Thinobius crypticola, Janák & Makranczy, 2016

Janák, Jiří & Makranczy, György, 2016, Description of a blind and flightless species of Thinobius from South Africa (Coleoptera: Staphylinidae: Oxytelinae), Acta Entomologica Musei Nationalis Pragae 56 (1), pp. 203-210 : 205-210

Thinobius crypticola sp. nov.

( Figs 1–2 , 5–13 )

Type locality. South Africa, Western Cape Province, Ysternek Nature Reserve, Dal van Varings Trail, off Highway R339, 33°54.8′S, 23°8.7′E ( Fig. 3 ).

Type material. HOLOTYPE: J, ‘ South Africa, Western Cape, Ysternek N.R. [Nature Reserve], Dal van Varings Tr. [ail], off Hwy R 339; 33°54.8’S 23°8.7’E; 7.ii.2014, J. Janák lgt. \ Berlese extraction, leaf & log litter, sifting \ Holotypus Thinobius crypticola sp. nov., J. Janák & Gy. Makranczy det. 2015’ ( TMSA). PARATYPES (76 specimens): 19 JJ 15 ♀♀: same data as holotype (1 J 1 ♀ in TMSA, 1 J 1 ♀ in NMPC, 1 J 1 ♀ NHMW, 1 J 1 ♀ in HNHM, 15 JJ 11 ♀♀ in JJRC) {19.4 kg }; 2 JJ 2 ♀♀: ‘ South Africa, Western Cape, Diepwalle S.F. [ State Forest ] (14 km ENE Knysna) ; 33°57.2´S 23°9.5´E; 7.ii.2014, J. Janák lgt., Berlese extraction, leaf & log litter, sifting’ ( JJRC) {16.7 kg, Fig. 4 }; 6 JJ 4 ♀♀: ‘ South Africa, Western Cape, Diepwalle S. F., Kom Se Pad , Red Elephant Tr. [Trail] ; 33°56.0´S 23°8.0´E; 9.ii.2014, J. Janák lgt., Berlese extraction, leaf & log litter, sifting’ (1 J TMSA, 5 JJ 4 ♀♀ JJRC) {13.4 kg }; 6 JJ 5 ♀♀: ‘ South Africa, Western Cape, Diepwalle S.F. [State Forest], Kom Se Pad , 1.7 km W Hwy [Highway] R339 ; 33°56.7´S 23°8.0´E; 9.ii.2014, J. Janák lgt., Berlese extraction, leaf & log litter, sifting’ (1 J 1 ♀ TMSA, 5 JJ 4 ♀♀ JJRC) {5.6 kg }; 4 JJ 4 ♀♀: ‘ South Africa: Western Cape: Ysternek N.R., Dal van Varings Tr., off Hwy R 339, 650m, 33°54.8’S, 23°08.7’E, 30.i.2004, tall Afromontane forest w/abundant tree ferns ; FMHD #2004-022, berl., leaf & log litter, Newton, Thayer et al. 1080 Field Museum Nat. Hist. ’ (all FMNH, in 70% ethanol) {8.2 kg }; 5 JJ 1 ♀ (+ 1 larva): ‘ South Africa: Western Cape: Diepwalle S.F., Kom Se Pad, 1.7 km W Hwy R 339, 420m, 33°56.7’S, 23°08’E, 30.i.2004, tall Afromontane forest ; FMHD #2004-024, berl., leaf & log litter, Newton, Solodovnikov et al. 1081 Field Museum Nat. Hist. ’ (all FMNH, in 70% ethanol) {10.0 kg }; 1 J 2 ♀♀: ‘ South Africa: Western Cape: Gouna S.F., Kom Se Pad, 6.2 km W Hwy R 339, 440m, 33°56.7’S, 23°05.6’E, 31.i.2004, Afromontane forest w/ground ferns, few lianas ; FMHD #2004-030, berl., leaf & log litter, Newton 1083 Field Museum Nat. Hist. ’ (all FMNH, in 70% ethanol) {3.0 kg }.

Description. Measurements (in mm, n = 10): HW = 0.175 (0.165 –0.185); PW = 0.180 (0.170 – 0.185); EW = 0.170 (0.160 –0.180); AW = 0.210 (0.190 –0.230); HL = 0.160 (0.150 –0.170); PL = 0.145 (0.135 –0.150); SL = 0.130 (0.120 –0.135); SC = 0.115 (0.105 –0.120); FB = 0.440 (0.420 –0.460); BL = 1.110 (0.955 –1.235). Body ( Fig. 1 ) straw yellow, moderately lustrous, although microsculpture weak (inconspicuous on forebody). Forebody sparsely punctate, punctures moderately small, interspaces on average 4–5× puncture diameters. Body rather translucent, area between supraantennal tubercles (around epistomal suture) darker, pronotal marginal bead laterally and posteriorly marked as thin darker line. A few thicker setae dark brown, finer setae match overall body colour.Apex of antennomere II with slightly darker rim.

Head slightly transverse, eyes absent, sides of head gently curved. Neck not separated by groove, although sides of head constricted before it and narrowly rounded there. Disc of head gently convex, with feeble coriaceous microsculpture (with isodiametric cells of varying sizes), at obscure demarcation line of neck microsculpture turning transverse; supraantennal tubercles slightly elevated. Maxillary palps ( Fig. 6 ) with penultimate segment fusiform, last segment not acicular but asymmetrical, bulbous at base. Antennae ( Fig. 5 ) rather short, antennomeres I, II and XI quite stout, mid antennomeres strongly transverse; antennomere V significantly smaller than neighbouring antennomeres, latter may appear somewhat asymmetrical from a certain viewpoint. Antennomeres IX–XI with modified setae (remarkably thicker, less point- ed), similar to those in other endogean staphylinids like leptotyphlines, antennomere VII also occasionally with few small and short modified setae.

Pronotum transverse, insignificantly wider than head, corners rounded, posteriorly more broadly than anteriorly. Arched sides somewhat constricted towards base, although widest point still around or little behind middle. Pronotal marginal bead very thin, anteriorly mostly missing. Disc with similar microsculpture as vertex, in middle with two parallel longitudinal impressions (leaving free anterior fourth). Scutellum as in Fig. 7 , sculpture rather reduced, short setae only in postero-lateral and lateral parts. Elytra combined significantly broader than long, dilated towards apex, together less wide than pronotum, anterior margin at sutural corners slightly concave. Humeri poorly developed, posterior elytral corners broadly round- ed, disc mostly convex, along suture with marginal bead. Hind wings absent. Legs short and rather stout, tibiae spindle-shaped. Tarsi two segmented as in other Thinobius , basal article with setae modified as tarsal lobes.

Abdomen weakly fusiform, sides more or less straight and parallel, widest around middle and slightly wider than elytra. Tergites with narrow laterosclerites, basal ridges and basolateral ridges separated and running parallel in the middle, basolateral ridges marked in dark brown colour medially. Surface with strongly transverse coriaceous microsculpture, apical margin of tergite VII with thin palisade fringe consisting of short and somewhat sparse setae (not tightly arranged). Primary and secondary sexual characters. Sexes do not differ in external characters except terminalia. Male sternite VIII as in Fig. 8 , tergites IX as in Fig. 9 , sternite IX as in Fig. 10 , tergite X similar in both sexes. Aedeagus as in Fig. 11 . Female modified genital appendages as in Fig. 12 , spermatheca as in Fig. 13 .

Differential diagnosis. The new species bears similarity only to Thinobius korbeli Löbl & Rychlík, 1994 from Slovakia and Hungary ( LÖBL & RYCHLÍK 1994, MAKRANCZY 2008) and T. kuroshio ( Sawada, 1971) from Japan ( GUSAROV & MAKRANCZY 2004) in the absence of eyes and functional wings. The male genitalia of T. crypticola sp. nov. are similar to those of many other Thinobius species. Thinobius kuroshio has much longer antennae with more elongate antennomeres, while T. korbeli also has less transverse mid-antennal segments. In the new species these are conspicuously transverse (approximately twice as broad as long) and maxillary palps are remarkably different from both other blind species: the normally acicular last palpomere is swollen and curved in the middle and the penultimate palpomere is more slender. The two species of the Northern Hemisphere seem to be united by a more swollen penultimate palpomere and an acicular last segment.

Etymology. The species epithet refers to its hidden way of life, the Latin word ‘ crypticola ’ is a noun in apposition.

Distribution and habitat. Only known from South Africa. The type locality is situated in the Ysternek Nature Reserve (currently part of the Knysna Section of Garden Route National Park) at an elevation of about 650 m a.s.l. It is an Afromontane indigenous forest with abundant fern trees. All the other collecting sites are within a 6 km sided triangle, in a rather similar Afromontane forest (with less frequent fern trees); the FMNH localities, in the sequence listed, are roughly from wetter to drier sites with elevations 420–650 m a.s.l. The highest abundance of T. crypticola sp. nov. in sifted material was about two specimens per kg in Dal van Varings Trail (2014, Janák lgt.) and Kom Se Pad, 1.7 km W Hwy R339 (2014, Janák lgt.). As far as habitats are concerned, T. korbeli is more similar to the new species described here, as it was collected 10–40 cm deep in soil in riverine forests.

Larva. In one of the three FMNH samples (collected in 2004) one oxyteline larva was found that almost certainly is conspecific with T. crypticola sp. nov. This larva was identified by A. Newton as Oxytelinae based on agreement with published characterizations of larvae of this subfamily by KASULE (1968) and NEWTON (1982) and general knowledge of larval characteristics of this group, including the presence of two subapical teeth on each mandible giving a ‘trifid’ appearance, a penultimate maxillary palp segment that is shorter than the preceding and ultimate segments, a long looped gut with visible but unidentifiable organic matter, and short pigmented urogomphi that appear one-segmented. It was further attributed to this Thinobius by association with adults in the same microhabitat, the absence of stemmata (unusual in oxyteline larvae, and in agreement with the lack of eyes in adults), and agreement with the only described larva of Thinobius , T. frizzelli Hatch, 1957 (a partial description by KINCAID 1961). In addition, there were no other Oxytelinae in these samples.

The total length (including urogomphi) is 1.25 mm. The rather slender shaped specimen has the head and urogomphi more sclerotized than the rest of the body, the thoracic segments and the middle part appear soft and at least partly dissolved. A possible explanation is that the cuticle of this delicate specimen does not withstand extended storage in ethanol. The same observation was made by the second author with a larva of T. korbeli . This state of preservation ( Fig. 2 ) does not allow a proper description.

Figures

Figs 1–2. Thinobius crypticola sp. nov.: 1 – male holotype, dorsal habitus; 2 – suspected larva (maximum width of head capsule 0.16 mm).

Figs 5–13. Thinobius crypticola sp. nov. 5 – antenna; 6 – maxillary palp; 7 – scutellum; 8 – male sternite VIII; 9 – male tergite IX; 10 – male sternite IX; 11 – aedeagus, frontal; 12 – female genital appendage; 13 – spermatheca. Scale bars: 0.075 mm for 11, 13; 0.09 mm for 5–7, 9–10, 12; 0.1 mm for 8.

Figs 3–4. Habitats of Thinobius crypticola sp. nov. 3 – Knysna, Dal van Varings Trail (type locality); 4 – Knysna, Diepwalle State Forest (photos by J. Janák).