Megalothorax carpaticus, Papáč, Vladimír & Kováč, Ľubomír, 2013

Papáč, Vladimír & Kováč, Ľubomír, 2013, Four new troglobiotic species of the genus Megalothorax Willem, 1900 (Collembola: Neelipleona) from the Carpathian Mountains (Slovakia, Romania), Zootaxa 3737 (5), pp. 545-575 : 551-557

Megalothorax carpaticus sp. nov.

Figs 17–31

Megalothorax sp. nov. Kováč et al. (2006) Megalothorax sp. 2 Papáč & Kováč (2012) Diagnosis. Mucronal lamellae smooth ( minimus -group). Connection of integumentary channels with linea ventralis on head circular. Unpaired chaeta a0 between the basis of antennae present; posterior part of head behind antennae with thickened macrochaetae. Basomedian field of labium with 3+3 chaetae, Sensory fields 2–6 with flame-shaped sensilla. Mesochaeta p4 on Th. III far posteriorly to wax rod crypt 2, a6/a5 on Th. III as macrochaetae. Spherical sensillum s3 on abdomen absent. Micro- or mesochaeta on subcoxae I (leg I) present. Manubrium with 4+4 dorsal chaetae (2+2 proximal, 2+2 distal). Retinaculum with 3+3 teeth.

Type material. Holotype: male on slide (No. 204–06), Slovakia, Bachureň Mts., Zlá diera Cave, Veronikina sieň Hall, surface of water pool, 23.iii.2006, leg. P. Ľuptáčik and A. Mock. Paratypes: 23 ex.— 6 males, 12 females, 5 juveniles on slides (No. 204–06), same data as in holotype. Type material (holotype and 6 paratypes) saved in collection of MNHN, Paris. Other paratypes saved in collection of PJSU, Košice, Slovakia.

Other material. Slovakia, Bachureň Mts., Zlá diera Cave, 1 ex.—female on slide (No. 179–06), Veronikina chodba Corridor, pitfall trap, 13.x.2005 – 23.iii.2006, leg. A. Mock.

Čierna Hora Mts., Kolónia II Cave, 1 ex.—female on slide (No. 25–11) „Sieň“, pitfall trap, 6.iii.2010 – 2.iii.2011, leg. A. Mock. Lukáčova Abyss, 1 ex. (No. 831–11), „Dolná sieň“, pitfall trap, 8.vii.–4.xi.2011, leg. A. Mock.

Hornádska Basin, Pleky Cave, 1 ex.—female on slide (No. 726–12), lower passage, surface of water pool, 27.ix.2012, leg. A. Parimuchova; 1 ex.— 1 female on slide (No. 727–12), upper passage, surface of water pool, 27.ix. 2012, leg. M. Rendoš; 1 ex.— 1 female on slide (No. 728–12), direct collecting from stone, 27.ix. 2012, leg: A. Parimuchova.

Kozie chrbty Mts., Važecká Cave, 1 ex.—female on slide (No. 33–01), Čarovná záhradka Hall, surface of water pool, 17.v. 2001, leg. P. Ľuptáčik; 1 ex.— 1 juvenile on slide (No. 33–02), „Križovatka“ (Crossroad), surface of water pool, 9.v.2002, leg. Ľ. Kováč; 1 ex.—male on slide, „Križovatka“, surface of water pool, 24.x.2002, leg. Ľ. Kováč. Brada Cave, 1 ex.—female on slide (No. 76–01), main corridor, 40 m from entrance, pitfall trap, 17.v. 2001 – 13.ix.2001, leg. Ľ. Kováč

Levočské Mts., Jaskyňa pod Spišskou (Cave under Spišská Mt.), 3. ex. on slides (No.944–12), bottom of entrance shaft, surface of water pool, 11.x. 2012, leg. A. Parimuchova; 1 ex. on slide (No. 945–12), Jazierková chodba Passage, surface of water pool, 11.x. 2012, leg. A. Parimuchova. Jaskyňa pod Jankovcom (Cave under Jankovec), 1 ex (No. 153–11), „Sieň 1“, clay debris, pitfall trap, 5.xi.2010 – 1.iv.2011, leg. A. Mock; 1 ex. (No. 160– 11), narrow and steep passage, pitfall trap, 5.xi.2010 – 1.iv.2011, leg. Ľ. Kováč.

Low Tatras, Demänovská jaskyňa mieru (Demänovská Cave of Peace), 1 ex.—female on slide (No.790–11), near the entrance, water surface, 6.ix.2011, leg. P. Ľuptáčik.

Pieniny Mts., Aksamitka Cave, 2 ex.—females on slides (No. 257–12), Dóm priekopníka (Dome of Explorer), extraction of bait, 15.ix. 2011 – 8.v. 2012, leg. Ľ. Kováč.

Slovak Karst, Silická Plateau, Gombasecká Cave, 1 ex.—juvenile on slide (No. 341–07), Blatistá chodba Passage, 250 m from cave entrance, direct collecting from rotten wood, 6.x. 2007, leg. Ľ. Kováč.

Spišsko-gemerský Karst, Muráň Plateau, Rysie Hniezdo Cave, 1 ex.—female on slide (No. 74–07), bottom of the cave, aphotic zone, 150 m from the cave entrance, rocky debris with wood, pitfall trap, 28.v.–15.x.2007, leg. V. Papáč. Bobačka Cave, 1 ex on slide (No. 420–11), near „Veľryba“ (Whale), pifall trap, 9.v.–5.ix.2011, leg. A. Mock. Slovak Paradise, Dobšinská Ice Cave, 1 ex.—on slide (No.56–05), Kvapľová sieň Hall, surface of water pool, 22. iv.2004, leg. Z. Višňovská.

Veľká Fatra Mts., Harmanecká Cave, 1 ex.—male on slide (No.552–12), Nánosová chodba Corridor, surface of water pool, 18.ix.2012, leg. A. Parimuchová.

Description. Body length 0.45–0.6 mm, males smaller than females (up to 500 µm; Table 1 ), habitus typical of the genus. Body colour white, with black and bluish dots of pigmentation on head, thorax, abdomen and subcoxae. Cuticle finely granulated, integumentary channels observed on ventral side of head and dorsally on fore and back parts of head, connection of channels with l. v. ventrally on head circular.

Head. Head length and width as 165 and 155 µm, respectively. Dorsal chaetae smooth and pointed ( Fig. 17 ); unpaired chaeta a0 between the basis of antennae as microchaeta (6 µm). Frontal part with ordinary chaetae (8–10 µm) and 1+1 lateral chaetae between labial palp and basis of antenna (15 µm), posterior part with stouter, thickened macrochaetae (16–18 µm) and 2+2 mesochaetae (10–12 µm). Clypeo-labral formula: a0, 2, 4, 5, 4 / 5, 5, 4 ( Fig. 17 ). Pattern of labral chaetae: a-row 2R1 + 2R2, m-row m + 2r1 + 2r2 and p-row with 5 ordinary chaetae. Anterior labral chaetae R1 and R2 thick, curved; R2 longer than R1 (14 and 10 µm, respectively). Chaeta R1 medially with strong teeth, R2 with external edge finely serrate in its distal half. Medial (m-row) and posterior chaetae (p-row) equal (10 µm) and smooth. Integumentary channels present dorsally and ventrolaterally on fore and back parts of head ( Fig. 59 , a). Basomedian field of labium with 3+3 chaetae ( Fig. 21 ), medial chaetae longer (18 µm) than others (15 µm). Ventral side of head with 3+3 smooth postmedian macrochaetae ( Fig. 21 ): 2+2 anterior equally long (20 µm), 1+1 posterior chaetae shorter (16 µm). Basolateral field with 1 ordinary chaeta, oral fold with 2 chaetae. Mandible normal, strong with 5 apical teeth ( Fig. 18 ). Maxillary outer lobe with 1 enlarged terminal chaeta, 1 basal chaeta and 2 sublobal hairs ( Fig. 19 ). Maxilla with 1 lamella extending beyond fringed lamellae ( Fig. 20 ).

Thorax and abdomen ( Fig. 22 ). Dorsal side of thorax and abdomen with meso- and macrochaetae (8–10 µm and 14–25, respectively) and 8+8 wax rods (wrc1–8) as tiny, straight chaetae (2 µm) placed in small cuticle depressions. Th. II with 8+8 chaetae around thoracal sensory fields and 4+4 lateral chaetae around sensory fields at leg II base; 1+1 lateral sensillum s1. Th. III medially with 7+7, and 4+4 wrc, laterally at leg III base 3+3 chaetae and 2+2 wrc around sensory field; chaeta p4 more posteriorly to wrc2; chaeta a6 stouter and longer than a5. Abd. I– V with 19+19 dorsal chaetae, 2+2 wrc and 1+1 globular sensillum s2, chaeta β4 missing. Abd. VI dorsally with 9 chaetae ( Fig. 22 b). Anal field with 3 anal valves, each with 1 chaeta. Abd. VI with 9+9 ventral chaetae (2+2 axial shorter). Female genital plate on Abd. V sternum furnished with 2+2 chaetae ( Fig. 22 b). Male genital plate with 7+7 to 9+9 chaetae in circle formation and group of 3+3 lateral chaetae ( Fig. 25 ). Manubrium base (Abd. IV sternum) with 2+2 chaetae and lateraly with 2+2 broad neosminthuroid chaetae with bristle at tip (8 µm; Fig. 22 ).

Appendages. Antennal segments III and IV not separated ( Fig. 26 ). Length of antennae up to 106 µm, ratio antenna/head = 0.57. Lengths of antennal segments I, II, III–IV as 13, 15, 67 µm, respectively. Ant. I furnished with 1 short chaeta (6 µm). Ant. II with 4 chaetae arranged in whorl, 1 of them distinctly longer and stouter than others (13 µm vs. 6 µm). Ant. III with 9 ordinary chaetae, 2 of them in proximal position. Ant. III organ consists of 2 ovoid sensilla with striate structure (10 µm) and 2 long, transparent sensilla Sg in external and dorsal position (14 µm each). Ant. IV with 8 ordinary chaetae arranged mostly on internal side, external side with 10 thin and curved macrosensilla S finely blunt at the tip (20 µm); ventrally with 1 long and thick sensillum Sy (20 µm), 1 short, thick sensillum Sx (7 µm) with curved tip and 1 ordinary chaeta x; dorsally with cup-like subapical organite Or (3 µm); subapically with 7 ordinary chaetae (6 µm) and apically with 2 rod-like chaetae a and sa (10–12 µm). Complete chaetotaxy of antenna provided in Table 3. Chaetae numbers of legs I–III ( Figs. 28–30 , 22 ), longer chaetae in parenthesis: scx I: 1, 1, 2(2); scx II: 0, 1, 1(1); coxae: 1, 1(1), 1(1); trochantera: 3, 3, 4; femora: 7 (2), 7 (3), 8(2) and tibiotarsi: 12, 12, 11. Thin meso- or microchaetae in following numbers on leg I: coxa with 1, trochanter with 3, femur with 3; on leg II: trochanter with 1; on leg III: femur with 1. For complete chaetotaxy of legs see Table 4. Unguis narrow and elongated, both unguis and unguiculus unequally long in leg I, II, III: unguis 21, 19 and 17 µm, respectively, unguiculus 12, 11 and 11 µm, respectively. Length ratio unguis I (inner margin) / Ti. I width (21/15 µm) = 1.40. Unguis furnished with 2 lateral teeth la, lp and 1 long inner tooth Bp in basal 1/3. Unguiculus untoothed without apical filament; basal tubercle present, slightly projecting basal lamellae ( Fig. 31 ). Tubus ventralis with 2+2 distal chaetae, posterior lobe absent ( Fig. 23 ). Retinaculum with 3+3 teeth, chaeta on corpus absent ( Fig. 24 ). Furca well developed ( Fig. 27 ), length of manubrium, dens (proximal, distal part) and mucro: 55, 26, 38 and 39 µm, respectively. Manubrium dorsally with 4+4 chaetae, 2+2 proximal ones longer (10–12 µm) than 2+2 distal (7 µm). Proximal part of dens (dp) with 1+1 dorsal chaetae (7 µm). Distal part of dens (dd) dorsally with 1 medial, smooth chaeta (7 µm) and 4 broad spines with apical filament (6 µm): 2 external and 2 internal; ventrally with 3 tight apical spines in transversal row (5 µm; Fig. 27 ). Dental spines as leave-shaped integumental structures lacking basal circle. Mucro with both dorsal lamellae smooth, constricted at distal part, blunt at the tip; length up to 44 µm, width in the middle part 6 µm.

Sensory fields. 6+6 s.f. ( Fig. 17 , 22 ) placed in crater-like depressions each with secretory rod (8 µm), i.e. blunt, straight chaeta with basal part inserted in cuticle in upper margin of the field. S.f. have following arrangement: (a) anterior and posterior field on head (s.f. 1 and 2, 15 x 10 µm, 20 x 10 µm respectively; Fig. 17 ), posterior field with 1 internal spine (3 µm); (b) thoracal field (s.f. 3, 25 x 20 µm; Fig. 22 e) with 3 internal flame-shaped spines (1 greater curved—4 µm, 2 smaller—3 µm) and 6 external chaetae (3 macrochaetae—14–22 µm, 3 mesochaetae—8– 10 µm); (c) abdominal field (s.f. 6, 25 x 20 µm; Fig. 22 a) with 1 internal flame-shaped, curved spine (4 µm), 5 external macrochaetae (16–22 µm) and 1 spherical sensillum s2 (4 µm); (d) field at base of leg II (s.f. 4, 20 x 12 µm; Fig. 22 d) with 2 internal flame-shaped spines (3 µm), 4 external chaetae (18–20 µm) and 1 curved microsensillum s1 (6 µm) above the field; (e) field at base of leg III (s.f. 5, 20 x 12 µm; Fig. 22 c), with 2 internal flame-shaped spines (3 µm), 3 external macrochaetae (18–24 µm) and wax rods wrc 5,6 on its posterior margin.

Both sexes known. Except genital plates no other sexually dimorphic characters observed.

Etymology. The new species is named after the Carpathian Mountains, since its likely wider distribution in caves of the whole mountain range.

Ecology and distribution. Up till now M. carpaticus sp. nov. is known from altogether 14 caves, its broader range covering karstic as well as non-karstic caves of the Western Carpathians. The new species was sampled at cave entrances and also in deeper parts of the caves, mainly on surface of water pools. Interesting is syntopy of M. carpaticus sp. nov. and M. hipmani sp. nov. (described below) in water pools in three rather distant caves - Demänovská Cave of Peace (Low Tatras Mts.), Važecká (Kozie chrbty Mts.) and Harmanecká (Veľká Fatra Mts.).

Discussion. M. carpaticus sp. nov. belongs to „ minimus -group“ by smooth edges of mucro and modified internal chaeta of sensory fields in form of flame-shaped spine. It is very similar to M. willemi and M. tatrensis sp.

nov. M. carpaticus sp. nov. differs from M. willemi by several morphological characters that may be assumed as adaptations to life in cave environment, i.e. larger body, elongated ungua on legs, elongated mucro, antennae, and body chaetae. In M. willemi strong flame-shaped spine in s.f. 6 reaches half the sensory field length, whereas in M. carpaticus sp. nov. the spine is smaller. M. carpaticus sp. nov. differs from M. tatrensis sp. nov. by combination of characters such as presence of thickened posterior macrochaetae on head dorsum (ordinary chaetae in M. tatrensis sp. nov.), presence of micro- or mesochaeta on scx I (as macrochaeta in M. tatrensis sp. nov.) and mucro constricted in distal third and blunt at apex (gradually narrowing with pointed apex in M. tatrensis sp. nov.). For other diagnostic characters see Tables 3–5.

Figures

FIGURES 17 – 21. Megalothorax carpaticus sp. nov.: 17, head, dorsal side, chaetae of anterior row enlarged; 18, mandible; 19, maxillary outer lobe; 20, head of maxilla; 21, ventral side of head with labium and connection of integumentary channels with linea ventralis.

FIGURES 22 – 25. Megalothorax carpaticus sp. nov.: 22, chaetotaxy and arrangement of sensory fields on thorax and abdomen, a—abdominal sensory field (enlarged), b—Abd. V – VI with anal and female genital field (av—anal valve chaetae), c—sensory field at leg III base (enlarged), d—sensory field at leg II base (enlarged), e—thoracal sensory field (enlarged); 23, tubus ventralis; 24, retinaculum; 25, male genital plate.

FIGURES 26 – 27. Megalothorax carpaticus sp. nov.: 26, right antenna, dorsal view (sensillum of Ant. III organ and apical organite enlarged); 27, furca, posterior view, a—lateral view of mucro.

FIGURES 28 – 31. Megalothorax carpaticus sp. nov.: 28, leg I; 29, leg II; 30, leg III; 31, unguis and unguiculus of leg I.

FIGURES 58 – 61. Integumentary channels on head: 58, Megalothorax tatrensis sp. nov. — dorsally; 59, Megalothorax carpaticus sp. nov. — dorsally, a—ventrolateral view of head with integumentary channels; 60, Megalothorax hipmani sp. nov. — on headback; 61, Megalothorax draco sp. nov. — dorsally and laterally on headback.