Arrhopalites prutensis, Vargovitsh, Robert S. & Buşmachiu, Galina, 2015

Vargovitsh, Robert S. & Buşmachiu, Galina, 2015, A new species and new records of Arrhopalitidae (Collembola: Symphypleona) from the Republic of Moldova, Zootaxa 3973 (3), pp. 539-552 : 540-550

Arrhopalites prutensis sp. nov.

Figs 2–31 , Tables 1 , 2

Diagnosis. Body compact, white, with short appendages and setae, total length about 0.6 mm. Trichobothria ABC form right angle and AB = 2 BC. Head dorsum with 13 moderately spine-like setae. Antenna about 1.2× of head length. Ant III swollen subbasally, Ant IV undivided. All claws with inner tooth, II–III with tunica. Empodium I–II with and III without corner tooth. Tips of empodia not reaching tips of corresponding claws. Manubrium with 5 + 5 setae. Anterior surface of dens with 3, 2, 1, 1 thick setae; posterior surface with 11 setae, 5 of which are spine-like. Furca base region (Abd IV) with 1 + 1 short spine-like neosminthuroid setae; Abd VI with 4 + 4 small cuticular spines and with strong but not lamellate circumanal setae. Appendices anales rod-like, apically serrated.

Type material. 5 specimens on 3 slides. Holotype on slide B-5: female, Republic of Moldova, Leuşeni (46°46'36"N, 28°10'29"E) ( Fig. 1 point 1), forest belt of the water protection on the bank of Prut River, 12.x.2006, leg. G. Buşmachiu. Holotype is deposited in the collection of the Schmalhausen Institute of Zoology, NAS of Ukraine, Kiev. Paratypes: moulting female and juv., same locality as holotype, 11.v.2006 (slide B-3); juv., same data as holotype (slide B-5); female, Republic of Moldova, Branişte (47°49'1"N, 27°13'2"E) ( Fig. 1 , point 2), forest belt of the water protection on the bank of Prut River, 11.x.2006 (slide B-16). Paratypes are deposited in the collection of the Schmalhausen Institute of Zoology, NAS of Ukraine, Kiev and in the Entomological Museum of the Institute of Zoology of Academy of Sciences of Moldova.

Description. Female. Body length about 0.6 mm (580 Μm in holotype), without traces of pigmentation in alcohol, habitus as in Fig. 2 .

Head ( Figs 3 , 27 ). 1 + 1 very small eyes, 4.2 Μm in diameter. Interantennal area (rows α and β) with axial seta in row β. Dorsal area (rows A to D): 3 axial setae in rows A, B and C; 13 setae moderately spine-like ( Fig. 7 ) in row A: 1 + 1, B: 1 + 1, C: 2 + axial + 2, D: 2 + 2; other setae are not modified.

Mouthparts. Labral / prelabral chaetotaxy: 4 5 5 / 6. Proximal / basomedian / basolateral fields of labium with 5 / 4 / 5 setae. Labial palp as in Fig. 4 , one seta of papilla B sensilla-like and S-shaped. Maxillary outer lobe with 3 sublobal hairs ( Fig. 5 ).

Antenna ( Fig. 6 ) short, 1.2× of head. Mean length ratio of antennal segments I: II: III: IV = 1: 2.2: 3.2: 4.8. Ant I with 6 anterior setae and small posterior microseta. Ant II with 14 setae, one of which (19 Μm in holotype) is sensilla-like and about 2.5× longer than other setae which are somewhat spine-like. Ant III is massive, broadened in subbasal and median part ( Fig. 26 ) and with following chaetotaxy: 16 simple setae, 2 sense rods (3.7 Μm in holotype) in shallow pits and Aai as small bent and blunt sensillum. Ant IV short and undivided, bears 12 densely settled whorls of setae without empty spaces between them.

Foreleg ( Fig. 16 ). Precoxae 1, 2 and coxa with 1, 0, 1 setae respectively ( Fig. 22 ). Trochanter with 3 anterior and 1 posterior setae. Femur with 11 setae, a4 turned perpendicularly to longitudinal axis of segment, p3 as microseta. Tibiotarsus with 41 setae: whorl I with 8 setae, of them Ja is spiny and curved, whorl II with 7 setae, each of whorls III–IV with 8 setae, whorl V with 7 setae and region F with 3 primary setae (e, ae, pe). Foot complex ( Fig. 19 ). Claw: without tunica; with inner tooth, 4.3–4.5× shorter than tibiotarsus. Empodium: thin, with distinct corner tooth, 1.6–1.8× shorter than claw; tip of empodial filament not reaching tip of claw.

Mid leg ( Fig. 17 ). Precoxae 1 and 2 with 1, 1 setae respectively, precoxal process present, coxa with 3 setae and microsensillum. Trochanter with 4 setae including 2 simple anterior and 1 posterior setae and anterior trochanteral organ. Femur with 13 setae. Tibiotarsus with 40 setae: distal whorl I with 8 setae, whorls II with 7 setae, whorls III–IV with 8 setae, whorl V with 6 setae, basal region F with 3 FP setae. Foot complex ( Fig. 20 ). Claw: tunica and inner tooth present, 4.3–4.7× shorter than tibiotarsus. Empodium: broader than in foreleg, with corner tooth, 1.8× shorter than claw; empodial filament short and not reaching tip of claw.

Hind leg ( Fig. 18 ). Precoxae 1 and 2 with 1, 1 setae respectively, process on precoxa 1 present, coxa with 3 setae and microsensillum. Trochanter with 5 setae: anterior trochanteral organ, 3 anterior and 1 posterior simple setae. Femur with 14 setae, 2 posterior ones as microsetae. Tibiotarsus with 43 setae: whorls I–IV with 8 setae, whorl V with 7 setae (Vp absent), region F with 3 primary setae FP and secondary seta FSa. Foot complex ( Fig. 21 ). Claw: with well-developed tunica and with inner tooth, 5.5× shorter than tibiotarsus. Empodium: broad, corner tooth absent, 1.7× shorter than claw; tip of empodium not reaching tip of claw.

Mean lengths ratio of tibiotarsi I: II: III = 1: 1: 1.3. Tibiotarsus I about 2× shorter than head.

Ventral tube with 1 + 1 subapical microsetae. Tenaculum ( Fig. 23 ): each ramus with 3 teeth and basal process; anterior lobe with 1 apical seta.

Furca ( Fig. 24 ). Manubrium with 5 + 5 posterior setae. Dens with 18 setae. 3, 2, 1, 1 heavy setae on anterior side, Ia – not thicker than two other a setae ( Fig. 15 ). Posterior side bears 11 setae, 5 of which are distinctly spinelike: Ie, Ipe–IIIpe, Ii. Mucro: lateral lamellae serrated with about 18 teeth per side, with globular apex ( Fig. 28 ). Dens about 1.7× as long as mucro.

Great abdomen ( Fig. 22 ): Th II bears single sensillum in row a ( Fig. 8 ) and 3 setae in row m with m1 and m2 somewhat spine-like ( Fig. 9 ). Th III with sensillum in row a and 4 setae in row m. Abd I bears single row with 5 setae. Trichobothrial complex ( Fig. 30 ): ABC form about right angle (86°–102°) and AB is 2.1–2.3× of BC; p seta is located on the level of trichobothrium B; seta b1 lies almost on line BC, closer to C; microseta c1 (3.8–4.5 Μm) lies in front of and seta c2 —below the trichobothrium C. Posterior lateral complex with 6 setae. Furca base complex with 8 setae, one of which is modified into short (5.5–6.6 Μm) spine-like smooth neosminthuroid seta ( Figs 10 , 29 ). Central dorsal complex with 3 subequal setae. Posterior dorsal complex arranged in 3 longitudinal rows with about 20 relatively short setae, the longest of which (about 20 Μm) is subequal to hind claw or a little shorter ( Fig. 11 ). Ventral complex with 3 setae.

Fifth abdominal segment ( Fig. 22 ) with 2 setae and trichobothrium D in row a, and 2 setae in row p. Genital field with 2 + 2 short setae along anterior margin of genital opening.

Sixth abdominal segment ( Figs 25 , 31 ) with 4 + 4 small cuticular spines: bigger on dorsal valve (4–5.5 Μm) and smaller (2–2.2 Μm) on lateral valves. Dorsal valve with 10 + 2 axial + 10 setae, ms5 absent. Each of lateral valves bears 18 setae. Circumanal row with 7 somewhat broadened but not lamellate setae per side: ms1 (axial) ( Fig. 12 ), mps1–mps3 and mpi1–mpi3, the longest of them are about 30–35 Μm and clearly longer than posterior setae of great abdomen ( Fig. 13 ). Appendices anales ( Fig. 14 ) (about 21 Μm) rod-like, not expanded, 10× as long as wide, apically denticulated; sitting on semiglobular papilla. In total, normally 58 setae and 8 cuticular spines on Abd VI are present.

Male. Not seen.

Bionomy and distribution. Arrhopalites prutensis sp. nov. was sampled from two wet sites along the bank of Prut River ( Fig. 1 ). In Leuşeni four specimens were extracted from soil in the forest belt, 12 m from the water edge of river bank and in soil under the blackberry bush, 6–8 m from the water edge. In Branişte the single female was also taken from soil in the forest belt on the river bank. Small size and short appendages indicate that this species is rather soil dwelling.

Etymology. The name of the new species is derived from hydronym Prut River on the bank of which the type locality is situated.

Remarks. The new species belongs to the diversus group according to anterior dens chaetotaxy (3, 2, 1, 1). It is close to Sicilian A. baccettii and A. antonioi with which shares presence of spine-like and smooth neosminthuroid seta, small body size and general habitus, short antenna with thick Ant III and undivided Ant IV, reduced chaetotaxy of dens dorsal side, strong but not winged circumanal setae, relatively long and thin appendices anales.

A. prutensis sp. nov. differs from A. baccettii by dorsal chaetotaxy of dens (IVpi absent vs present, so 11 setae vs 12), presence of corner tooth on empodium I (vs absence) and spine-like setae on head dorsum (vs slightly thicker than ordinary setae).

The new species differs from A. antonioi by several details of great abdomen chaetotaxy: 6 setae on posterior lateral complex vs 5; 8 setae on furca base complex vs 7; 4 setae in m row of Th III vs 2; 4 setae on row m of Abd II vs 5; seta p of thichobothrial complex is located on the level of trichobothrium B vs much above the level of B; seta 3 of dorsal complex simple vs sensilla. Besides, A. prutensis : bears 4 + 4 cuticular spines on Abd VI (vs absent), smooth circumanal setae (vs laterally serrated) and seta ms5 absent (vs present); lacks corner tooth on empodium III (vs present); tip of empodium I and II not reaching tip of corresponding claw (vs overtopping); reduced tibiotarsal chaetotaxy, in particular number of setae in whorl I (in all legs 8 setae vs 9) whorl II (7 setae in leg I and II vs 8) and whorl V (7 and 6 setae in legs I and II respectively vs 8 and 7).

Some differences between new species and similar congeners are given in Table 2 .

Material. 1 juv. (immature female?), Republic of Moldova, Stejăreni, Codrii Scientific Reserve (47°4'23"N, 28°27'37"E) ( Fig. 1 , point 3), Querceto-Carpinetum, 13.v.1998, leg G. Buşmachiu.

Description. Some morphometric data are given in Table 1 . Body length 0.48 mm.

Head dorsum with 13 spine-like setae ( Fig. 38 ). Maxillary outer lobe with 3 sublobal hairs ( Fig. 33 ).

Antenna 1.42× of head. Ratio of antennal segments I: II: III: IV = 1: 2.5: 3.75: 6.5. Ant II with 14 setae, one of which (31 Μm) is sensilla-like and 5 times longer than others ( Fig. 38 , marked with arrow). Ant III: with unusual for the genus finely granulated oval field 7.2×8.7 Μm (“sensory field”?) in basal part ( Fig. 32 c), symmetrically present on left and right antennae and surrounded by 4 short setae: 2 – close to the margin and 2 – more distant; chaetotaxy as in Fig. 32 a,b. Ant IV undivided.

All claws ( Fig. 35 a,b,c) with inner tooth, claws II and III with tunica. Tips of empodia not reaching tips of corresponding claws, empodium III without corner tooth. Lengths ratio of tibiotarsi I: II: III = 1: 1: 1.17. Tibiotarsus of fore leg 2× shorter than head.

Corpus of tenaculum with 1 apical seta.

Furca. Manubrium with 5 + 5 posterior setae. Dens with 19 setae. 3, 2, 1, 1 heavy setae in anterior side ( Fig. 36 a), Ia not spine-like. Posterior side with 6 spine-like setae Ie, Ipe–IIIpe, Ii and IVi ( Fig. 36 b). Mucro: lateral lamellae serrated with about 12 teeth per side, with globular apex ( Fig. 36 b). Dens 1.7× as long as mucro.

Great abdomen. Single sensillae of row a on Th II and Th III are subequal and relatively long (both 7.8 Μm). Trichobothrial complex as in Fig. 39 : ABC form an angle close to right (98o), seta p lies on the level of B. Posterior lateral complex with 6 setae. Furca base complex with 8 setae, one of which is modified into elongated (11 Μm) neosminthuroid seta lying in long socket ( Fig. 34 ).

Abd V with trichobothrium D and 4 ordinary setae.

Abd VI ( Fig. 37 ): circumanal setae strong, slightly broadened and a little longer than posterior setae of great abdomen; dorsal valve with 9 + 2 axial + 9 setae, mps3 and ms5 absent; cuticular spines absent.

Bionomy and distribution. The single specimen was extracted from the soil + litter sample from the Codrii Scientific Reserve ( Fig. 1 ). Small size and short appendages indicate that this species is rather soil dwelling.

Remarks. Examined specimen is not adult: it lacks appendices anales (female character of sexual dimorphism) as well as ductus ejaculatus and group of numerous short setae around genital opening (male characters of sexual dimorphism); meanwhile, presence of somewhat broadened circumanal setae may indirectly and tentatively indicate that it should be an immature female. Arrhopalites sp. possesses a set of characters which allows to separate it from all other species of the genus. It belongs to the diversus group with 3, 2, 1, 1 anterior dens setae and it is the fourth species of the genus possessing neosminthuroid setae. From three closely related species of diversus group it differs by the elongated shape of neosminthuroid seta (vs short spine-like), presence of finely granulated “sensory field” on Ant III basis (vs absence), presence of seta on Ant II about five times longer than other setae of segment (vs 2.5 times or less) and other characters ( Table 2 ). Additional material (adult females) is required to complete description of chaetotaxy and to clarify its taxonomic status.

Besides two species given above, other new findings of Arrhopalitidae from Moldova were done and their records are listed below.

Figures

FIGURES 1 – 2. 1, places of findings of Arrhopalites prutensis sp. nov. (point 1 — Leușeni, 2 — Braniște) and Arrhopalites sp. gr. diversus (point 3 — Stejăreni); 2, Arrhopalites prutensis sp. nov., habitus of mounted holotype.

FIGURES 3 – 15. Arrhopalites prutensis sp. nov.: 3, chaetotaxy of head dorsum; 4, chaetotaxy of labial palp; 5, sublobal hairs of maxillary outer lobe; 6, chaetotaxy of antenna; 7 – 15, shape of setae: 7, spine-like seta of head vertex; 8, sensilla a of Th II; 9, m 1 of Th II; 10, neosminthuroid seta of Abd IV; 11, dII- 1 of great abdomen; 12, ms 1 of Abd VI; 13, mps 2 of Abd VI; 14, appendices anales; 15, Ia of dens.

FIGURES 16 – 21. Arrhopalites prutensis sp. nov.: chaetotaxy of legs, anterior view: 16, foreleg; 17, mid leg; 18, hind leg; 19, fore claw; 20, mid claw; 21, hind claw.

FIGURES 22 – 25. Arrhopalites prutensis sp. nov.: 22, chaetotaxy of great abdomen; 23, tenaculum; 24, chaetotaxy of furca, lateral view; 25, chaetotaxy of Abd VI, setae of circumanal row are filled with grey colour.

FIGURES 26 – 31. Arrhopalites prutensis sp. nov.: 26, proximal part of antenna with swelled Ant III; 27, head dorsum with spine-like setae; 28, mucro, lateral view; 29, neosminthuroid seta; 30, chaetotaxy of trichobothrial complex; 31, Abd VI with cuticular spines (marked with arrows), lateral view.

FIGURES 32 – 39. Arrhopalites sp. gr. diversus: 32, Ant III (a—posterior side, b—anterior side, c— “ sensory field ”); 33, maxillary outer lobe with sublobal hairs; 34, neosminthuroid seta; 35, foot complex (a—fore, b—mid, c—hind); 36, furca (adens, anterior side, b—dens and mucro, posterior side); 37, Abd VI, lateral view; 38, head, frontal side; 39, chaetotaxy of trichobothrial complex.

Tables

TABLE 1. Lengths (in µm) for body parts of type specimens (3 females) of Arrhopalites prutensis sp. nov. and single immature specimen of A. sp. gr. diversus.

Body part	A. prutensis sp. nov.	A. sp.
	min–max mean	1 specimen
Body total	580–630 597	480
Head	190–206 200	182
Eye diameter	4.1–4.2 4.2	3.7
Antenna	220–251 239	259
Ant I	20–24 22	20
Ant II	46–52 49	50
Ant III	71–79 75	75
Ant IV	101–117 109	130
Tibiotarsus I	85–95 92	89
Tibiotarsus II	85–100 93	89
Tibiotarsus III	102–130 117	104
Claw I	19–22 21	19
Claw II	18–22 20	17
Claw III	19–23 21	17.5
Empodium I	11–14 12	11.7
Empodium II	10–12 11	9.5
Empodium III	10–14 12	9.5
Manubrium	78–90 84	86
Dens	76–86 82	84
Mucro	44–50 48	49
AO-III rods	3.7–4.7 4.1	3.2
Head longest spiny seta	10.1–10.5 10.3	6.9
Ant II longest sensilla-like seta	18.2–19 18.6	31
Th II dorsal seta	11.2–13.8 12.2	8.5
Th II sensilla a	6.4 6.4	7.8
Th III sensilla a	4.2–4.8 4.6	7.8
Abd seta c1	3.7–4.5 4.2	3.2
Great Abd longest seta (dIII-1)	18–23 20	20.5
Abd VI longest seta	25–35 31	22.7
Circumanal spine s1-s2	4–5.6 4.8	absent
Circumanal spine s3-s4	2–2.3 2.1	absent
Appendices anales	17–21 20	absent
Dens seta Ia	9–12 10	9.8

TABLE 2. Differences between species of Arrhopalites from diversus group with neosminthuroid seta.

Character / Species L body, mm Ant III basal sensory field	A. prutensis sp. nov. A. sp. 0.6 (female) 0.48 (immature) - +	A. baccettii 0.6 (female) -	A. antonioi 0.6–0.8 (female) -
Longest/regular seta of Ant II Shape of neosminthuroid seta Position of seta p in trichobothrial complex Dorsal dens setae	~2.5× ~5× short spine-like elongated on level of B on level of B 11 12	? short spine-like? 12	~1.5× short spine-like much above B 11
IVpi of dens Head spiny setae Emp tooth I; II; III	- + + + + + -? + -	+ very weak - + -	- + + + +
Emp tip: claw tip I; II; III Cuticular spines on Abd VI ms5 of Abd VI	<<<<<<4 + 4 - - -	<<<4 + 4 -	>> ≤ - +
Circumanal setae	smooth smooth	smooth	serrated
Arrhopalites sp. gr. diversus Figs 32–39, Tables 1, 2