Nemastoma bidentatum sneznikensis Novak, Komposch, Slana Novak & Raspotnig, 2021

Novak, Tone, Novak, Ljuba Slana, Kozel, Peter, Schaider, Miriam Gudrun, Komposch, Christian, Lipovšek, Saška, Podlesnik, Jan, Paušič, Igor & Raspotnig, Günther, 2021, Hidden diversity within the Nemastoma bidentatum Roewer, 1914 complex (Opiliones: Nemastomatidae) Part I: Morphological evidence, European Journal of Taxonomy 777, pp. 1-67 : 40-42

Nemastoma bidentatum sneznikensis Novak, Komposch, Slana Novak & Raspotnig ssp. nov.

urn:lsid:zoobank.org:act:7690FA07-5D60-4545-8660-282ADED3F576

Figs 2–3 , 4I , 5I , 6I , 7I , 8I , 9I , 10I , 11I , 12I , 13H ; Table 11

Etymology

The subspecies name ʻ sneznikensis ʼ references Mt. Snežnik, southern Slovenia.

Diagnosis

Short-legged (leg II <6 mm) species of the N. b. complex, with slightly elongated-trapezoidal Ch-Apo, with row of low tubercles on Pa-Fe and with equilateral triangular glans. Rec sem of 18 balloon-like vesicles.

Material examined

Holotype SLOVENIA – VL54 • 1 ♂; Mt. Snežnik; 45.59° N, 14.44° E; 1553 m a.s.l.; 21 Aug. 1998; Ljuba Slana Novak and Tone Novak leg.; deep-humus in Dinaric Pinus mugo scrub in contact with the Dinaric Fagus sylvatica – Abies alba treeline litter sift; PMSL-Opiliones-TN 1494/1998 .

Paratypes SLOVENIA – VL54 • 2 ♂♂, 1 ♀; same collection data as for holotype; PMSL-Opiliones-TN 1494/1998 .

Other material

SLOVENIA – VL54 • 3 ♂♂, 4 ♀♀; Mt. Snežnik ; 20 Jul. 1999; L. Slana Novak and T. Novak leg. (185/1999, rev. 2009); PMSL .

Description

Male (holotype)

BODY. Length 1.81, width 1.18.

CHELICERAE. Ch basal article (without Apo) length 0.53, 2.7 times as long as wide at Ch max width at dorsal hump. Ch-Apo oval-trapezoid, wider distally, without apical pinnacle. Ch-Apo height 0.13, max width 0.13, min width 0.08 (at the base). Secretion field frontally. Distal article length 0.51, max width 0.17, movable finger length 0.22 ( Figs 4I , 6I , 9I ).

PEDIPALPS. Pa-Tr with dorsal margin slightly inclined distally. Pa-Fe slightly club-shaped (Pa-Fe min:max width ~ 1:2.6) with terminal bonce, and 7 irregular granula in distal third. Pa-Pt length:max width ~ 1:4.3. Pa-Ti slender ( Figs 5I , 6I , 10I ). Pa article lengths in Table 12 .

PENIS. Pe length 1.22, base 0.46, glans 0.09, stylus 0.04 ( Figs 7I , 8I ).

LEGS. Pseudoarticle leg-Fe formula I−IV: 0−1−1−2. Tarsomere leg formula I−IV: 9−14−6−8. Leg article lengths in Table 12 .

Female

BODY. Length 2.11, width 1.43.

CHELICERAE. Ch basal article length 0.59, 2.7 times as long as wide at dorsal hump, with low-arched dorsal margin in front of indentation and straight ventral margin ( Fig. 13H ). Distal article length 0.66, max width 0.20, movable finger length 0.30.

PEDIPALPS. Pa-Tr low, with roof-like broken dorsal margin, highest in the first two fifths. Pa-Fe distally with low ventral hump, Pa-Pt, Pa-Ti and Pa-Ta elongated ( Fig. 13H ). Pa article lengths in Table 12 .

OVIPOSITOR. Ovipositor length 0.62, Rec sem of 18 balloon-like vesicles ( Fig. 11I ).

LEGS. Leg article lengths in Table 12 .

Remarks

Regarding external morphology, N. b. sneznikensis ssp. nov. is very similar to N. relictum , including the habitus, the similarly shaped Pa and relatively short legs. No individuals belonging to the subspecies were found in the last decade. See remarks on taxa of Nemastoma on Mt. Snežnik under N. b. gruberi ssp. nov.

Distribution

Despite over 30 collections, this taxon has been recorded only in a limited area on Mt. Snežnik. Endemic to Mt. Snežnik, southern Slovenia. Type locality: Mt. Snežnik (45.59° N, 14.44° E, 1553 m a.s.l.), Slovenia.

Ecology

Nemastoma b. sneznikensis ssp. nov. is a psychrophilous subspecies. To date it has been recorded only in a cold, well-drained, deep mull humus Dinaric Pinus mugo scrub in contact with the Dinaric Fagus sylvatica – Abies alba treeline on calcareous soils. Likely, it inhabits other cold habitats, like scree and stone heap edges in contact with humus accumulations, as is known for N. relictum ( Komposch 1999; Komposch & Gruber 2004), and perhaps a humus-rich shallow subterranean habitat (SSH), i.e., Milieu Souterrain Superficiel (MSS) ( Mammola et al. 2016; Halse 2018). Since this habitat is restricted to an area of less than 1 km 2 on Mt. Snežnik, this subspecies is considered highly endangered. Phenology: probably eurychronous.

Hybrids among the subspecies of Nemastoma bidentatum

Remarks

In Austria, a few localities are known where N. b. bidentatum lives in syntopy with N. relictum ( Gruber & Martens 1968; Martens 1978; in both papers sub N. b. relictum ), and with N. b. sparsum ( Komposch & Gruber 2004; Komposch 2009). However, individuals of these three taxa do not interbreed and have been considered as potential species ( Gruber & Martens 1968; Martens 1978; Komposch & Gruber 2004; Komposch 2009). In Slovenia, N. b. schmidti ssp. nov., with its central geographic position, interbreeds with all other adjacent subspecies: N. b. bidentatum in the North, and N. b. martensi ssp. nov., N. b. sneznikensis ssp. nov., N. b. gruberi ssp. nov. and N. b. sparsum from the Southwest to the Northeast of the country. Besides, N. b. gruberi ssp. nov. interbreed with N. b. martensi ssp. nov., and with N. b. sparsum. In Bosnia, N. pluridentatum stat. nov. has not been found; consequently, the genitalia have not been examined. Despite this, major differences from all the other known taxa within the N. b. complex allow it to be considered a separate species. This is because interbreeding of N. pluridentatum stat. nov., which might be a subalpine species, with the montane N. kozari sp. nov. from the same mountain is quite unlikely, given their great dissimilarity. However, data on taxa of Nemastoma in Bosnia and Herzegovina are nearly completely missing, allowing no further conclusions.

Although being morphologically variable, hybrids possess larger Ch-Apo than pure subspecies and are well distinguishable from these. In interbreeding subspecies, hybrids between the two subspecies frequently occur syntopically with individuals belonging to pure subspecies. Consequently, such a collection consists of either one or two pure subspecies and a series of hybrids with varying Ch-Apo shapes.

An overview of interbreeding relations among the taxa of the N. b. complex is presented in Table 13. In Slovenia, N. b. bidentatum and N. b. sparsum do not interbreed, since the areas are several tens of kilometres distant from each other. In contrast, we have found hybrids between all the adjacent subspecies ( Fig. 3 ), except N. b. gruberi ssp. nov. × N. b. schmidti ssp. nov. × N. b. sparsum, which is expected in the meeting area of the three taxa. Besides, data on hybridization of N. b. sneznikensis ssp. nov. are too scarce to be properly evaluated in full. The zone of hybridization between N. b. schmidti ssp. nov. and N. b. sparsum is the widest, measuring up to 100 km in north-eastern Slovenia, while these zones are narrow to virtually non-identifiable among the others, and hybrids are accordingly scarce. Hybrids N. b. gruberi ssp. nov. × N. b. schmidti ssp. nov. were found in a zone up to 10 km wide, while N. b. martensi ssp. nov. × N. b. schmidti ssp. nov. and N. b. gruberi ssp. nov. × N. b. martensi ssp. nov. are limited to zones a few kilometers wide. In Slovenia, there are no hybrids between allopatric N. b. martensi ssp. nov. and N. b. sparsum, while these are expected in Croatia.

Hybridization patterns were not simple clines in the transition zones between two subspecies. Instead, in some cases, morphologically various hybrids between the neighboring subspecies, sharing various ratios of the hybridizing subspecies characters (cf. Gruber & Martens 1968; Martens 1978), appeared scattered across the whole width of the transition zone. In some places in the hybridization zone, individuals of both subspecies, together with hybrids of various intermittent stages, occurred syntopically.

Figures

Fig. 2. The complete distributional area of the Nemastoma bidentatum Roewer, 1914 complex, according to Gruber & Martens (1968), Martens (2006), Schönhofer & Holle (2007) and own data, with marked positions of the type localities of the taxa.

Fig. 3. Distributional areas of six subspecies (circles) and hybrids (triangles, squares) within the Nemastoma bidentatum Roewer, 1914 in Slovenia and adjacent regions. Note that many localities overlap on the map.

Fig. 4. Nemastoma bidentatum Roewer, 1914 complex, ♂♂. Ch basal articles (medial, lateral views).

Fig. 5. Nemastoma bidentatum Roewer, 1914 complex, ♂♂. Pa (medial view).

Fig. 6. Nemastoma bidentatum Roewer, 1914 complex, ♂♂. Synchroscopic images of the male Ch basal article and Pa-Fe (medial views, except G, right figure, which is in dorso-medial view).

Fig. 7. Nemastoma bidentatum Roewer, 1914 complex. Penes (lateral view). Note: The penis of N. pluridentatum (Hadži, 1973) stat. nov. is unknown.

Fig. 8. Nemastoma bidentatum Roewer, 1914 complex. Glans (dorsal and lateral views). Note: The penis of N. pluridentatum (Hadži, 1973) stat. nov. is unknown.

Fig. 9. Nemastoma bidentatum Roewer, 1914 complex, ♂♂. Variation of the Ch basal article (medial view) in species, subspecies and hybrids.

Fig. 10. Nemastoma bidentatum Roewer, 1914 complex, ♂♂. Variation of the Pa-Fe (A–B first image, C, D–E first image, F–G first image; H–J, L–M right, N–O: lateral view; the others in dorso-medial view to show the armament).

Fig. 11. Nemastoma bidentatum Roewer, 1914 complex, ♀♀; Rec sem (lateral view, right portion, except F left figure, which is in dorsal view). A. The frame encloses the ovipositor portion with Rec sem. Note: Female N. pluridentatum (Hadži, 1973) stat. nov. is unknown.

Fig. 12. Nemastoma bidentatum Roewer, 1914 complex, ♂♂. From left to right: Ch basal article (medial, lateral views), Pa (medial view) and Pe tip (dorsal, lateral views). Arrows indicate the most identifying characters. Note: Pe of N. pluridentatum (Hadži, 1973) stat. nov. is unknown.

Fig. 13. Nemastoma bidentatum Roewer, 1914 complex, ♀♀. From left to right: Silhouettes of the Ch basal article, Pa (both medial view) and Rec sem. Arrows indicate the most identifying characters. Note: female N. pluridentatum (Hadži, 1973) stat. nov. is unknown.