Neelus cvitanovici, 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) : 52-61

Neelus cvitanovici sp. nov.

Figs 2, 4–18 , Tables 1 –4

Diagnosis. Cuticle finely granulated, integumentary channels present on head and thorax. Colour mostly whitish sometimes with reddish pigment. Posterior part of abdomen with tertiary rods and 2+2 axial ordinary chaetae. Anterior labral chaetae a1 and a2 thick, curved, a1 medially with 1 strong tooth and serrate in distal part, a2 finely serrate. Ant. I segment with 3 chaetae. Ant. IV segment with 11 S-chaetae with round apex. Unguis apparently elongated. Manubrium with 4+4 posterior chaetae. Mucro with both posterior lamellae serrated, tip of mucro undivided, rounded.

Type material. Holotype: female on slide (No. CLL 4488), Croatia, Otočac, Donji Kosinj, Lipovo polje, Markov ponor Cave (coordinates WGS84 N44.76541° E15.17680°, alt. 500 m.), 21.viii.2011, leg. J. Bedek. Paratypes: 3 females, 1 male and 1 juvenile on slides (No. CLL 3247), the same data as the holotype; 3 females on slides (No. CLL 3262), 20.viii.2011, leg. J. Bedek; 2 females on slides (No. CLL 3240), 19.x.2011, leg. M. Lukić. Type material deposition: holotype deposited in the collection of CBSS; paratypes: 2 ex. on slides (No. CLL 3240) deposited in MNHN and 3 females and 1 juvenile on slides (No. CLL 3247) deposited in SCA; other paratypes deposited in CBSS.

Other material. All caves listed below are in Croatia.

Lički Osik, Ostrvica, Ostrvička špilja Cave, 1 ex.—female on slide (No. 11–14), collection from surface of water pool, 14.v.2014, leg. V. Papáč.

Ličko Lešće, Pećina, Pećina Cave, 4 ex. on slides (No. CLL 3068), 24.vi.2011, leg. M. Lukić.

Gračac, Kesići, Donja Cerovačka špilja Cave, 1 ex.—female on slide (No. 10–14), collection from surface of water pool, 14.v.2014, leg. V. Papáč.

Starigrad Paklenica, Seline, Markova špilja Cave, 3 ex.—females on slides (No. CLL 3999), 19.xii.2012, leg. M. Lukić.

Velebit, Starigrad Paklenica, Velika Paklenica, Manita peć Cave, 1 ex. on slide (No. CLL 3881), 23.x.2012, leg. M. Lukić; 4 ex. on slides (No. CLL 3888), 25.vii.2012, leg. M. Lukić; 1 ex. on slide (No. CLL 3914), 23.x.2012, leg. M. Lukić; 3 ex. on slides (No. CLL 3924), 20.xii.2012, leg. M. Lukić; 2 ex. on slides (No. CLL 3939), 23.x.2012, leg. M. Lukić; 1 ex. on slide (No. CLL 3952), 20.iv.2013, leg. T. Dražina.

Obrovac, Golubić, Krnjeza canyon, Bundalova pećina Cave, 1 ex. on slide (No. CLL 3498), 3.v.2010, leg. D. Hmura. Muškovci, Zrmanja canyon, Čavle Cave, 1 ex. on slide (No. CLL 3483), 2.x.2010, leg. M. Hodžić. Ogari, Zrmanja canyon, Vratolomka Cave, 1 ex. on slide (No. CLL 3463), 2.x.2010, leg. A. Ćukušić.

Description. Body length 0.7–1 mm, habitus typical of the genus. Colour of the body mostly whitish, sometimes with reddish pigment. Cuticle finely granulated, integumentary channels observed on head and thorax, connection of epicuticular channels with l.v. on head crossed ( Fig. 7 ).

Head ( Figs 4–7 ). Head length and width as 280 and 245 µm, respectively. Antero-dorsal area with 9+9 ordinary chaetae (lateral ones longer than axial, 18–20 and 12–16 Μm, respectively) and 2 unpaired chaetae. Antero-lateral area with 4+4 chaetae (18 µm). Postero-dorsal area with 10+10 chaetae. Postero-lateral area with 3+3 chaetae ( Fig. 4 ). Labrum with 5,5,4 chaetae. Anterior chaetae a1 and a2 thick, curved, a2 (20 µm) longer than a1 (13 µm); chaeta a1 medially with 1 strong tooth and finely serrate in distal half; a2 with external edge finely serrate. Medial chaetae (m-row) equal (16 µm), smooth, spine-like. Posterior chaetae (p-row) smooth, lateral longer than axial (15 and 13 µm, respectively). Maxillary palp simple, with 1 enlarged terminal (24 µm), 1 basal (15 µm) and 1 sublobal chaeta ( Fig. 6 ). Basomedian field of labium with 4+4 chaetae ( Fig. 7 ), medial ones longer (20 µm) than others (13–15 µm); basolateral field with 2+2 chaetae and 1+1 chaetae on tubercle ( Fig. 7 ). Ventral side of head with 3+3 smooth postlabial chaetae ( Fig. 7 ); 2+2 anterior chaetae unequal: lateral ones shorter (18 µm), axial longer and slightly curved (20 µm); posterior 1+1 chaetae thickened and curved (20 µm). Mandible with 5 asymmetrical apical teeth. Maxilla as in Fig. 5 .

Thorax and abdomen ( Figs 8 and 10 ). Dorsal side of thorax and abdomen covered with ordinary chaetae, τchaetae, wax rods and swollen S-chaetae of different size (4–6, 12 and 15–18 Μm). Dorso-lateral area of Th. II with 12+12 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 S-chaetae s1. Dorso-lateral area of Th. III-anterior abdomen not seen clearly, with 7+7 ordinary chaetae, 2+2 S-chaetae (s3, s3’), 7+7 wrc (wrc 1–7), 8+8 τ-chaetae and several tertiary rods. Precoxal area of Th. III with 2+2 ordinary chaetae and 1+1 τ-chaetae. Posterior part of the abdomen with 7+7 ordinary chaetae (12–18 Μm), 1+1 S-chaetae (s2), 1+1 wrc and numerous tertiary rods of different length (4–6 Μm) and width arranged as in Fig. 10 ; their overall number not seen clearly. Longer tertiary rods present mostly on posterior part of abdomen and smaller ones on dorso-lateral area of Th. III. Abd. tergum VI with 4+4 chaetae (18–23 µm), 1+1 microchaetae (Μ.av) and 1 unpaired posterior mesochaeta of anal valve (av, 8 µm). Abd. V–VI sterna cryptic. Ventral anal valves each with 2+2 microchaetae (Μ.av) and 1+1 mesochaetae (av). Abd. VI sternum with 1+1 mesochaetae (8–10 µm) and 6+6 macrochaetae, one of them placed more laterally (25–35 µm). Female genital plate ( Fig. 11 ) with 4+4 chaetae (12–16 µm) and 1+1 axial microchaetae. Chaetae of male genital plate arranged in circle, their overall number difficult to observe. Abd. IV sternum with 4+4 chaetae in one row (18 Μm, 1 chaeta placed more laterally) and 1+1 distal chaetae (12 µm). Lateral part of Abd. IV sternum with 1+1 short, sharply pointed and curved neosminthuroid chaetae (8 µm) ( Fig. 11 ).

Appendages. Antennal segments III and IV distinctly separated ( Fig. 13 ). Length of antennae 140 µm, ratio antenna/head = 0.5; length of antennal segments I, II, III and IV as 15, 32, 38 and 55 µm. Ant. I segment furnished with 3 short chaetae (10 µm). Ant. II segment with 1 medial chaeta and 5 apical chaetae arranged in a whorl. Ant. III with 13 ordinary chaetae in three whorls (distribution from base to apex: 2, 4, 7 chaetae); five apical S-chaetae (S1–S5), S1 and S4 long and tubular (31 µm each), S2 and S3 short and tubular (16 µm), S5 short and flameshaped (5 µm). Ant. IV segment with 16 ordinary chaetae, whorls unclear; 11 S-chaetae with round apex, 9 of them long (up to 30 µm), Sx shorter and basally thick (11 µm), Sy thicker than other S-chaetae (25 µm); two rod-like curved chaetae in apical (a) and sub-apical position (sa) and subapical organite Or with two filaments (6 µm). Complete chaetotaxy of antenna provided in Table 2 . Chaetae numbers of legs I–III ( Figs 16–18 ): scx I: 1, 1, 3; scx II: 1, 1, 1; coxae: 1, 1, 2; trochantera: 4, 3, 3; femora: 9, 10, 10 and tibiotarsi: 16, 15, 15. Thin meso- or microchaetae in following numbers on leg I: coxa with 1, trochanter with 2, femur with 1; on leg II: trochanter with 1, femur with 1; on leg III: trochanter with 1, femur with 1. For complete chaetotaxy of legs see Table 3 . Tibiotarsal tenent chaeta straight and pointed (18 µm). Unguis narrow and elongated, both unguis and unguiculus unequally long in leg I, II and III: unguis 45, 40 and 33 µm, respectively, unguiculus 20, 20 and 22 µm, respectively. Ratio unguis length vs. tibiotarsus length on leg I–III respectively as 0.58, 0.63, 0.54. Ratio unguis length vs. pretarsus width on leg I–III respectively as 3.75, 3.3, 2.75. 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 broad basal tubercle. Tubus ventralis with 2+2 distal chaetae and posterior lobe ( Fig. 12 ).

Retinaculum with 3+3 teeth, chaeta on corpus absent ( Fig.14 ). Furca well developed ( Fig. 15 ), length of manubrium, dens (dp and dd) and mucro: 68, 35, 95 and 80 µm, respectively. Manubrium posteriorly with 4+4 chaetae, lateral shorter (10 µm) than axial (15 µm). Dens in proximal part (dp) with 2+2 posterior chaetae, lateral (8 µm) shorter than axial (14 µm); distal part (dd) with a basal postero-external spine (E3), two median spines (postero-external E2 and postero-internal J2), 5 apical spines (lateral AE1, AJ1, anterior A1, postero-external E1 and postero-internal J1) and 1 apical posterior chaeta (P1,15 µm). Mucro with serrated posterior lamellae and rounded tip, 9 Μm wide in its middle part.

Sensory fields ( Figs 4 , 8, 9 , 17 and 18 ). 6+6 s.f. placed in depressions each with secretory rod (7–8 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; 20 x 15 µm) each with secretory rod and 1 internal chaeta (on anterior field 21 µm, on posterior one 17 µm, respectively); (b) thoracal field (s.f. 3; 55 x 30 µm) with secretory rod, 3 curved internal spines (13 µm) arranged in triangle, 3+3 external marginal chaetae (12 µm) and 1 unpaired chaeta (6 µm) above secretory rod and 3 marginal external chaetae below the field (15–20 µm); (c) abdominal field (s.f. 6; 30 x 25 µm) with secretory rod, 1 curved internal spine (7 µm), 2 marginal chaetae (1 internal, 1 external; 12 µm and 14 µm respectively) and S-chaetae (s2); (d) fields in the precoxal area of Th. II and III (s.f. 4, 5; 20 x 15 µm) each with secretory rod, 2 curved spines (6 µm). Both s.f. with 2 marginal external chaetae (10 µm, respectively 17 and 24 µm).

Both sexes known. Males and females differ only in shape and chaetotaxy of genital area.

Variability. In specimens from caves Markova špilja (Paklenica), Ostrvička špilja and Donja Cerovačka špilja tertiary rods take place of 2+2 ordinary chaetae on posterior part of abdomen ( Fig. 8, 10 ).

Etymology. The new species is named in honour of friend, speleologist and passionate collector of cave fauna, Hrvoje Cvitanović, a member of speleological club “Ursus spelaeus” (Karlovac) and CBSS.

Discussion. N. cvitanovici sp. nov. clearly differs from N. koseli Kováč & Papáč, 2010 by different chaetotaxy of hind abdomen (ordinary chaetae and tertiary rods vs. tertiary rods only); and shape of labral chaetae of a-row (a1 forked, medially with strong tooth vs. a1 serrated). For other diagnostic characters and length measures see Tables 1 –4.

Distribution. N. cvitanovici is known from nine caves, most of them situated at the foothills of the Velebit Mts ( Fig. 1 ). Despite the relatively great distribution range among troglobiotic Neelus species in Croatia, it has been recorded in few caves, probably overlooked by biospeleologist in spite of the systematic biospeleological research in the Velebit Mts and Lika region during the last period. The occurrence of this species in other caves of the Velebit Mts is thus highly probable.

Figures

FIGURE 1. Distribution map of the genus Neelus showing all records in Croatian caves, and type locality of N. klisurensis in Kosovo.

FIGURES 4 – 7. Neelus cvitanovici sp. nov.: 4, head, dorsal side, anterior labral row enlarged, sf 1 – 2 — sensory field 1 and 2; 5, maxilla, different views; 6, maxillary outer lobe; 7, ventral side of head with labium and connection of integumentary channels with linea ventralis.

FIGURES 8 – 12. Neelus cvitanovici sp. nov.: 8, chaetotaxy and arrangement of sensory fields on on thorax and abdomen, specimen from Markov ponor cave, sf 4 – 6 — sensory field 4 – 6, ns—neosminthuroid chaetae, τ— τ-chaetae, * indicates variability in type of chaetae; 9, thoracal sensory field with τ-chaetae and 2 + 2 axial chaetae above s. f.; 10, posterior part of abdomen, specimen from Markov ponor cave, av—anal valve chaetae, Μ. av—microchaetae of anal valves, * indicates variability in type of chaetae; 11, Abd. IV-VI half-sterna; 12, tubus ventralis, lateral view.

FIGURES 13 – 15. Neelus cvitanovici sp. nov.: 13, antenna, dorsal view (subapical organite of Ant. IV enlarged); 14, retinaculum; 15, furca, posterior view.

FIGURES 16 – 18. Neelus cvitanovici sp. nov.: 16, leg I; 17, leg II; 18, leg III.

Tables

TABLE 1. Lengths (µm, mean in parenthesis) of morphological structures in N. cvitanovici sp. nov. (females) and N. lackovici sp. nov. (male and females separately).

Body part	N. cvitanovici sp. nov.	N. lackovici sp. nov., females	N. lackovici sp. nov., male
Body total	700–1000 (796)	950–1200 (1073)	900
Head width	205–245 (228.6)	240–280 (256.6)	250
Head length	235–280 (256.6)	313–400 (360.6)	313
a1 labrum	10–13 (10.8)	15–16 (15.5)	15
a2 labrum	18–20 (19)	24–25 (24.7)	23
Antenna	128–140 (135.5)	203–254 (227)	195, 193
Ant. I	13–15 (13.8)	14–15 (14.8)	13, 12
Ant. II	28–32 (30.3)	44–60 (51.2)	39, 40
Ant. III	35–40 (38.3)	60–77 (66.2)	58, 57
Ant. IV	52–56 (54)	83–102 (89)	85, 84
Tibiotarsus I length	70–77 (73.8)	110–130 (116)	110
Tibiotarsus II length	53–63 (56.9)	95–108 (101)	87
Tibiotarsus III length	50–61 (54)	80–101 (90.6)	79
Unguis I	38–45 (42.2)	75–88 (79.7)	75
Unguis II	33–40 (36.9)	68–78 (72)	68
Unguis III	28–33 (30.6)	58–72 (60.6)	58
Unguiculus I	17–20 (18.5)	34–47 (39.7)	35
Unguiculus II	18–20 (19.1)	34–40 (37)	34
Unguiculus III	19–22 (20.7)	38–50 (41)	40
Manubrium	50–68 (62.2)	83–113 (97)	88
Dens (proximal part, dp)	30–35 (32.4)	35–45 (39.6)	33
Dens (distal part, dd)	70–95 (81.6)	160–200 (181.4)	145, 145
Mucro	62–80 (71.4)	130–165 (146.6)	125, 125
Mucro width (middle part)	8–10 (9.2)	18–21 (19.6)	18, 19

TABLE 2. Numbers of antennal chaetae in Neelus cvitanovici sp. nov. and N. lackovici sp. nov.

	Neelus cvitanovici sp. nov.	Neelus lackovici sp. nov.
	Chaetae S-chaetae Miscellaneous	Chaetae S-chaetae Miscellaneous
Ant. I	3 0	3 0
Ant. II	6 0	6 0
Ant. III	13 5	14 5
Ant. IV	16 11 1 Or; 1a; 1sa	17 12 1 Or;1a; 1 sa

TABLE 3. Numbers of leg chaetae in Neelus cvitanovici sp. nov. and N. lackovici sp. nov.

	Neelus cvitanovici sp. nov.		Neelus lackovici sp. nov.
	Leg I Leg II	Leg III	Leg I Leg II	Leg III
Subcoxae I	1 1	3	1 1	3
Subcoxae II	1 1	1	1 1	1
Coxae	1 1	2	1 1	2
Trochanter	4 3	3	4 3	4
Femur	9 10	10	10 10	10
Tibiotarsus	16 15	15	15 16	17