Podolinella ruseki (Nosek, 1967), n. comb.

Figures 23‒39, Tables 3, 4

Acerentulus ruseki Nosek, 1967:78; 1973:197

Material examined. Holotype female from a Pinus nigra plantation in Frauenstein bei Mödling, Austria, July 1960, coll. G. Haybach. Paratype specimens no longer available.

Other examined material: 2 males, 17 females, 2 pre-imagos, 3 maturus juniors and 3 larvae II from a traditional vineyard in Vernazza (Cinque Terre National Park), 44.136085° N, 9.686286° E, northwestern Italy, 25 February 2014, coll. G. Lionetti; 1 male, 1 female from an holm oak wood near Rio Loaga (Lerca, Genoa Province) 15 November 1995, coll. G. Gardini. These specimens deposited in the collection of Dipartimento di Scienze della Terra, dell’Ambiente e della Vita (DISTAV) of the Genoa University.

Redescription. Body length 1024 ± 32 µm (range: 963–1097; n = 19). Head 109 ± 5 µm long in dorsal view (range 94–116; n = 19); head setae short; setae sd4 and sd5 present, seta d6 absent (Fig. 23). Single frontal pore anterior to the level of the pseudoculi. Rostrum very short. Pseudoculus almost circular, diameter 7 µm (range: 6‒8; n = 19), longitudinally divided (Fig. 24); PR = 15.3 (range 13.1–18.3, n = 19). Maxillary gland with a globular calyx and a distinct “sock-shaped” posterior dilation (Fig. 25), the proximal part 20 µm long (range: 19–22; n = 19), CF = 5.4 (range: 4.8–6.0; n = 19). Maxillary palpus with thin, pointed sensilla (Fig. 26). Labial palpus with three setae and large ovoid sensillum (Fig. 27). Foretarsus length 66 µm (range: 63–68; n = 19), claw 21 µm (range: 18–23; n = 16), without inner tooth, TR = 3.2 (range 2.7–3.6; n = 16); empodium length 6 µm (range: 5–7, n = 16), EU = 0.28 (range 0.24–0.38, n = 16); S-shaped seta as long as claw, 21 µm (range: 20–23; n = 16). Sensillum t1 claviform, BS = 0.48 (range 0.41–0.51, n = 19); t2 thin, t3 large, leaf-like, subequal in length to t1. Sensillum a short, not reaching base of d; sensillum b broad and very long, surpassing the base of claw; c reaching the base of d; sensilla e, f and g reaching the empodium, f nearer to e than to g. Sensillum a’ broad, sword shaped, reaching the base of b’; c' rather long and thin, its apex reaching the base of claw. Ventral seta β 1 slightly shorter than interior seta δ 4; δ 4 situated nearer to c’ than to b’ (Figs. 28–29). Foretarsal pore present near the base of sensillum c (Fig. 28). Middle tarsus length 26 µm (range: 22–28; n = 16); claw length 15 µm (range: 13–16; n = 15). Hind tarsus length 30 µm (range: 27–33; n = 15); claw length 16 µm (range: 13–18; n = 15).

Thoracic tergite I (Fig. 30) with two pairs of setae (ratio setae 1: 2 = 1.54:1; range 1.33‒1.75; n = 19) (Table 3). Thoracic tergites II and III (Fig. 30) each with two pairs of anterior setae (A2, A4); seta P1a very short; seta P2a short, present on mesonotum, nearer to P3 than to P2, absent on metanotum. Seta P5 very short. Length ratio of setae P1: P2 on mesonotum as 1:1.5 (range 1.3–1.6, n = 19). Tergite I with three pairs of anterior setae (A1, A2, A5); seta A5 very short; seta P3 short; setae P1a, P3a, P4a and P5 absent. Tergites II–V each with three pairs of anterior setae (A1, A2, A5); setae P1a and P3a absent (Table 3). Seta A4 present on tergite VI. Seta P 3 in urotergites II‒VI anterior to line P2‒P4. Tergite VII (Fig. 31) with 3 pairs of anterior setae (A2, A4, A5); P3a present. Tergite VIII (Fig. 32) with 3 pairs of anterior setae (A2, A4, A5); P1a absent. Setae P2a on tergites V‒VII very short, close to P2. Tergites IX and X with 12 setae; tergites XI and XII with 4 and 9 setae, respectively (Fig. 32). Prosternum (Fig. 33) formula 2 + 4 / 6 (A1 + M1, 2 / P1, P2, P3), mesosternum and metasternum (Fig. 34) formulas 5 + 2 / 4 and 7 + 2 /4, respectively. Sternites I–VII with 3 anterior setae (Fig. 35); sternites VIII‒XI with 4 setae; sternite XII typically with 6 setae (Fig. 36).

Thoracic tergites II and III with sl pores (Table 4). Tergites I‒VIII with psm pores; al pores on tergites II‒VII; psl pores on tergites VI‒VII (Fig. 31). Tergite XII with ac pore (Fig. 32). Thoracic sternites and abdominal sternites I‒IV without pores. Sternites V‒VII each with asymmetrical spsm pore near the base of seta P1; sal pores on sternites V and VI (Fig. 35); sternite XII with sal pores (Fig. 36).

Connecting lines on anterolateral corners of sternites IV–VI absent. Abdominal appendages II and III with long subapical seta and very short apical median seta. Striate band on Abd. VIII complete, with distinct striae (Figs. 32, 36); comb with 9–12 small and nearly regular teeth (Fig. 37). Irregular row of minute granules just posterior to striate band. Penis with 5 + 5 setae (Fig. 38). Female squama genitalis distinctly tripartite with pointed acrostylus (Fig. 39).

Chaetotaxic variation infrequent; symmetrical and asymmetrical absence of seta P2a on thoracic tergite II (one adult in both cases); asymmetrical absence of seta A4 on tergite VI (one adult); asymmetrical absence of seta A1 on tergite V (one adult); symmetrical and asymmetrical absence of seta 1 on tergite IX (one adult in both cases); asymmetrical presence of a long seta between P2 and P3 on sternite VI (one adult); presence of only 3 setae on sternite IX. On holotype seta P2a on metanotum nearer to seta P3 than to P2.

Imago and Pre-imago Maturus Junior Larva II

Formula Complementary Setae Formula Complementary Setae

Dorsal

*Seta P2a present only in the holotype.

Pre-imago. Length of body 889, 895 µm (n = 2), head 97, 100 µm, foretarsus length 62, 64 µm, TR = 3.4, 3.5, BS = 0.48, 0.52. Chaetotaxy and porotaxy identical to those of adults (Tables 3, 4).

Maturus junior. Length of body 752 ± 17 µm (range: 742–771; n = 3), head 90 ± 6 µm (range: 84–96; n = 3), foretarsus length 55 ± 4 µm (range: 52–60; n = 3), TR = 3.3, BS = 0.51‒0.57. Chaetotaxy (Table 3) differing from that of adults in absence of seta A4 on tergite VI, absence of setae 1a and 2a on tergite X, absence of setae on sternite XI.

Larva II. Length of body 666 ± 21 µm (range: 643–683; n = 3), head 80 ± 6 µm (range: 73–83; n = 3), foretarsus length 48 ± 1.5 µm (range: 47–50; n = 3), TR = 2.8–3.6. Chaetotaxy is shown in Table I.

Distribution. Previously known only from the type locality in Austria. The new material was collected in two different localities from Liguria, northwestern Italy, and represents the first record of the species and genus in the Italian fauna.

Diagnosis and discussion. Podolinella ruseki n. comb. has a number of characters in common with other genera of Acerentomidae in subfamily Berberentulinae, especially Gracilentulus Tuxen, 1963, Podolinella Szeptycki, 1995, Tuxenidia Nosek & Cvijović, 1969 and Vindobonella Szeptycki & Christian, 2001. These characters include the mesonotum and metanotum with 4 anterior setae (A2 and A4), sternites I‒VII with three anterior setae, seta P 3 in urotergites II‒VI anterior to line P2‒P4, abdominal legs II and III with two setae, striate band on abdominal segment VIII complete, labial palp without tuft, seta P2a on mesonotum and metanotum (if present) nearer to P3 than to P2, maxillary gland with large, nearly semiglobular calyx and foretarsus with sensillum b’. It differs from all the genera above in the shape of the labial palp sensillum (ovoid) and in the position of sensillum d on foretarsus (rather distal, nearer to e than to c), but seems to have more affinities with Podolinella and Gracilentulus. It shares with Gracilentulus the presence of a post-pseudocular seta (sd4), but Gracilentulus has A2 setae on thoracic sternite I and typically a short knob-like foretarsal sensillum t3 (G. sarmaticus Shrubovych & Szeptycki, 2008 has a large t3 subequal in length to t1). It also shares with G. sarmaticus a long sensillum b. We place A. ruseki in genus Podolinella, with which it shares the presence of only two setae on abdominal appendages, the shape and relative length of maxillary gland, the shape and length of foretarsal sensillum b, the sensilliform and leaf-like shape of foretarsal sensilla t2 and t3 respectively, the absence of seta A2 on thoracic sternite I and the developed striate band with distinct parallel-sided striae. Podolinella podolica shares with P. ruseki the absence of seta d6 on the head, but lacks sd4 seta, has shorter main setae on the nota and differs from P. ruseki for chaetotaxy of tergites VII‒VIII and sternites II‒III.