Entomobrya handschini Stach, 1922

Winkler, Daniel, Sternalski, Jakub, Onodi, Gabor, Szigeti, Nora, Florian, Norbert & Danyi, Laszlo, 2023, Investigation on the true identity of Entomobrya nigriventris Stach, 1929 (Collembola, Entomobryidae) with the description of a new species, ZooKeys 1185, pp. 321-353 : 321

Entomobrya handschini Stach, 1922

Figs 10 , 11

Material.

Five ♂♂ and five ♀♀ on three slides (Nr. HNHM-collpr-919 to HNHM-collpr-920; and WD-coll-149), 17 specimens in 96% ethyl alcohol (Vial WD179). Hungary, Osli , com. Győr-Moson-Sopron, 112 m asl, 47°39'05"N, 17°06'15"E, D-vac sample, 12 Jul. 2020, leg. D. Winkler. Two slides are stored at HNHM, one slide and the specimens in alcohol are preserved at SOE .

Description.

Habitus. Adult body length up to 3.62 mm excluding antennae. Base colour pale yellow to orange-brown. Colour pattern typically with five longitudinal stripes running from the anterior part of Th II: the central stripe thin and often reaching the posterior part of Abd IV, the dorsolateral stripes reach the mid Abd II. Irregular oblique patches typical for the species on both Abd II and III. Abd IV with four or five irregular patches separated or connected (Fig. 10A ). Ventral body entirely dark in most of the adult specimens (Fig. 10B )

Head. 8+8 eyes, GH smaller than EF (Fig. 11A ). Interocular chaetotaxy with five chaetae (s, t, p, q, r). Antennae length 1.30-1.99 mm (n = 7). Antennal length to head diagonal length ratio 2.49-3.26 (n = 7). Relation of antennal joints I-IV as 1: 2.2: 1.9: 2.2. Ant IV with bilobed apical bulb. Ant III sensillary organ composed of two sensory rods partially behind a cuticular fold, guarded by three short sensilla. Arrangement of chaetae on labrum 4/554, prelabral chaetae ciliated, posterior, median and anterior labral chaetae smooth. Labrum with four labral papillae with spine-like expansion (as in Fig. 8B ). Outer maxillary palp with two smooth chaetae and three smooth sublobal chaetae. Lateral process on labial papilla E not reaching apex of papilla (as in Fig. 3E ). Labium chaetotaxy formed by 5 smooth “a” chaetae and, in basal row, by ciliated chaetae M, R, E, L1, and L2 with R smaller than other chaetae (ratio of R/M~0.7).

Body. Ratio of Abd IV/III length 3.14-3.89 (n = 9). No differentiated chaetae on tibiotarsus III, except for smooth terminal chaeta opposite to tenent hair. Trochanteral organ with up to 24 spine-like chaetae (Fig. 11B ). Unguis with sub-equal paired basal teeth at 52% from the inner edge and with two more unpaired teeth at 76% and 89% from inner edge, respectively. Unpaired dorsal and paired lateral teeth intermediate, at level slightly below the paired internal teeth. A small pretarsal chaeta present on both anterior and posterior surfaces. Unguiculus lanceolate, outer lamella smooth (Fig. 11C ). Tibiotarsal tenent hair clavate, as long as claw. Ratio of smooth terminal chaeta / unguiculus 0.9. Ventral tube with 17+17 ciliated chaetae on anterior side and 9+9 ciliated chaetae on posterior side; lateral flap with 6 ciliated and 11 smooth chaetae. Manubrial plate with 5-6 chaetae and two psp (Fig. 11D ). Length of not ringed terminal dens ~ 2.5 × the length of mucro. Mucro with apical tooth markedly larger than anteapical; basal spine just reaching tip of anteapical tooth.

Macrochaetotaxy (Fig. 11A, E-H ). The studied population can be described by the following abbreviated formula: 4-1-0-3-2/4-5(6)/2-5(7)/0-2-2/0-10(0)4(5)-10(0)4-10(0)3(5)-2.

Head (Fig. 11A ): H1 area with four Mac (An2, An3a1, An3a2, An3); H2 area with one Mac (A5); H3 area without Mac; H4 area with three Mac (S1, S3, S4i); H5 area with two Mac (Ps2 and Ps5). Mesothorax (Fig. 11E ): area T1 with four Mac (m1, m2, m2i, m2i2); T2 with 5-6 Mac (a5, m4, m4i, m4p, m5 always present, m4pi present or absent). Abdomen: Abd II (Fig. 11F ) area A1 with two Mac (a2 and a3); area A2 with 5-7 Mac (m3, m3e, m3ep, m3ei, m3ea always present, m3eai and m3eai2 present or absent); Abd III (Fig. 11G ) area A3 without Mac; area A4 with two Mac (a2 and a3), and area A5 also with two Mac (m3 and m3e); Abd IV (Fig. 11H ) area A6 without Mac; area A7 with unpaired central Mac A03 present or absent, and with 4-5 Mac (A3, B2, C1, E1 always present; Ae3 present or absent); area A8 with unpaired central Mac A04 present or absent, and with four Mac (A4a, Ae4, B4, C2a); area A9 with unpaired central Mac A05 present or absent, and with 3-5 Mac (A5, B5, and one Mac of uncertain homology always present, Ae5p and Ae5pp present or absent); and area A10 with two Mac (A6 and B6); sensillar formula from Th II to Abd V: 2,2/1,2,2,10,3; microsensillar formula from Th II to Abd III: 1,0/1,0,1.

Ecology.

The specimens were collected in a secondary hay meadow with woody patches.

Remarks.

Baquero et al. (2008) presented a comprehensive redescription of E. handschini , providing a large set of characters (including macrochaetotaxy) from specimens from five different localities (Austria, Crete, Greece, Iran, and Slovakia). Variations in colour pattern are presented in several works, however, neither the original description ( Stach 1922) nor the subsequent redescriptions ( Stach 1963; Baquero et al. 2008; Jordana 2012) mention the possible occurrence of a dark-coloured ventral side, which is presented in this paper for the first time. Further differences compared to previous descriptions include slight variations in the macrochaetotaxy of some areas. There is one more Mac (a total of four) in the area H1 (head). However, this phenomenon is also observed in other Entomobrya species, especially in larger individuals, where the antennal series can include more macrochaetae ( Furgoł 2017). T2 area (Th II) can have one more Mac, while A2 area (Abd II) can bear two more additional Mac than previously reported ( Baquero et al. 2008; Jordana 2012). On Abd IV, the presence of unpaired macrochaetae has not previously been reported, while in the studied specimens, we occasionally detected unpaired chaetae in areas A7, A8, and A9, respectively. The number of Mac in the A9 area can reach up to five, including a Mac of uncertain homology always present in the B row. The same Mac was also indicated by Baquero et al. (2008) as Ae5pp shifted outwards.

The abovementioned differences can be considered as slight variations. Taking them into account, the species E. handschini can be characterised by the following simplified formula: 3(4)-1-0-3-2/4-5(6)/2-5(7)/0-2-2/0-10(0)3(5)-10(0)4-10(0)3(5)-2.

Figures

Figure 3. Entomobrya arenaria sp. nov. A head chaetotaxy B apex of Ant IV C Ant III sensillar organ D labrum with labral papillae, maxillary palp and sublobal plate E labial papilla E with lateral process (l. p.) F labial triangle, arrow indicates M 2 chaeta present or absent. Abbreviations: Ant = antennal segment. Scale bars: 0.05 mm (A); 0.02 mm (B, D); 0.03 mm (C, F); 0.01 mm (E).

Figure 8. Entomobrya nigriventris A head chaetotaxy B labral papillae C trochanteral organ D unguis and unguiculus of leg III E Ventral tube anterior view (left side) and posterior view (right side), circles-ciliated chaetae F Manubrial plate G Th II dorsal macrochaetotaxy H Abd II dorsal macrochaetotaxy I Abd III dorsal macrochaetotaxy J Abd IV dorsal macrochaetotaxy. Abbreviations: Abd = abdominal tergite; Th = thoracic tergite. Scale bars: 0.03 mm (A, D-F); 0.02 mm (B); 0.05 mm (C, G-J).

Figure 10. Entomobrya handschini. Habitus A dorsolateral view B ventral view (same specimen). Scale bars: 1 mm.

Figure 11. Entomobrya handschini A head chaetotaxy B trochanteral organ C unguis and unguiculus of leg III D manubrial plate E Th II dorsal macrochaetotaxy F Abd II dorsal macrochaetotaxy G Abd III dorsal macrochaetotaxy H Abd IV dorsal macrochaetotaxy. Abbreviations: Abd = abdominal tergite; Th = thoracic tergite. Scale bars: 0.03 mm (A, B, D); 0.02 mm (C); 0.05 mm (E-H).