Acerentulus tortii, Galli, Loris, Capurro, Matteo, Lionetti, Giuseppe & Zinni, Matteo, 2017

Galli, Loris, Capurro, Matteo, Lionetti, Giuseppe & Zinni, Matteo, 2017, Acerentulus tortii sp. nov. from Greece (Protura: Acerentomidae), Zootaxa 4232 (3), pp. 437-443 : 437-442

Acerentulus tortii sp. nov.

Figures 1–18 , Tables 1 , 2 Type material. Holotype female from soil collected under Abies cephalonica 650 m a.s.l., near Stropones (38° 36’ N, 23° 54’ E), Euboea Island, Central Greece, 30th April 1987, coll. B. Hauser; 8 male and 30 female paratypes, same locality as holotype.

Other material examined. Five pre-imagos, 4 maturus juniors, 2 larvae II. The holotype and most of the paratypes are deposited in the Geneva Natural History Museum, Switzerland ( MHNG registry number of the series: Ir-87/26). Two paratypes (1 male, 1 female) are deposited in the collection of Dipartimento di Scienze della Terra, dell’Ambiente e della Vita (DISTAV) of Genoa University.

Description. Female and male dimensions significantly different only in body length (Mann-Whitney U = 28, z = -2.0333, p <0.05). Length of females 1200 ± 153 µm (935‒1435, n = 15), length of males 1053 ± 130 µm (869—1290, n = 8).

Head 139 ± 7 µm long in dorsal view (127—161; n = 23). Setae sd4, sd5 and l3 short and thin; seta d6 absent ( Fig. 1 ). Frontal pore fp present, anterior to level of pseudoculi ( Fig. 1 ). Pseudoculus almost circular, diameter 10 ± 1 µm (9—12, n = 24), longitudinally divided ( Fig. 2 ); PR = 13.4 ± 1.1 (11.5—16, n = 23). Proximal part of the maxillary gland canal ( Fig. 3 ) 32 ± 3 µm long (27—37, n = 22), with tripartite posterior dilation, CF = 4.3 ± 0.3 (3.7—4.9, n = 21). Maxillary palpus with two seta-like sensilla ( Fig. 4 ). Labial palpus with apical tuft of setae and long, slender sensillum ( Fig. 5 ).

Foretarsus length 117 ± 4 µm (110—125, n = 23), claw 31 ± 2 µm (28—35, n = 22), without inner tooth or outer flap; TR = 3.9 ± 0.3 (3.4—4.4, n = 22); empodium length 5 ± 1 µm (4—6, n = 18), EU = 0.15 ± 0.02 (0.13—0.18, n = 18); S-shaped seta slightly longer than claw, length 33 ± 2 µm (30—36, n = 8). Sensillum t1 claviform, BS = 0.35 ± 0.02 (0.30—0.39, n = 23); t2 thin, t3 shaped like a willow leaf. Sensillum a passing the base of d; b passing the base of γ3; c shorter than b, just reaching γ3; d short, not reaching e; e slightly passing the base of g; f slightly closer to e than to g, apices of both f and g not reaching the base of claw; f longer than g. Sensillum a' broad and distal to t1, short, not reaching base of b'; b' thin and slightly passing base of c'; c' thin, its apex not reaching base of claw. Ventral seta β1 shorter than interior seta δ4; δ4 situated proximally to c’; δ-setae all rather short ( Figs. 6, 7 ). Foretarsal pore present near sensillum c ( Fig. 6 ). Middle tarsus length 50 ± 3 µm (44—57, n = 21), claw length 21 ± 3 µm (15—26, n = 21). Hind tarsus length 59 ± 3 µm (52—67, n = 21), claw length 22 ± 2 µm (range: 17—26; n = 21). Inner margin of middle and hind tarsus coxae with pointed tooth.

Thoracic tergite I with two pairs of setae ( Table 1 ). Thoracic tergites II–III ( Fig. 8 ) each with two pairs of dorsal anterior setae (A2, A4); setae P2a nearer to P3 than to P2. Seta P5 very short. Length ratio of setae P1: P2 on pronotum 1:2.64 (2.17—3.46, n = 23) on mesonotum 1:1.26 (1.11—1.52, n = 21). Tergite I with three pairs of anterior setae (A1, A2, A5) with seta A5 very 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. Tergites VI–VII ( Fig. 9 ) with 4 pairs of anterior setae (A1, A2, A4, A5); P1a and P3a absent on tergite VI. Tergite VIII with 3 pairs of anterior setae (A2, A4, A5); P1a absent. Tergites IX and X with 12 setae; tergites XI and XII with 6 and 9 setae, respectively ( Fig. 10 ). Prosternum, mesosternum and metasternum formulas typically 4+4/6, 5+2/4 and 7+2/4, respectively ( Figs. 11, 12 ); seta M of meso- and metasternum bordered by lightly granulated area ( Fig. 12 ). Sternites I–VII with 3 anterior setae ( Fig. 13 ); sternite VIII with 4 anterior setae and 2 posterior setae; sternites IX–XI with 4 setae; sternite XII with 6 setae ( Fig. 14 ).

On thoracic tergites II–III sl pores present; al pore present only on tergite II ( Fig. 8 , Table 2 ). Psm pores present on abdominal tergites I—VIII; al on tergites II–VII; psl on VI and VII ( Fig. 9 ). Thoracic sternites and abdominal sternites I—III without pores. Sternites IV and V with spsm pores near the base of P1 ( Fig. 13 ). Sternite VI with two groups of spsm pores (1—3) symmetrically placed anterior to P1. Sternite VII with spm pore near its hind margin, between P1 setae ( Fig. 13 ). Pores in some specimens flanked by 2 or three small teeth ( Fig. 13 ).

Connecting lines on anterolateral corners of sternites IV–VI absent. Abdominal appendages II and III each with three setae ( Fig. 15 ). Granular latero-dorsal area on tergite VI elongated, roughly rectangular ( Fig. 9 ). Striate band on Abd. VIII well developed, with distinct striae ( Figs. 10, 14 ); comb with about 1 0–12 regular teeth ( Fig. 16 ). Nearly continuous row of minute granules just posterior to the striate band ( Figs. 10, 14 ). Male squama genitalis with 5 + 5 setae ( Fig. 17 ). Female squama genitalis with tripartite acrostylus ( Fig. 18 ).

Variability. One adult with asymmetrical presence of long P2a seta on tergite VII.

Pre-imago. Length of body 1002 ± 71 µm (941—1104, n = 4); head length 125 ± 7 µm (118—133, n = 4); foretarsus length 97 ± 4 µm (93—102, n = 5); TR = 3.4 ± 0.2 3.3—3.6, n = 5); BS = 0.36 ± 0.03 (0.32—0.41, n = 5). Chaetotaxy (Table I) and porotaxy (Table II) identical to those of adults.

Maturus junior. Length of body 834 ± 88 µm (744—931, n = 4); head length 117 ± 6 µm (111—125, n = 4); foretarsus length 91 ± 5 µm (85—96; n = 4); TR = 3.6 ± 0.2 (3.4—3.8, n = 4); BS = 0.34 ± 0.01 (0.33—0.35, n = 4). Chaetotaxy (Table I) differing from that of adults in absence of seta A4 on tergite VI; setae 1a and 2a absent on tergite X; seta P2 absent on thoracic sternite I; seta 2 absent on sternite XI.

Larva II. Length of body 517, 596 µm; head length 96, 104 µm; foretarsus length 71 µm; TR = 3.1, 3.6; BS = 0.37, 0.39. Anterior setal rows absent on Abd. I—VII (Table I).

Etymology. This species is dedicated to our friend and master Dr. Carlo Torti.

1 Following Galli & Capurro (2013).

Diagnosis and discussion. Acerentulus tortii sp. nov. belongs to the A. cunhai species group ( Nosek, 1973), members of which have a short foretarsal sensillum a not reaching seta γ3, and sensilla b and c subequal in length. A key to species belonging to this group was given by Shrubovych et al. (2014). In the new species foretarsal sensillum b is slightly longer than c; d and e are short; apices of f, g and c' do not reach the base of the claw; a' is broad, short, not reaching base of b'; b' and c' are thin. The connecting line on sternites IV—VI is absent. Pores are absent on the meso- and metasternum and on sternites I–III; symmetrical groups of spsm pores are present on sternite VI. The female squama genitalis has tripartite acrostylus.

In the key of Shrubovych et al. (2014) A. tortii sp. nov. will trace to A. christensoni (Ewing, 1940) . Acerentulus christensoni has a very long foretarsal sensillum b, much longer than c and reaching seta γ4, and long sensillum f reaching the base of the claw. Acerentulus tortii n. sp. is also quite similar to A. rafalskii Szeptycki, 1979 , which differs from the new species in having foretarsal sensilla b and c subequal (both passing γ3), sensillum d long and reaching f, e long (widely passing g), a’ very short (barely reaching t2), the presence of an asymmetrical spsm pore on sternite III (1 + 0), shorter foretarsus (79–82 µm vs 110–125 µm), comb VIII with 8–9 teeth and male squama genitalis with 6 + 6 setae.

The chaetotaxy of the new species also is similar to that of A. cunhai Condé, 1950 , A. sexspinatus Womersley, 1936 , A. keikoae keikoae Imadaté, 1988 and A. kermadecensis Ramsay & Tuxen, 1978 . This last species differs from A. tortii in having an elongated pseudoculus with an additional structure at the end of the lever, 6 setae on sternite XI, foretarsal sensillum b more proximal than c, and d long, passing base of e. In A. keikoae keikoae setal numbers on sternites VII and XI are 3/9 (Pc present) and 6, respectively, differing from those of the new species; foretarsal sensillum a’ is long and reaches b’; and c’ is long (passing base of claw). A. sexspinatus is bigger than A. tortii n. sp. (body length 1725 µm, head 160 µm, foretarsus 130 µm) and is characterized by a particularly short claw (TR = 6); sternite XI bearing 6 setae; foretarsal sensillum a’ long, passing b’; and c’ long (reaching base of claw). A. cunhai differs from the new species in porotaxy: the meso- and metasternum have an sc pore, sternite I has an asymmetrical spsm pore (1 + 0) and sternite VII bears an asymmetrical pore near P1. The foretarsal sensillum a of A. cunhai is short, barely reaching base of d; d is long, passing f; and the female squama genitalis is bipartite.

Figures

FIGURES 1 – 8. Acerentulus tortii sp. nov. 1) Head, dorsal view. 2) Pseudoculus. 3) Canal of maxillary gland. 4) Maxillary palpus. 5) Labial palpus. 6) Foretarsus, exterior view. 7) Foretarsus, interior view. 8) Pro, meso and metanotum. Arrows indicate pores. Figs. 1 – 5: holotype; Figs. 6 – 8: paratypes.

FIGURES 9 – 18. Acerentulus tortii sp. nov. 9) Tergites V – VII. 10) Tergites VIII – XII. 11) Prosternum. 12) Mesosternum. 13) Sternites V – VII. 14) Sternites VIII – XII. 15) Abdominal appendage II. 16) Comb on abdominal tergite VIII. 17). Male squama genitalis. 18) Female squama genitalis. Arrows indicate pores. Figs. 11 – 13: holotype; Figs. 9, 10, 14 – 18: paratypes.

Tables

TABLE 1. Chaetotaxy of Acerentulus tortii sp. nov.

	Imago and Formula	Pre-imago Setae	Maturus junior	Larva II Formula	Setae
Dorsal
Thorax I	4	1, 2	As adult	4	1, 2
II-III	6/16	A2, 4, M P1, 1a, 2, 2a, 3, 4, 4a, 5	As adult	6/14	A2, 4, M P1, 1a, 2, 3, 4, 4a, 5
Abdomen I	6/10	A1, 2, 5 P1, 2, 2a, 3, 4	As adult	0/10	P1, 2, 2a, 3, 4
II-V	6/14	A1, 2, 5 P1, 2, 2a, 3, 4, 4a, 5	As adult	0/14	P1, 2, 2a, 3, 4, 4a, 5
VI	8/14	A1, 2, 4, 5 P1, 2, 2a, 3, 4, 4a, 5	A4 absent	0/14	P1, 2, 2a, 3, 4, 4a, 5
VII	8/18	A1, 2, 4, 5 P1, 1a, 2, 2a, 3, 3a, 4, 4a, 5	As adult	0/14	P1, 2, 2a, 3, 4, 4a, 5
VIII	6/16	A2, 4, 5 P1, 2, 2a, 3, 3a, 4, 4a, 5	As adult	2/14	A4 P2, 2a, 3, 3a, 4, 4a, 5
IX	12	1, 1a, 2, 2a, 3, 4	As adult	4	1, 2, 3, 4
X	12	1, 1a, 2, 2a, 3, 4	1a and 2a absent	9
XI	6	1, 3, 4	As adult	-
XII	9		As adult	-
Ventral
Thorax I	(4+4)/6	A1, 2, M1, 2 P1, 2, 3	P2 absent	(2+2)/4	A1, M1 P1, 3
II	(5+2)/4	Ac, 2, 3, M P2, 3	As adult	(5+2)/2	Ac, 2, 3, M P2
III	(7+2)/4	Ac, 2, 3, 4, M P2, 3	As adult	(5+2)/2	Ac, 2, 3, M P2
Abdomen I	3/4	Ac, 2 P1, 1a	As adult	3/2	Ac, 2 P1
II-III	3/5	Ac, 2 Pc, 1a, 2	As adult	1/5	Ac Pc, 1a, 2
IV-VII	3/8	Ac, 2 P1, 1a, 2, 3	As adult	1/6	Ac, P1, 2, 3
VIII	4/2	A1, 2 P1a	As adult	4/0	A1, 2
IX	4	1, 2	As adult	4	1, 2
X	4	1, 2	As adult	6
XI	4	1, 2	2 absent	-
XII	6		As adult	-

TABLE 2. Porotaxy of Acerentulus tortii sp. nov.

	Imago
	Formula	Pores
Dorsal
Thorax I	0
II	2 + 2	al, sl
III	1 + 1	sl
Abdomen I	1 + 1	psm
II–V	2 + 2	psm, al
VI–VII	3 + 3	psm, psl, al
VIII	1 + 1	psm
IX–XI	0
XII	1	ac 1
Ventral
Thorax I–III	0
Abdomen I–III	0
IV–V	1 + 1	spsm
VI	n + n	spsm
VII	1	spm
VIII–XI	0
XII	1 + 1	sal