Amphientulus markstivensi, Shrubovych & D’Haese, 2024

Shrubovych, Julia & D’Haese, Cyrille, 2024, Phylogeny of Australian Acerentomidae species (Protura: Acerentomidae), with a key to identification, Zootaxa 5453 (1), pp. 86-104 : 91-96

Amphientulus markstivensi sp. nov.

( Figs. 21–44 , 45–62 ; Table 2 )

Material examined

Holotype: female ( ISEA 6652 ): Australia, Tasmania, Derwent Bridge Cradle Mountain, Lake St Clair National Park, Shadow Lake track to Mount Rufus track, Berlese of buton grass litter, N42.10393°, E 146.12159°, 946 m elev., 31.III.2015, collected by C. D’Haese. Paratypes 2 females ( ISEA 6653 , 6654 ), the same data as holotype . Other materials: 2 maturi juniores and 1 Larva I, the same data as holotype .

Description. Body long and slender ( Fig. 45 ). Head with short setae, cephalic setae l3, sd4 and sd5 short and setiform ( Figs. 21, 22 , 46–48 ), seta d6 absent ( Fig. 46 ), length ratio of posterior setae d7: sd7 as 1.0:1.5. Pseudoculus circular, with short posterior extension, PR = 14 ( Fig. 21 ). Maxillary palps apically with a tuft of setae, four single setae and two basal sensilla slender and equal in length ( Figs. 23 , 49 ). Labial palps reduced to four setae and broad basal sensillum ( Figs. 24 , 50 ). Maxillary gland with small elongated and weakly granulated calyx, long posterior filament and bilobed posterior dilation, CF = 6.4 ( Fig. 25 ).

Foretarsus with sensillum b’, t1 claviform, t3 small and jar-shaped ( Figs. 27–29 , 51–53 ); a’ broadened and sword-shaped, other sensilla slender and parallel-sided. Sensillum a extending past base of t2. Sensillum b shorter than c, reaching base of seta γ3. Sensillum c almost reaching base of sensillum f. Sensilla b and c inserted at same level, sensillum d inserted between sensilla c and t2, close to base of sensillum c. Sensillum a’ extending past base of b’. Sensillum b’ extending past base of sensillum c’, apex of sensillum c’ extending past the base of claw. Length formula of sensilla: t3 <t1 <g <(b = a’) <(a = d) <(f = b’) <(e = t2) <c’. Setae β1 and δ4 setiform, slightly broader than but same length as other δ- setae (8 μm). Pores on foretarsus near base of sensillum t3 and near base of seta α3 between bases of sensilla a and c. Claw short, without inner tooth, empodial appendage short. BS = 0.3, TR = 3.1, EU = 0.1.

Formula of the chaetotaxy given in Table 2 . Setae on nota strongly differing in length. Pronotal setae 1:2 = 1.0:2.0 ( Figs. 31 , 54 ). Mesonotal setae P1a and P2a very short (2 μm), oblong ( Figs. 31 , 55 ), metanotal setae P1a and P2a twice as long (4 μm), oblong ( Fig. 32 ). Seta P2a on meso- and metanota situated very close to P3, seta P3a setiform and four times longer than P1a and P2a ( Fig. 56 ), seta P4 setiform and long, seta P5 gemmate ( Figs. 31, 32 ). Length ratio of mesonotal setae P1: P2 = 1.0:1.5 ( Fig. 31 ). Mesonotum with sl and al pores ( Figs. 31 , 55 ), metanotum with sl pore only ( Fig. 32 ). Pro- and mesosterna without pores; metasternum with one or two closely placed sc pores ( Fig. 39 ). Setae A2 and M2 on prosternum and seta A2 on thoracic sterna short, setiform, their length 6 μm ( Figs. 37–39 ).

Accessory setae P2a and P4a on abdominal tergites I–VI setiform and short, their lengths 4 μm ( Figs. 33, 34 ). Accessory setae P1a, P2a and P4a on tergite VII setiform, their lengths 7 μm ( Figs. 35 , 57 ). Seta P3 on abdominal tergites II–VI inserted anteriorly to other setae of P -row ( Figs. 34 , 58 ), P3 on tergites I and VII on the same level with other setae of P -row ( Figs. 33, 35 ). Abdominal tergite VII anteriorly with two cuticular lines crossed in medial part of tergite ( Fig. 35 ). Pores psm present on abdominal tergites I–VII between setae P1 and P2, and close to seta P1a on tergite VII ( Fig. 57 ), al pores on tergites II–VII, psl on tergite VII ( Figs. 33–35 ).

Abdominal legs with 4, 2, 2 setae. Subapical seta on second and third pairs of abdominal legs longer than apical lateral seta, the length of subapical seta 23 μm and apical lateral 14 μm ( Figs. 41 , 59 ). Accessory setae P1a on abdominal sternites II–VII setiform and longer, than on abdominal tergites I–VII (9 μm) ( Figs. 41–43 , 60 ). Abdominal sternite VI with a connecting cuticular line ( Fig. 42 ), sternite VII with two parallel connecting lines ( Fig. 43 ). Sternites I–IV without pores ( Figs. 40, 41 ). Abdominal sternites V–VI with a pair of spsm pores, situated between bases of setae P1a and P2 ( Fig. 42 ), sternite VII with spm pore ( Fig. 43 ).

Abdominal segment VIII with striate band reduced to two lines and without parallel-sided striae, but with hook-shaped design (a few oblique, sinuate striae) ( Figs. 36, 44 , 57, 61 ). Pore psm with several accompanying teeth ( Fig. 36 ). Posterior margin of abdominal sternite VIII and laterotergites smooth ( Fig. 44 ). Comb on tergite VIII with 9–10 short teeth ( Figs. 30 , 62 ). Abdominal sternites IX–XII with smooth hind margin and with setae of different lengths, medial setae half the length of lateral ones ( Fig. 44 ). Medial pore on dorsal lobe of segment XII, one pair of sternal anterolateral pores.

Female squama genitalis with short, forked acrostyli ( Fig. 26 ).

Body measurements (3 females) (in μm): body length 1150; head 135–140; pseudoculus 6; lever 2–3; posterior part of maxillary gland 22; head setae d7 15, sd7 10, l5 6; pronotal setae 1 28, 2 13–14, mesonotal setae P1 21, P1a 2, P2 30–31; metanotal setae P1a 4; foretarsus 80, claw 26, empodial appendage 2.

Remarks. The species is characterized by the absence of P1a setae on abdominal tergites I–VI and P3a on tergite VII, presence of P4a setae on tergites II–VI, sensilliform shape of accessory setae on abdominal segments and two P setae on abdominal sternite I. Two paratypes (ISEA 6653, 6654) have A1 setae on abdominal tergite VII and posterior setae on abdominal sternite VIII, but the asymmetrical presence of these setae suggests a direction toward reduction of these setae in speciation.

All Tasmanentulus species ( T. tasmanicus , T. similis , T. intermedius ) are characterized by possession of setae P1a on abdominal tergites I–VI, setiform shape of accessory setae on the abdominal segments, 6 setae on abdominal sternite VIII and long foretarsal sensillum t3 with cylindrical shape ( Tuxen 1984, 1986). Therefore, we place the species in Amphientulus due to the absence of P1a setae on abdominal tergites I–VI, sensilliform accessory setae on abdominal segments, jar-shaped foretarsal sensillum t3 and completely reduced striate band to two lines without any trace of striae.

Figures

FIGURES 21–30. Amphientulus markstivensi sp. nov., holotype (ISEA 6652). 21) Pseudoculus with setae l3 and sd4. 22) Cephalic seta sd5. 23) Maxillary palp. 24) Labial palp. 25) Maxillary gland. 26) Female squama genitalis. 27) Foretarsus, exterior view. 28) Foretarsus, interior view. 29) Foretarsal sensillum t3. 30) Comb. Arrows indicate pores. Scale bars: 20 µm.

FIGURES 31–44. Amphientulus markstivensi sp. nov. holotype (ISEA 6652). 31) Pronotum and mesonotum, right side. 32) Lateral part of metanotum. 33) Tergite I, right side. 34) Tergite VI, right part. 35) Abdominal tergite VII, right part. 36) Abdominal tergite VIII, right part. 37) Anterior part of prosternum. 38) Antero-lateral part of mesosternum. 39) Anterolateral part of metasternum. 40) Part of abdominal sternite I. 41) Abdominal sternite III with abdominal leg. 42) Abdominal sternite VI. 43) Abdominal sternite VII. 44) Abdominal sternites VIII–X. 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.

FIGURES 45–50. Amphientulus markstivensi sp. nov. 45) Habitus. 46) Head. 47) Pseudoculus with setae l3 and sd4 (fp = frontal pore). 48) Cephalic seta sd5. 49) Maxillary palp (d = dorsal sensillum, l = lateral sensillum). 50) Labial palp (s = sensillum).

FIGURES 51–56. Amphientulus markstivensi sp. nov. 51) Foretarsal sensilla a, b, c, t2 and t3. 52) Foretarsal sensilla a’, b’,c’ and t3. 53) Foretarsal sensillum t1. 54) Pronotal setae 1 and 2, mesonotal al and sl pores. 55) Mesonotal seta P1a. 56) Setae P2a and P3a on metanotum.

FIGURES 57–62. Amphientulus markstivensi sp. nov. 57) Setae P1a and P2a on abdominal tergite VII (arrow indicates pore psm) and striate band on abdominal tergite VIII. 58) Position of seta P3 on abdominal tergites VI and VII. 59) Second and third pairs of abdominal legs. 60) Seta P1a on abdominal sternite VII. 61) Striate band on abdominal sternite VIII. 62) Comb on abdominal tergite VIII.