Allacrotelsa taurica Kaplin, 2023

Kaplin, V. G., 2023, A new species of the silverfish genus Allacrotelsa Silvestri, 1935 (Zygentoma: Lepismatidae) from Crimea, Far Eastern Entomologist 471, pp. 19-28 : 20-27

Allacrotelsa taurica Kaplin sp. n.

https://zoobank.org/NomenclaturalActs/ 7593858E-BDB5-48A4-831F-403F372CD596

Figs 1–28

TYPE MATERIAL. Holotype – ♂ (in slides), Crimea : Noviy Svet: 44°50′ N, 34°55′ E, h = 110 m, in leaf litter among stones under Quercus pubescens , Juniperus oxycedrus , and Carpinus orientalis forest, 24. V 2021, leg. V. Kaplin ( VIZR) (in slides). Paratypes: 3♀, 2 ♂, same locality, data and collector as for holotype [2♀ and 1 ♂ in slides, 1♀ and 1 ♂ in 75% ethanol] ( VIZR).

DESCRIPTION. Appearance: Medium-sized silverfish ( Fig. 1 ), scales on the upper side of the body grayish-brown, on the lower side light brown.

Body length (including head) 7.8–8.5 mm (♀), 9.8–11.3 mm (♂); ratio lengths of head to body about 0.07–0.08, thorax to body about 0.31–0.32. Width of head about 1.3 mm (♀), 1.4 mm (♂); width of thorax, respectively, about 2.35 mm and 2.65 mm, urite IX about 1.3 mm and 1.4 mm. Antennae damaged in all specimens, maximum preserved length of antenna 6.3 mm (or 0.81× body length) (♀), 8.3 mm (0.79× body length) (♂); terminal filaments damaged in all specimens, maximum preserved length of cercus 5.8 mm (or 0.75× body length) (♀), 7.3 mm (0.70× body length) (♂). Body neither elongate nor broad, thorax slightly wider than abdominal segment I.

Pigment light purple-chestnut-brown in alcohol-preserved specimens, stronger on the first tarsomere, tibia and femur; on maxillary and labial palps; labium, mandible, on head surrounding the eyes; pedicel and abdominal stylets. Urites IX and X with dense pigmentation in paraprocts and epiproct, cerci and median dorsal appendage with strong dark rings of pigmentation. Weaker pigment on clypeus, labrum, maxilla, trochanter, coxa, urotergites I–VIII, male genital appendages.

Macrochaetae smooth, bifid apically, hyaline or slightly straw-coloured. Scales multiradiate of variable shape, rounded, oval, suboval, fan-shaped ( Fig. 2 ); absent from flagellum, maxillary and labial palps, styli, caudal appendages.

Head wider than long, eyes dark well developed, composed of about 12 ommatidia, their diameter about 0.20–0.25 mm. Macrochaetae along the anterior and lateral margins of the head well developed, relatively large, bifid apically. Anterior part of frons slightly concave, anterolaterally and laterally with large, apically bifid macrochaetae, such chaetae absent from concave area ( Fig. 3 ). Postclypeus with numerous medium-size, simple chaetae; anteclypeus glabrous. Posterior part of labrum with numerous smaller simple chaetae, anterior part of labrum with several chaetae forming an uneven row. Mandibles with well-developed molar and incisor areas, with 5 strong chitinized teeth (2 sharp, 1 wide and 2 small) ( Fig. 4 ); with numerous, relatively long apically bifid macrochaetae on molar area and a row of shorter lateral chaetae including about 7 apically bifidchaetae near molar area. Maxilla without special characters, lacinia with three strong teeth, 6 lamellate processes in both sexes and a row of 8 to 10 chaetae in female and 7 simple chaetae in male. Galea with lateral row of 11–17 thin chaetae and 3–5 small sensory chaetae. Apical article of maxillary palp 1.02–1.15 times longer than penultimate article. Distal part of the third article of maxillary palp with 1 or 2 strong conical simple spines in both sexes ( Fig. 5 ). Labial palps well developed, apical article oval with 2 + 3 papillae ( Fig. 6 ); ratio of apical article length to width approximately 1.8–2.0 in both sexes.

Pronotum near the anterior margin with 1 + 1 sublateral groups of relatively long apically bifurcate macrochaetae including about 12 chaetae in both sexes. Lateral anterior corners of pronotum also with 12–16 + 12–16 such macrochaetae. Chaetal collar on the anterior margin of pronotum largely absent except for the more sublateral groups. Near the anterior margin of pronotum between these sublateral groups of macrochaetae instead of chaetal collar there is a collar formed by many scales. Lateral margins of pronotum with apically bifurcate short and long macrochaetae and 5 + 5 open trichobothrial areas each with one thin and very long trichobothrium ( Fig. 7 ). Lateral margins of mesonotum and metanotum as pronotum with a row of apically bifurcate macrochaetae. Lateral margins of mesonotum also with 8–9 + 8–9 bristle combs, metanotum with 6–7 + 6–7 combs of such macrochaetae including mainly two chaetae, but the first and last combs with 3 or 4 macrochaetae and with respectively 3 + 3 and 2 + 2 open trichobothrial areas in their posterior half with one long trichobothrium ( Figs 8, 9 ). Posterior margins of thoracic nota concave, without macrochaetae and any bristle combs. All thoracic sterna with hyaline scales. Prosternum and mesosternum sub-triangular, longer than wide at its base, metasternum semi-oval rounded apically and reaching almost to the end of the coxa ( Figs 10–12 ). Ratio of its length to width respectively about 1.10, 1.05 and 0.77. Lateral and apical margins of prosternum, distal half of mesosternum, distal quarter of mesosternum with relatively long simple chaetae. About 9 or 10 larger, apically bifid chaetae in basal corners of prosternum. Preapical parts of all sterna also with 1 + 1 combs including 4–6 bifid apically macrochaetae ( Figs 13, 14 ). Legs fairly long ( Fig. 15 ), increasingly longer from front to back. Ratio total length of PII to PI about 1.1, PIII to PII 1.2, PIII to PI 1.3 in male and respectively 1.2, 1.3 and 1.7 in female. All femora and coxae widened in both sexes ( Table 1 ). Tibia on dorsal margin and in distal part with 2 or 3, on ventral margin with 4 or 5 (foreleg), 5 or 6 (middle leg) and about 8 (hind leg) strong, stout, apically bifid macrochaetae. Femur on ventral surface with 6–12 apically bifid macrochaetae on distal part, with 2 or 3 apically bifid macrochaetae and 2 or 3 simple large, strong macrochaetae in both sexes. Trochanter lacking scales, only with chaetae. Coxa of all legs covered with hyaline scales and with numerous large and strong bifurcate macrochaetae along the outer margins. Tarsus with four articles. On ventral surface of tarsomeres two rows of hyaline simple spines. First, second and third tarsomeres respectively with 4–12, 4–6 and 2 spines, absent on the last tarsomere. Pretarsus with long curved lateral claws and a strong curved shorter medial claw.

On abdomen urotergites I and VIII with 2 + 2 bristle combs including respectively 3 or 4 and 4 or 5 macrochaetae, urotergites II–VII with 3 + 3 combs of 3–5 macrochaetae, urotergite IX with 1 + 1 combs of 2 macrochaetae ( Figs 16–18 , Table 2 ). Urotergite X parabolic, with 1 + 1 subapical combs of 3–5 macrochaetae in both sexes ( Fig. 19 ). Urosternites I–VII in female or I–VIII in male with one medial comb; urosternites II–VIII in male, urosternites II– VII and urocoxites VIII in female with 1 + 1 lateral combs ( Figs 20–22 ). Number of macrochaetae in medial combs on urosternites I–VII 3–6, on VIII 3; 5–9 macrochaetae in lateral combs in both sexes.

Styli in two pairs in both sexes (VIII, IX), their apical macrochaeta simple and strong, about 0.2× length of styli. Styli IX 1.3 times as long as styli VIII. Ratio lengths of styli and coxites IX about 0.9 in male and 0.6–0.7 in female. Ovipositor ( Fig. 23 ) not very long and thin, slightly surpassing the apex of stylus IX, composed of about 31 or 32 divisions. All divisions of anterior gonapophyses with chaetae, missing on one basal division of posterior gonapophyses. Chaetotaxy of gonapophyses as shown on Figs 24, 25 . Penis typical for Heterolepismatinae with numerous glandular setae apically, each set on a protuberance. Parameres well developed, 2.2 times longer than wide, composed of five divisions with thin chaetae and inner lateral glandular formations on three distal divisions with setae apically ( Fig. 26 ). Paraprocts with sharp-angled lateral projections ( Fig. 27 ). Epiproct with a well-defined triangular indentation ( Fig. 28 ).

DIFFERENTIAL DIAGNOSIS. Allacrotelsa taurica Kaplin sp. n. is very similar to A. kraepelini in number and distribution of bristle combs on abdominal tergites (I and VIII urotergites with 2 + 2, II–VII – with 3 + 3, IX and X – with 1 + 1 combs) and abdominal sternites (I–VII urosternites in female or I–VIII in male with one median, II–VIII – in male, II–VII urtosternites and VIII urocoxites in female with 1 + 1 lateral combs); two pairs of abdominal stylets (VIII and IX); well developed parameres in male. New species differs from A. kraepelini by the body size, morphological structure of labial palp, pronotum, prostenum, legs, ovipositor. Body length of A. taurica 8–11 mm, maximum length of A. kraepelini about 14 mm. Ratio of length to width of apical article of A. taurica sp. n. 1.8–2.0, A. kraepelini about 2.4. Pronotum of A. taurica sp. n. with 5 + 5, A. kraepelini with 3 + 3 lateral trichobotria. Ratio of length to width of prosternum A. taurica sp. n. 1.10, A. kraepelini 0.80. Ratio of length to width of coxa of hind leg of A. taurica sp. n. about 1.6, A. kraepelini 1.3. Ovipositor of A. taurica sp. n. includes 31–32, A. kraepelini 35–38 divisions.

ETYMOLOGY. The species name is an adjective referring to Taurida, an ancient name of the Crimea , where the holotype and paratypes were collected.

Figures

Figs 1–6. Allacrotelsa taurica sp. n., holotype ♂ (2, 3, 5, 6) and paratype ♂ (1); paratype ♀ (4). 1 – habitus; 2 – scales; 3 – head, front view; 4 – distal part of mandible; 5 – maxillary palp, with maxilla; 6 – labial palp, with labium. Scale bars = 0.1 mm.

Figs 7–14. Allacrotelsa taurica sp. n., holotype ♂. 7 – pronotum; 8 – mesonotum; lateral part; 9 – metanotum, lateral part; 10 – prosternum; 11 – mesosternum; 12 – metasternum; 13 – prosternum, distal part; 14 – mesosternum, distal part. Scale bars = 0.1 mm.

Figs 15–19. Allacrotelsa taurica sp. n., holotype ♂ (15–17) and paratype ♀ (18, 19). 15 – hind leg; 16 – urotergite I; 17 – urotergite II; 18 – urotergite VIII; 19 – urotergite X. Scale bars = 0.1 mm.

Figs 20–25. Allacrotelsa taurica sp. n., holotype ♂ (22) and paratype ♀ (20, 21, 23–25). 20 – urosternite I; 21 – urosternite II; 22 – urosternite VIII; 23 – urocoxite IX, with anterior gonapophyses; 24 – anterior gonapophysis, distal part; 25 – posterior gonapophysis, distal part. Scale bars = 0.1 mm.

Figs 26–28. Allacrotelsa taurica sp. n., holotype ♂. 26 – urocoxite IX, with genital appendages; 27 – paraprocts; 28 – epiproct. Scale bars = 0.1 mm.