 teeth. Furca rather long, almost reaching VT. Manubrium with 8+8 setae on main part, 8–9

setae around macroseta on each basolateral lobe and four basal setae in line (Fig. 21). Dorsal side of dens with six setae and uniform granulation. Mucro long and straight, about half of dens,

tip slightly upturned, lateral lamellae long and subequal, basal part on dorsal side granulated

(Fig. 21), ventral side with a keel reaching tip (as in Fig. 35 ).

Upper subcoxae of all legs covered with tiny and numerous setae similar to dorsal ones,

other parts of legs with usual number of longer setae. Legs 1–3 with 0, 2, (1)2 setae on lower subcoxae, 3, 6–8, 8 setae on coxae, 6, 6, 6 on trochanters, 13, 12, 11–12 setae on femora and

19, 19, 18 setae on tibiotarsi, respectively. Unguis with a strong tooth in lower third of inner edge, a subapical pair of lateral teeth also present, one of them usually being larger.

Empodial appendage absent.

REMARKS. All specimens studied are immature with only a trace of the genital orifice on the sternum of Abd. 5 (Fig. 20), and at least some of quantitative details given above should be taken with caution.

Ceratrimeria takaoensis is rather similar to C. yasumatsui (see redescription below), the second known Japanese species of the genus. Apart from the different colour pattern

(uniform in C. takaoensis vs several large bright spots on dark background in C. yasumatsui ,

cf. Fig. 1 & Fig. 5 ), the two species differ in the number of basal teeth on the mandible (one

vs two in C. yasumatsui ) and the relative lengths of dorsal setae and sensilla (setae in C.

takaoensis are slightly longer, but the sensilla are shorter, their ratio as length of sensilla:

microsetae = 4–6: 1 in C. takaoensis vs 10–12: 1 in C. yasumatsui ). There are also rather distinct differences in antennal structures: a lesser number of dorsal sensilla, as well as short sensilliform setae in ventral file on Ant . 4 in C. takaoensis (cf. Figs 23–25 & Figs 15–16). The number of setae on Ant . 2 in C. takaoensis is usually likewise lesser: 13–14 vs 14–15 (up to

19) in C. yasumatsui , but this character is probably age/size dependent.

DISTRIBUTION AND ECOLOGY. A characteristic corticicolous species living under the bark on dead trunks ( Fig. 2 ) and also in rotten wood which is still known from only two habitats located in the central part of the island of Honshu (Tokyo and Nagano prefectures).

12). Scales: Fig. 7 – 1 mm, 8–12 – 0.1 mm.

Figures

Figs 1–6. Ceratrimeria takaoensis (1–2) and C. yasumatsui (3–6): 1 – alive specimens

Figs 7–12. Dorsal chaetotaxy of Ceratrimeria yasumatsui (7–10) and C. takaoensis (11–

Figs 23–35. Ceratrimeria yasumatsui: 23 – Ant.3–4, dorsal side; 24 – tip of Ant.4; 25 – Ant.3–4, ventral view; 26 – inner sensilla of AO covered by cuticular fold; 27 – PAO and