Neelus lackovici, Papáč, Vladimír, Lukić, Marko & Kováč, Ľubomír, 2016

Papáč, Vladimír, Lukić, Marko & Kováč, Ľubomír, 2016, Genus Neelus Folsom, 1896 (Hexapoda, Collembola) reveals its diversity in cave habitats: two new species from Croatia, Zootaxa 4088 (1) : 61-68

Neelus lackovici sp. nov.

Figs 3, 19 –31, Tables 1 –4

Diagnosis. Cuticle finely granulated. Posterior part of head behind antennae with meso and macrochaetae. Posterior part of abdomen covered with meso- and macrochaetae. Anterior labral chaetae a1 and a2 thick, a1 medially with 2 strong teeth and serrate in distal half, a2 medially finely serrate. Sensory field on thorax furnished with 4 anterior lanceolate spines. Ant. I segment with 3 chaetae. Ant. IV segment with 12 S-chaetae with round apex. Unguis and antennae extremely elongated. Manubrium with 4+4 posterior chaetae. Mucro with posterior lamellae rather smooth with serrate irregularities, tip of mucro undivided, rounded.

Type material. Holotype: female on slide (No. CLL 4489), Croatia, Tounj, Špilja u kamenolomu Tounj Cave (coordinates WGS84 N45.24756° E15.31989°, alt. 300 m.), direct collection from the wet stone, 9.iv.2011, leg. M. Lukić and H. Bilandžija. Paratypes: 5 females and 1 male on slides (No. CLL 3049), the same data as the holotype. Type material deposition: holotype deposited in the collection of CBSS; paratypes: 2 females and 1 male on slides (No. CLL 3049) deposited in SCA, 1 ex. on slide (No. CLL 3240) deposited in MNHN, Paris, other paratypes deposited in CBSS.

Other material. All caves listed below are in Croatia.

Ogulin–Plaški karst plateau, Trošmarija, Munjasi, Ribnjak canyon, Tonkovića špilja Cave, 1 ex. on slide (No. CLL 1393), 25.xiii.2008, leg. M. Lukić; 1 ex. on slide (No. CLL 2355), 24.vii.2010, leg. M. Lukić; 1 ex. on slide (No. CLL 3127), 24.vii.2011, leg. M. Lukić; 1 ex. on slide (No.CLL 3130), 24.vii.2011, leg. J. Bedek. Tounj, Gornje Dubrave, Gugečka pećina Cave, 1 ex. on slide (No. CLL 1374), 17.vi.2008, leg. M. Kipson. Generalski Stol, Kolići, Jama II kod Kolića Cave, 1 ex. on slide (No. CLL 2130), 2.xii.2009, leg. M. Lukić; 2 ex.on slide (No. CLL 2134), 2.xii.2009, leg. J. Bedek. Trošmarija, Kuštrovka, Kuštrovka Cave, 2 ex. on slides (No. CLL 1424), 27.viii.2008, leg. M. Lukić; 1 ex. on slide (No. CLL 2137), 4.xii.2009, leg. M. Lukić. Bosiljevo, Špehari, Ledenica u Špeharima Cave, 1 ex. on slide (No. CLL 1460), 21.vi.2008, leg. M. Pavlek. Ogulin, Oštarije, Mandelaja Cave, 2 ex. on slides (No. CLL 1837), 10.ix.2009, leg. M. Lukić. Generalski stol, Pećani, Dobra canyon, Pećina pod Pećanima Cave, 1 ex. on slide (No. CLL 1485), 17.vi.2008, leg. M. Lukić. Bosiljevo, Podumol, Dobra canyon, Špilja kod podumolskog mlina Cave, 1 ex. on slide (No. CLL 1469), 24.08.2008, leg. M. Lukić. Tounj, Potok Tounjski, Tamnica Cave, 1 ex. on slide (No. CLL 1959), 12.02.2009, leg. M. Lukić.

Velika Kapela, Drežnica, Drežničko polje, Pražića jaruga Cave, 4 ex. on slides (No. CLL 4371), 16.xiii.2014, leg. M. Lukić. Drežnica, Drežničko polje, Špilja iznad Zečevog ponora Cave, 4 ex. on slides (No. CLL 4329), 17.xiii.2014, leg. M. Lukić. Drežnica, Drežničko polje, Sopača Cave, 3 ex. on slides (No. CLL 4337), 18.xiii.2014, leg. M. Lukić.

Description. Body length 0.9–1.2 mm, habitus typical of the genus. Colour of the body mostly whitish dorsally with reddish dots of pigmentation on head, thorax, abdomen and scx. Integumentary channels observed on head and thorax, connection of epicuticular channels with l.v. on head crossed.

Head ( Figs 19–22 ). Head length and width as 400 and 280 µm, respectively. Dorsal chaetae on head smooth and pointed, frontal chaetae longer (22–30 µm) than those posterior (16–22 µm). Antero-dorsal area with 8+8 chaetae (lateral ones longer than axial) and 2 unpaired chaetae. Antero-lateral area with 5+5 chaetae. Posterodorsal area with 11 chaetae (in postero-axial position 1+1 macrochaetae (28 µm). Postero-lateral area with 4+4 chaetae ( Fig. 19 ). Labrum with 5,5,4 chaetae. Anterior labral chaetae a1 and a2 thick, curved; a2 longer than a1 (25 and 16 µm, respectively). Chaeta a1 medially with 2 strong teeth and finely serrate in distal part, a2 with external edge medially finely serrate. Medial chaetae (m-row) equal (24 µm), smooth, spine-like. Posterior chaetae (p-row) smooth, lateral ones longer than those axial (22 and 18 µm, respectively). Maxillary palp simple ( Fig. 21 ), with 1 enlarged terminal chaeta (40 µm). Basomedian field of labium with 4+4 chaetae ( Fig. 22 ), medial chaetae longer (38 µm) and thicker than others (24 µm); basolateral field with 2+2 chaetae and 1+1 chaetae on tubercle. Ventral side of head with 3+3 smooth postlabial chaetae: 2+2 anterior unequally long, lateral longer than axial (30 and 26 µm, respectively), 1+1 posterior thicker and longer (38 µm) than anterior ones. Mandible strong, with 5 apical teeth. Maxilla as in Fig. 20 .

Thorax and abdomen ( Fig. 23, 24 ). Dorsal side of thorax and abdomen covered with ordinary chaetae, τchaetae, wax rods, swollen S-chaetae and tertiary rods. Dorso-lateral area of Th. II with: 13+13 ordinary chaetae and 2+2 τ-chaetae. Precoxal area of Th. II with 2+2 ordinary chaetae,1+1 τ-chaetae and 1+1 flame-shaped Schaetae (s1). Dorso-lateral area of Th. III-anterior abdomen not seen clearly, with 5+5 chaetae, 2+2 T-shaped Schaetae (s3, s3’), 7+7 wrc (wrc 1–7), 8+8 τ-chaetae and several tertiary rods arranged as in Fig. 23 . Precoxal area of Th. III with 2+2 ordinary chaetae and 1+1 τ-chaetae. Posterior part of the abdomen with at least 19+19 ordinary meso- and macrochaetae (12–17 Μm and 28–30 Μm), 1+1 T-shaped S-chaetae (s2), 1+1 wrc arranged as in Fig. 24 . Their overall number not seen clearly. Abd. VI tergum with 4+4 chaetae (38–40 µm), 1+1 microchaetae (Μ.av) and 1 unpaired posterior mesochaeta of anal valve (av, 11 µm). Abd VI and V sterna cryptic. Ventral anal valves each with 2+2 microchaetae (Μ.av) and 1+1 mesochaetae (av). Abd. VI sternum with 1+1 mesochaetae (9–13 µm) and 6+6 macrochaetae, one more laterally (35–42 µm). Male genital plate with 9+9 microchaetae (6 µm) arranged in circle ( Fig. 25 ). Female genital plate cryptic, with 4+4 chaetae (16 µm) and 1+1 axial microchaetae (8 µm) ( Fig. 26 ). Abd. IV sternum with 4+4 chaetae in one row (26–35 Μm, 1 chaeta placed more laterally). and 1+1 distal chaeta (20 µm). Lateral part of Abd. IV sternum with 1+1 short, sharply pointed and curved neosminthuroid chaetae (13 µm) ( Fig. 25 ).

Appendages. Antennal segments III and IV distinctly separated ( Fig. 27 ). Length of antennae 254 µm, ratio antenna/head = 0.6. Length of antennal segments I, II, III and IV as 15, 60, 77 and 102 µm. Ant. I segment furnished with 3 short chaetae (12 µm). Ant. II with 1 medial chaeta and 5 apical chaetae arranged in a whorl. Ant. III with 14 ordinary chaetae in four whorls (distribution from base to apex: 2, 3, 2, 7 chaetae); 5 apical S-chaetae (S1–S5), S1 and S4 long and tubular (46 µm each), S2 and S3 short and tubular (22 µm), S5 short and flameshaped (8 µm). Ant. IV segment with 17 ordinary chaetae, whorls unclear; 12 S-chaetae with round apex, 10 of them long (25–38 µm), Sx shorter and basally thick (18 µm), Sy thicker than other S-chaetae (32 µm); 2 rod-like curved chaetae in apical (a) and subapical position (sa) and subapical organite Or with two filaments (10 µm). Complete chaetotaxy of antenna provided in Table 2 . Chaetae numbers of legs I–III (Figs 29–31): scx I: 1, 1, 3; scx II: 1, 1, 1; coxae: 1, 1, 2; trochantera: 4, 3, 4; femora: 10, 10, 10 and tibiotarsi: 15, 16, 17. Thin meso- or microchaetae in following numbers on leg I: coxa with 1, trochanter with 3, femur with 2; on leg II: trochanter with 2; on leg III: trochanter with 2, femur with 1. For complete chaetotaxy of legs see Table 3 . Tibiotarsal tenent chaeta pointed. Unguis narrow and extremely elongated, both unguis and unguiculus unequally long in leg I, II and III: unguis 83, 78 and 59 µm, respectively, unguiculus 40, 40 and 43 µm, respectively. Ratio unguis length vs. tibiotarsus length on leg I–III respectively as 0.67, 0.72, 0.71. Ratio unguis length vs. pretarsus width on leg I–III respectively as 4, 3.54, 3.27. Main lamella of unguis furnished with 2 long proximal lamellae in external position la and lp and 1 median lamella Bp. Unguiculus untoothed without apical filament, with basal tubercule. Tubus ventralis with 2+2 distal chaetae and posterior lobe. Retinaculum with 3+3 teeth, chaeta on corpus absent. Furca well developed ( Fig. 28 ), length of manubrium, dens (dp and dd) and mucro: 98, 39, 189 and 155 µm, respectively. Manubrium posteriorly with 4+4 chaetae, lateral (distal 17 µm, proximal 22 µm) shorter than axial (30 µm). Dens in proximal part (dp) with 2+2 posterior chaetae, lateral (34 µm) shorter than axial (43 µm); distal part (dd) with 1 basal postero-external spine (E3), 2 median spines (postero-external E2 and postero-internal J2), 5 apical spines (anterior A1, lateral AE1, AJ1, postero-external E1 and postero-internal J1) and 1 apical posterior chaeta (P1, 20 µm). Mucro with posterior lamellae rather smooth and with irregularities, tip of mucro undivided, rounded.

Sensory fields ( Fig. 19 , 23, 24 , 30, 31). 6+6 s.f. placed in depressions each with secretory rod (13–15 µm), i.e. blunt, straight chaeta with basal part inserted in the cuticle and placed in upper margin of the field. The fields have following arrangement: (a) anterior and posterior field on head (s.f. 1, 2; 25 x 15 µm) each with secretory rod and 1 internal chaeta (on anterior field 32 µm, on posterior one 25 µm, respectively); (b) large thoracal field (s.f. 3; 65 x 75 µm) with secretory rod, 3 internal spines arranged in triangle (8 µm), 2 marginal chaetae (26 µm) and 1 strong macrochaeta (42 µm) on the lateral edge of the s.f.; axial edge of s.f. with 2 mesochaetae (14 µm) and 3 spine-like chaetae (26 µm); anteriorly with 4 lanceolate spines (axial shorter than lateral, 25–36 µm); (c) abdominal field (s.f. 6; 30 x 25 µm) with secretory rod, 1 curved internal spine (8 µm), 2 marginal chaetae (1 internal, 1 external; 12 µm and 25 µm respectively) and T-shaped S-chaetae (s2); (d) fields in the precoxal area of Th. II and III (s.f. 4, 5; 25 x 20 µm) each with secretory rod, 2 curved spines (7 µm). Both s.f. with 2 marginal external chaetae (23 µm, respectively 35 µm).

Both sexes known. Males are smaller than females, the only other difference between sexes is in shape and chaetotaxy of genital area (about 18 microchaetae in males vs. 10 in females).

Etymology. The species is named in honour of geologist and speleologist Damir Lacković (Croatian Natural History Museum, Zagreb; Speleological section PDS Velebit, Zagreb), a passionate caver and discoverer of the first phreatic speleothems in type locality Špilja u kamenolomu Tounj.

Discussion. N. lackovici sp. nov. is closely related to N. klisurensis Kováč & Papáč, 2010 by the presence of stouter lanceolate spines around thoracal s.f. and presence of ordinary meso- and macrochaetae on posterior part of abdomen. The new species clearly differs from other Neelus species by the presence of 4+4 lanceolate anterior spines around thoracal s.f. Moreover, N. lackovici sp. nov. represents the species with the greatest body size of all Neelus congeners coupled with the obvious troglomorphic characters such as much longer chaetae, sensilla and ungua (up to 88 µm on leg I). For other diagnostic characters and length measures see Tables 1 –4. N. lackovici sp. nov. shows strong morphological adaptations to cave environment similar as in many other cave invertebrates of the Balkan Peninsula.

Distribution. N. lackovici sp. nov. is known from altogether 14 caves of the Ogulin–Plaški karst plateau and the western slopes of the Velika Kapela Mt. Relatively small range of this species is likely the result of recently intensive cave fauna inventory in this area, and it is highly probable that the species will be found in other karst areas of the Dinaric Mts.

TABLE 4. Differential characters οf the species οf the genus Neelus Fοlsοm, 1896.

Figures

FIGURES 19 – 22. Neelus lackovici sp. nov.: 19, head, dorsal side with anterior labral chaetae enlarged, sf 1 – 2 — sensory field 1 and 2; 20, maxilla, different views; 21, maxillary outer lobe; 22, ventral side of head with labium.

FIGURES 23 – 24. Neelus lackovici sp. nov.: 23, chaetotaxy and arrangement of sensory fields on thorax and anterior part of abdomen, sf 3 – 5 — sensory field 3 – 5, τ—τ-chaetae; 24, posterior part of abdomen with s 2 sensillum enlarged, sf 6 — sensory field 6, av—anal valve chaetae.

FIGURES 25 – 26. Neelus lackovici sp. nov.: 25, male genital plate, Abd. VI st. — sternum, Abd. IV st. — sternum, nsneosminthuroid chaetae, av—anal valve mesochaetae, Μ. av—microchaetae of anal valves; 26, female genital plate.

FIGURES 27 – 28. Neelus lackovici sp. nov.: 27, antenna, dorsal view (subapical organite of Ant. IV enlarged); 28, furca, posterior view.