Australentulus westraliensis ( Womersley, 1932 )

Shrubovych, Julia & D’Haese, Cyrille, 2024, Phylogeny of Australian Acerentomidae species (Protura: Acerentomidae), with a key to identification, Zootaxa 5453 (1), pp. 86-104 : 87-91

Australentulus westraliensis ( Womersley, 1932)

( Figs. 1–20 ; Table 1 )

Acerentulus westraliensis Womersley, 1932: 71

Material examined

Two males. New locality: Margaret River, Bramley National Park, Western Australia, Australia N33.93357°, E115.06883°, 49 m elev. Sifter + Berlèse of leaf litter under a log, 14.XI.2013, coll. C. D’Haese.

Additional description. Head with short setae, cephalic setae l3, sd4 and sd5 setiform and short, seta d6 present, length ratio of posterior setae d7: sd7 as 1.0:1.7 ( Fig. 1 ). Pseudoculus circular, with short posterior extension, PR = 14 ( Fig. 2 ). Maxillary palps apically with a tuft of setae and four single setae, two basal sensilla slender, equal in length ( Fig. 3 ). Labial palps reduced to three setae and sausage-shaped basal sensillum ( Fig. 4 ). Maxillary gland with small, elongated, weakly granulated calyx, long posterior filament and trilobed posterior dilation, CF = 4.5 ( Fig. 5 ).

Foretarsus with sensillum b’, t1 claviform, t3 small and elongated, not leaf-like ( Fig. 6 ); a’ broad and sword-shaped, a broadened, other sensilla slender and parallel-sided. Sensillum a extending past base of t2. Sensillum b shorter than c, reaching base of sensillum e. Sensillum c reaching base of sensillum f. Sensilla b and c inserted in same level, sensillum d inserted between sensilla c and t2. Sensillum a’ extending past base of b’. Sensillum b’ extending past base of sensillum c’, and apex of sensillum c’ extending past the base of claw (see Tuxen 1961: p. 96, Figs. 70-71 ). Length formula of sensilla: t3 <t1 <e <(f = g) <a’ <b’ <(a = c’) <(b = d) <t2 <c. Setae β1 and δ4 slender, setiform, slightly shorter than other δ- setae (β1 and δ4 4 μm, seta δ1 6 μm). Pores on foretarsus near base of sensillum t3 and between bases of sensilla a and c. Claw short, without inner tooth, empodial appendage short. BS = 0.5, TR = 3.5, EU = 0.12.

Chaetotaxy formula is given in Table 1 . Setae on nota strongly differing in length. Pronotal setae 1:2= 1.0:1.5, seta 1a short and setiform, their length 17 μm, 11 μm and 3 μm, respectively ( Fig. 7 ). Meso- and metanotal setae P1a and P2a very short, oblong ( Fig. 8 ), P2a situated very close to P3, seta P5 gemmate ( Figs 7, 9 ). Length ratio of mesonotal setae P1: P2 = 1.0:1.5. Seta P4 on metanotum long and not modified ( Fig. 9 ). Mesonotum with sl and al pores ( Fig. 7 ), metanotum with sl pore only ( Fig. 9 ). Pro-, meso- and metasterna without pores. Setae A2 and M2 on prosternum and seta A2 on thoracic sterna short and setiform, 3 μm in length ( Figs. 12, 13 ).

Accessory setae P1a, P2a and P4a on abdominal tergites I– VII setiform and short, their lengths 4 μm ( Figs. 15‒17 ). Seta P3 on abdominal tergites II– VI inserted anteriorly to other setae of P -row ( Fig. 16 ), P3 on abdominal tergites I and VII on the same level with other setae of P -row ( Figs. 15, 17 ). Tergite VII with a connecting line in anterior part ( Fig. 17 ). Pores psm present on abdominal tergites I– VII between setae P1 and P2, and close to seta P1a on abdominal tergite VII, al pores on abdominal tergites II– VII, psl on tergite VII ( Figs. 15‒17 ). On tergite VII, lt pores present ( Fig. 17 ).

Abdominal legs with 4, 3, 3 setae. Subapical seta on second and third pairs of abdominal legs longer than two apical setae, the length of subapical seta 15 μm, apical medial 6 μm and apical lateral 9 μm ( Fig. 18 ). Accessory setae P1a on sternites I– VII setiform and short (3 μm) ( Figs. 18-20 ). Sternites I– IV without pores. Sternites V – VI with a pair of spsm pores, situated close to bases of setae P1a ( Fig. 19 ), sternite VII with asymmetrical spsm pore ( Fig. 20 ).

Abdominal segment VIII with well-developed striate band (visible parallel-sided striae), with hook-shaped design ( Fig. 14 ). Pore psm with several accompanying teeth. Posterior margin of abdominal sternite VIII and laterotergites smooth. Comb on abdominal tergite VIII with 5 long teeth ( Fig. 11 ). Abdominal sternites IX–XII with smooth hind margin and with different in length setae, medial setae a twice shorter, than lateral ones. Medial pore on dorsal lobe of segment XII and pair of sternal anterolateral pores present.

Male squama genitalis with 4+4 setae ( Fig. 10 ).

Body measurement (2 males) (in μm): body length 850; head 98; pseudoculus 7; posterior part of maxillary gland 22; head setae d7 7, sd7 12; pronotal setae 1 17, 1a 3, 2 11, mesonotal setae P1 10–14, P1a 1, P2 22; foretarsus 63, claw 18, empodial appendage 2.

Remarks. The morphological peculiarities of Au. westraliensis were described on the basis of specimens collected in a new locality located close to the type locality in Western Australia. In this description we added morphological characters which were not analyzed and described earlier, but were added later to the original description and redescriptions ( Womersley 1932, 1939; Tuxen 1961, 1967). These characters concern the shape of maxillary and labial palps, male squama genitalis, chaetotaxy of head, pronotum and thoracic sterna, length and shape of body setae, and porotaxy and lineation of abdominal tergites and sternites. The species is characterized by the presence of additional seta d6 on head, presence of additional seta 1a on pronotum, presence of seta P1a on abdominal tergites I–VI, short foretarsal sensillum a reaching to the base of sensillum t2, long sensillum b surpassing the base of seta γ3, broadened sensillum a’, and shape of comb with 5 long teeth. It is similar to Au. noseki Tuxen, 1967 , Au. occidentale ( Womersley 1932) and Au. victoriae Tuxen, 1967 by possession of P1a on abdominal tergites I–VI. Australentulus westraliensis differs from them all in having only 5 teeth on the comb, whereas other species have 9‒15 teeth. Additionally, the species differs from Au. noseki and Au. occidentale in the short sensillum a reaching the base of sensillum t2 and longer sensillum b surpassing the base of seta γ3. Sensillum a is longer and reaches the base of seta γ3 and sensillum b is shorter and reaches the base of seta γ3. Additionally, the species differs from Au. victoriae in the presence of seta A1 on tergite VII, which is absent in Au. victoriae .

The presence of additional 1a setae on pronotum is known only in Callientomon sinensis Yin, 1980 from China ( Yin 1980; Shrubovych 2014), which belongs to another subfamily, Nipponentominae Yin, 1983 ( Shrubovych et al. 2014a) and in a few protentomids belonging to the genera Condeellum Tuxen, 1963 , Neocondeellum Tuxen & Yin, 1982 and Protentomon Ewing, 1921 (Shrubovych 2014). Australentulus westraliensis also possesses additional pores on the anterolateral part of tergite VII, (laterotergal pores sensu Szeptycki 1993) as in some Gracilentulus species ( Szeptycki 1993). Porotaxy of other Australentulus species is not yet known.

Figures

FIGURES 1–14. Australentulus westraliensis (Womersley, 1932). 1) Hind margin of head. 2) Pseudoculus with setae l3 and sd4. 3) Sensilla on maxillary palp (d = dorsal, l = lateral sensillum). 4) Labial palp (s = sensillum). 5) Maxillary gland. 6) Foretarsal seta t3. 7) Pronotum and mesonotum, right side. 8) Seta P1a on mesonotum. 9) Lateral part of metanotum. 10) Male squama genitalis. 11) Comb. 12) Anterior part of prosternum. 13) Anterior part of mesosternum. 14) Part of striate band.Arrows indicate pores on abdominal tergites (sl = sublateral, al = anterolateral). Scale bars: 20 µm.

FIGURES 15–20. Australentulus westraliensis (Womersley, 1932). 15) Abdominal tergite I, right side. 16) Abdominal tergite VI, right part. 17) Abdominal tergite VII, right part. 18) Part of sternite I. 19) Abdominal sternite VI. 20) Abdominal sternite VII. Arrows indicate pores on abdominal tergites and sternites (al = anterolateral, psm = posterosubmedial, lt = lateral tergal, spsm = sternal posterosubmedial). Scale bars: 20 µm.

FIGURES 63–80. Tasmanentulus tasmanicus (Tuxen, 1967). 63) Pseudoculus with setae l3 and sd4. 64) Cephalic seta sd5. 65) Hind margin of head. 66) Foretarsal sensillum t1. 67) Foretarsal sensillum t3. 68) Mesonotal seta P1a. 69) Lateral part of mesonotum. 70) Lateral part of metanotum. 71) Anterior part of prosternum. 72) Anterior part of mesosternum. 73) Abdominal tergite VII, left part. 74) Abdominal sternite I. 75) Abdominal sternite III. 76) Abdominal leg of sternite III. 77) Hind margin of abdominal sternite VI. 78) Hind margin of abdominal sternite VII. 79) Sternite VIII. 80) Striate band of tergite VIII. Arrows indicate pores on abdominal tergites and sternites (al = anterolateral, sl = sublateral, psm = posterosubmedial, psl = posterosublateral, sc = sternal central, spsm = sternal posterosubmedial, spm = sternal posteromedial). Scale bars: 20 µm.