Cryptopygus antarcticus Willem, 1902.

A genus of the Cryptopygus complex. Medial s-chaetae in mid-tergal position from Th. II to Abd. III. Number of s-chaetae 4,3/2,2,2,3,5. Foil chaetae at the end of abdomen absent.

Here we follow our simplified characterisation of the genus proposed formerly (Potapov et al. 2017) that is an expanded version of diagnosis of Rusek (2002). The latter diagnosis offers to be within the limits of the definite number of ocelli (6+6), “antarcticus-like” furca and clavate tibiotarsal hairs. We presume a wide variation of the main characters: the mucro may be absent, bidentate or tridentate; the manubrium with or without anterior chaetae; the dens short and smooth to long and crenulated; the ocelli absent to their full set, i.e. 8+8; tenent tibiotarsal hairs clavate or pointed; number of ms-chaetae from 1,0/0,0,0 to 1,1/1,1,1; maxillary outer lobe with changeable shape of palp and number of sublobal hairs. In our view, the splitting of Cryptopygus to groups, subgenera or genera will be probably necessary, but calls for preliminary morphological revisions and expanded molecular data of known species.

Species closely related to C. antarcticus, i.e., belonging to Cryptopygus sensu Rusek, have also been found in this study in South Africa (see below) but their status remain unsolved because of the taxonomic and molecular complexity of this group (Deharveng, 1981; Stevens et al. 2006; McGaughran et al. 2010).

Holotype and thirteen paratypes: South Africa • Western Cape, Cederberg Wilderness Area, Wolfberg Crags; 32.471507S, 19.278397E; 19 Feb 2011; C. Janion-Scheepers leg.; litter, Tullgren extraction; RSA11_CED002, deposited at SAMC • six paratypes on four slides and seven paratypes in ethanol; same locality • sixteen paratypes; Western Cape, Cederberg Wilderness Area; 32.310167S, 19.175183E; Oct. 2008; C. Janion-Scheepers leg.; pitfall trap; RSA08_CED001. Four paratypes deposited in ethanol at SAMC, five paratypes on three slides deposited at SMNG, seven paratypes on three slides at MSPU.

South Africa • Western Cape, Mont Rochelle Nature Reserve, Franschoek; 33.902967S, 19.158950E; 06 Oct. 2008; C. Janion-Scheepers leg.; Erica site with Erica-Protea (Ericaceae and Protacea) mixed litter, litter trap; MR644, MR648 • Western Cape, Kogelberg Nature Reserve; 34.328083S, 18.962250E; 29 Aug. 2008; C. Janion-Scheepers leg.; Erica Site, Litter trap (K467), with Galenia litter.

With a globular retractile bulb on Ant. IV. Organite on Ant. IV chili-like. 6+6 ocelli. Maxillary palp simple. Two sublobal hairs. Anterior side of manubrium without chaetae. Tenaculum with one chaeta.

Body size 0.7–0.9 mm, habitus as in Figs 1, 2. Body with rather regular blue pigmentation, slender. Abd. V well separated from Abd. IV and fused with Abd. VI (Fig. 4). Cuticle “smooth”, with orthogonal primary granulation. Ocelli 6+6 arranged in anterior and posterior groups (Fig. 8), three in each. PAO more than twice as long as ocellus, 0.6–0.7 as long as width of Ant. I and 1.0–1.3 as long as inner unguis length. Maxillary head with unmodified lamellae. Maxillary outer lobe with two sublobal hairs, maxillary palp simple. Labral formula as 2/5,5,4, edge of labrum not reduced (Fig. 7). Labium with five usual papillae (A–E) and labial formula A1B3C0D4E6, guard chaetae e7 and b4 absent, three proximal and four basomedian chaetae. Ventral side of head with 4+4 chaetae. Ant. I with two ventral s-chaetae (s) and three small bms, two dorsal and one ventral, Ant. II with three bms and one latero-distal s, Ant. III with one bms and five distal s (including one lateral), without additional s-chaetae. S-chaetae on Ant. IV weakly differentiated. Organite long, of chili-like shape, set apart from subapical micro s-chaeta (Figs 9, 10). A globular retractile bulb embedded at tip of antennae, near pin-chaeta (Figs 9, 10).

Common chaetae often slightly serrated at the posterior part of Abd. V. S-formula as 4,3/2,2,2,3,5 (s), 1,0/1,0,0 (ms) (Fig. 7). Tergal s-chaetae much shorter than common chaetae and well distinguishable (Fig. 4). Medial s-chaetae on Th. II-Abd. III situated in mid-tergal position. On Abd. V, three dorsal s-chaetae (al, accp1, accp2) and two lateral ones slightly shorter (Fig. 6). Macrochaetae smooth and short, 1,1/3,3,3 in number, medial ones on Abd. VI 1.6–2.0 times longer than dens and 2.8–4.1 times longer than mucro. Foil chaetae at the tip of abdomen absent. Axial chaetotaxy as 5–6,4/3,3(4),3–4,4–6. Th. I and II without ventral chaetae, Th. III with 2+2 ventral chaetae (Fig. 1).

Unguis of normal shape, without teeth. Empodial appendage 0.5–0.7 as long as unguis. Tibiotarsi without additional chaetae on Leg I and II (21 chaetae), and with few ones on Leg III (>25), adult males with short thickened spurs on tibiotarsi III (Fig. 11). Tibiotarsal tenent hairs clavate, 1,2,2 on Tibiotarsi 1,2,3. Ventral tube with 3+3 laterodistal and 4–6 posterior chaetae, anteriorly without chaetae (Fig. 12). Tenaculum with 4+4 teeth and one chaeta. Anterior furcal subcoxa with 5–7, posterior one with three chaetae. Anterior side of manubrium without chaetae, posterior side with 4+4 laterobasal and 8–10 chaetae on main part, without lateral chaetae (Figs 13, 14). Dens short, without crenulation, with one rigid and short anterior and three posterior chaetae. Mucro bidentate. Ratio manubrium : dens : mucro = 2.5–4.1 : 1.7–2.2 : 1.

The name is derived from the presence of apical bulb on Ant. IV.

Currently known to occur in the southern part of the Western Cape Province of South Africa, including Kogelberg, Franschoek and the Table Mountain area (Cape Town). All specimens were collected from leaf litter in indigenous vegetation.

The species differs from other representatives of the Cryptopygus complex, if not from all Isotomidae of the Southern Hemisphere, by the presence of a globular bulb at tip of the antennae. The taxonomical value of this character is not fully clear. In the Northern Hemisphere several unrelated genera also possess an apical bulb which is embedded on the tip of the antennae, for example Anurophorus Nicolet, 1842 (most of the species), Sibiracanthella Potapov & Stebaeva, 1994, Tuvia Grinbergs, 1962 and Vertagopus Börner, 1906 (few species). The antennal bulb of C. bulbus sp. nov. is set apart from the apex, which is unlike in the aforementioned taxa. The only exception found was in specimens observed from Orangekloof (Cape Town), where the apical bulb was less developed.

For other differences of the new species from congeners see the Discussion of C. abulbus sp. nov.

Holotype and eighteen paratypes: South Africa • Western Cape, Stellenbosch, Jonkershoek Nature Reserve; 33.986883S, 18.955350E; 30 July 2009; C. Janion-Scheepers leg.; litter trap (J2_32), Holotype and eight paratypes deposited on four slides at SAMC, four paratypes on two slides deposited at SMNG, four paratypes on two slides deposited at MSPU, two paratypes on one slide at MNHN.

Without globular retractile bulb on Ant. IV. Organite on Ant. IV chili-like. 6+6 ocelli. Maxillary palp simple. Two sublobal hairs. Anterior side of manubrium without chaetae. Tenaculum with two chaetae.

Body size 0.6–0.7 mm. Body with regular blue pigmentation, slender (Fig. 3). Abd. V well separated from Abd. IV and fused with Abd. VI (Fig. 15). Cuticle with orthogonal granulation. Ocelli 6+6 arranged as three in anterior and three in posterior group (Fig. 19). PAO more than twice as long as ocellus, 0.6–0.7 as long as width of Ant. I and 0.8–1.1 mm as long as inner unguis length. Maxillary outer lobe with two sublobal hairs, one individual with one sublobal hair on one side was found. Maxillary palp simple. Labral formula as 2/5,5,4. Labium with five usual papillae (A–E, Fig. 16) and labial formula as in C. bulbus sp. nov. Ventral side of head with 4+4 postlabial chaetae. Ant. I with eleven common chaetae, two ventral s-chaetae (s) and three small basal micro s-chaetae (bms), two dorsal and one ventral, Ant. II with three bms and one latero-distal s, Ant. III with one bms and five distal s (including one lateral). S-chaetae on Ant. IV weakly differentiated. Organite long, of chili-like shape, set apart from subapical micro s-chaeta (Figs 17, 18). Tip of antennae without retractile bulb.

Common chaetae slightly (under very high magnification) serrated at the posterior part of abdomen. S-formula as 4,3/2,2,2,3,5 (s), 1,0/1,0,0 (ms) (Figs 5, 15). Tergal s-chaetae much shorter than common chaetae and well distinguishable. Medial s-chaetae on Th. II-Abd. III situated in mid-tergal position. Macrochaetae smooth and short, 1,1/3,3,3 in number, medial ones on Abd. VI 1.6–2.0 times longer than dens and 2.8–4.1 times longer than mucro. Foil chaetae at the tip of abdomen absent. Axial chaetotaxy as 6–8,5/3,3,3,5–6. Th. I and II without chaetae, Th. III with 2+2 ventral chaetae.

Unguis without teeth. Empodial appendage 0.5–0.7 as in C. bulbus sp. nov. Tibiotarsi without additional chaetae on Leg I and II (21 chaetae), and with a few additional ones on Leg III, about 26 chaetae. Tibiotarsal tenent hairs clavate, 1,2,2 on Tibiotarsi 1,2,3. Ventral tube with 3+3 laterodistal and four posterior chaetae, anteriorly without chaetae (Fig. 20). Tenaculum with 4+4 teeth and two chaetae. Anterior furcal subcoxa with 5–7, posterior one with three chaetae. Anterior side of manubrium without chaetae, posterior side with 4+4 laterobasal and 8–9 chaetae on main part, without lateral chaetae. Dens short, without crenulation, with one rigid and short anterior and three posterior chaetae (Figs 21, 22). Mucro bidentate. Ratio manubrium : dens : mucro = 3.3–3.8 : 1.7–2.3 : 1.

The name is derived from the absence of apical bulb on Ant. IV to stress the difference from C. bulbus sp. nov.

Currently known from indigenous vegetation in the Jonkershoek Nature Reserve, Stellenbosch.

Unlike C. bulbus sp. nov., the new species has no antennal bulb. Nevertheless, the two species form a rather well-defined group differing from almost all congeners by a simple maxillary palp, two sublobal hairs, chili-shaped organite on Ant. IV, and the absence of chaetae on the anterior side of the manubrium. Concerning the last character, only C. nivicolus (Salmon, 1965) and C. sverdrupi Lawrence, 1978 also lack this pair of chaetae, which is common to other species of the genus. Both mentioned species are inhabitants of Antarctic polar deserts and can hardly be conspecific to C. abulbus sp. nov. found in dry sites in a subtropical climate. These two Antarctic species are very dark and have two clavate tenent hairs (vs. one in C. abulbus sp. nov.) on tibiotarsi I. In addition, C. nivicolus has no mucro (vs. present in the new species) while C. sverdrupi has very small PAO (more than twice longer than ocellus in C. abulbus sp. nov.). Recently, Gressitacantha terranova Wise, 1967 was moved to Cryptopygus (Greenslade, 2015) adding another Cryptopygus species without anterior chaetae on the manubrium. The differences between C. abulbus sp. nov. and C. terranovus are more numerous than those from C. nivicolus and C. sverdrupi (in furca, arms of abdomen, length of macrochaetae, and others).

Holotype and three paratype: South Africa • Western Cape, Kogelberg Biosphere Reserve; 34.332650S, 18.950900E; 04 Oct. 2011; C. Janion-Scheepers leg.; Afromontane forest, litter/wood, Tullgren-Berlese extraction; RSA11_KOG007. Deposited on two slides at SAMC.

South Africa • Western Cape, Haarwegskloof, Swellendam; 34.335968S, 20.325094E; 18 July 2017; O. Cowan leg. Deposited at MSPU.

1+1 ocelli. PAO very long and slender, with large inner denticles. MS-formula 1,0/0,0,1 (ms). All s-chaetae of Abd. V in one dorsal group. Anterior side of manubrium with 1+1 chaetae. Dens of medium length. Mucro tridentate.

Body size 0.8 mm (only one adult female could be measured). Body mostly white, slender, with rare, scattered pigmentation and a distinct black eyespot (Fig. 23). Abd. V well separated from Abd. IV and fused with Abd. VI (Fig. 31). Cuticle with orthogonal and hexagonal granulation. One rudimentary ocellus, with a concentration of pigmentation. PAO very long and slender (Fig. 27), at least five times as long as ocellus, twice as long as width of Ant. I and 2.8 as long as inner unguis length. PAO constricted, with large “inner denticles”. Maxillary head with unmodified lamellae. Maxillary outer lobe with four sublobal hairs, maxillary palp bifurcate. Labral formula as 4/5,5,4, edge of labrum not reduced. Labium with five usual papillae (A–E), guard chaetae e7 present, three proximal and four basomedian chaetae. Ventral side of head with 4+4 chaetae. Ant. I with two ventral s-chaetae (s), distal one much shorter than proximal one, and three basal micro s-chaetae (bms), of which a long dorsal one (Fig. 28), Ant. II with three bms and one latero-distal s, Ant. III with one bms and five distal s (including one lateral), without additional s-chaetae. S-chaetae on Ant. IV weakly differentiated. Organite hook-like, close to subapical micro s-chaeta, which is long and bent (Fig. 29).

Common chaetae often slightly serrated at the posterior part of Abd. V. S-formula as 4,3/2,2,2,3,5(6?) (s), 1,0/0,0,1 (ms) (Fig. 26). Ms on Abd. III as large as s-chaetae. Tergal s-chaetae much shorter than common chaetae and well distinguishable. Medial s-chaetae on Th. II-Abd. III situated in mid-tergal position. On Abd. V, three dorsal s-chaetae (triplet: al, accp1, accp2) short. Two lateral s-chaetae long, migrated to dorsal side and integrated to dorsal triplet (Fig. 31). One additional thin chaeta of unclear nature present on lateral side of Abd. V (notated as “ss?” in Fig. 31 and not shown in Fig. 26). Macrochaetae smooth and long, 1,1/3,3,3 in number, medial ones on Abd. VI more or less the same length as the dens and 3.8 times longer than mucro. Foil chaetae at the tip of abdomen absent. Axial chaetotaxy for abdomen 4–5,4–5,4–5, ca. 8 (difficult to observe in most individuals). All thoracic segments without ventral chaetae.

Unguis of normal shape, without teeth. Empodial appendage 0.5–0.6 as long as unguis. All tibiotarsi with additional chaetae: 2–3 chaetae on Legs I and II, and about five on Leg III. Tibiotarsal tenent hairs not clavate. Ventral tube with 3+3 laterodistal and 5–6 posterior chaetae, anteriorly without chaetae. Tenaculum with 4+4 teeth and two chaetae. Anterior furcal subcoxa with ten, posterior one with five chaetae (from one individual we could observe). Anterior side of manubrium with 1+1 chaetae. Dens of medium length, with crenulation, with 12 anterior and five posterior chaetae (Fig. 30). Mucro tridentate. Ratio manubrium : dens : mucro = 2.7–3.0 : 3.6–3.9 : 1.

The species is named after its remarkable PAO.

Known only from type locality and Swellendam, from indigenous vegetation (fynbos and Afromontane forest).

The new species has a unique PAO with large inner denticles visible at any magnification. All s-chaetae of Abd. V (al, accp1, accp2, accp3, accp4) are in one dorsal group, while in other species of Cryptopygus the triplet ‘al+accp1+accp2’ and duplet ‘accp3+accp4’ are placed in dorsal and lateral positions, respectively. The ms-formula 1,0/0,0,1 (vs. 1,1/1,1,1 or 1,0,1,0,0) is also unique.

Holotype and 21 paratypes: South Africa • Western Cape, Cederberg Wilderness Area, Wolfberg Cracks; 32.471507S, 19.278397E; 19 Feb. 2011; C. Janion-Scheepers leg.; litter, Tullgren extraction; RSA11_CED002. Holotype and three paratypes deposited on two slides at SAMC, six paratypes on three slides deposited at SMNG, four paratypes on two slides deposited at MSPU, and eight paratypes on four slides at NMHN. Ten paratypes in ethanol deposited at SAMC.

South Africa • Western Cape, Cederberg Wilderness Area; 32.310167S, 19.175183E; Oct. 2008, C. Janion-Scheepers leg.; pitfall trap, RSA08_CED001.

Form with two chaetae on the basal part of the posterior side of the dens (see text below) from: South Africa, Northern Cape, Ezeljacht farm, 20 km from Sutherland, 32.4105S, 20.57747E, 1550m asl, 16 Jul. 2007, litter of shrub, C. Janion-Scheepers leg, RSA09_SUT001.

Form with three chaetae on the basal part of the posterior side of the dens (see text below) from: South Africa, Western Cape, Mont Rochelle Nature Reserve, Franschoek, 33.902967S, 19.158950E, 06 Oct. 2008, Litter trap with Galenia litter (MR510), C. Janion-Scheepers leg.

8+8 ocelli. Macrochaetae short. Anterior side of manubrium with 1+1 chaetae. Dens of medium length. Mucro tridentate.

Body size 0.6–0.9 mm. Body grey, Abd. V well separated from Abd. IV and fused with Abd. VI, slightly swollen (Figs 24, 33). Cuticle unmodified. Ocelli 8+8 (Fig. 36). PAO more than three times as long as ocellus, about as long as width of Ant. I and 1.8–2 times as long as inner unguis length. Maxillary head with unmodified lamellae. Maxillary outer lobe with four sublobal hairs, maxillary palp bifurcate. Labral formula as 3/5,5,4, edge of labrum not reduced. Labium with five usual papillae (A–E), guard chaetae e7 present, three proximal and four basomedian chaetae. Ventral side of head with 4+4 chaetae. Ant. I with two ventral s-chaetae (s) and three small basal micro s-chaetae (bms), two dorsal and one ventral (one dorsal large) (Fig. 34), Ant. II with three bms and one latero-distal s, Ant. III with one bms and five distal s (including one lateral), without additional s-chaetae. S-chaetae on Ant. IV weakly differentiated. Organite and subapical micro s-chaeta of normal shape, small and set together as normal.

Common chaetae smooth. S-formula (Fig. 32) as 4,3/2,2,2,3,5 (s), 1,0/0,0,0 (ms). Tergal s-chaetae much shorter than common chaetae and well distinguishable. Medial s-chaetae on Th. II-Abd. III situated in mid-tergal position. On Abd. V all s-chaetae short subequal. Macrochaetae short, 1,1/3,3,3 in number, medial ones on Abd. VI 0.3–0.4 times longer than dens and 0.3–0.7 times longer than mucro. Foil chaetae at the tip of abdomen absent. Axial chaetotaxy as 8,7/4,4,4,7 (based on one individual). All thoracic segments without ventral chaetae.

Unguis of normal shape, without teeth. Empodial appendage about 0.6 as long as unguis. Tibiotarsi without additional chaetae on Leg I and II (21 chaetae), and with several chaetae on Leg III (>26). Tibiotarsal tenent hairs pointed. Ventral tube with 4+4 laterodistal and 5–6 posterior chaetae, anteriorly without chaetae. Tenaculum with 4+4 teeth and two chaetae. Anterior furcal subcoxa with 12–13, posterior one with 5–6 chaetae. Anterior side of manubrium with 1+1 chaeta, posterior side with 4+4 laterobasal and about 22 chaetae on main part, with a pair of lateral chaetae (Fig. 35). Dens normal, with crenulation, with 11–12 anterior and six posterior chaetae (three basal and two at middle and one subapical and very small). Mucro tridentate. Ratio manubrium : dens : mucro = 4.4–5.7 : 4.3–4.7 : 1.

The name is derived from the swollen posterior part of abdomen.

Known from mostly dry, mountainous areas, from the Northern Cape (Sutherland), the Cederberg Wilderness area, and Franschhoek (not as dry as previous two sites).

Considering all species in the Cryptopygus complex, the combination of 8+8 ocelli and tridentate mucro is unique. The only species resembling our species is Proisotoma (Isotomina) pseudominuta Schött, 1927, described from Cameroon. However, this species has clavate tenent hairs and a shorter dens, while Cryptopygus inflatus sp. nov. does not have clavate tenent hairs.

Some variation exists in the material examined and two forms of unclear status can be recognized; both have an ms on Abd. I (1,0/1,0,0) while C. inflatus sp. nov. does not. These two forms differ as follows:

a. Specimens from Sutherland (SUT002) have an ms and two chaetae on the basal part of the posterior side of the dens.

b. Specimens from Mont Rochelle (MR510) have an ms on Abd. I and three chaetae on the basal part of the posterior side of the dens like in C. inflatus sp. nov.

Holotype and six paratypes: South Africa • Northern Cape, Ezeljacht farm, 14 km from Sutherland; 32.4105S, 20.57747E; 1550 m asl; 16 July 2009; C. Janion-Scheepers leg.; shrub litter; RSA09_SUT002. Holotype and five paratypes on four slides deposited at SAMC, one paratype on one slide deposited at MSPU.

Several specimens from South Africa • Western Cape, Jonkershoek Nature Reserve; 33.989350S, 18.957433E; 30 July 2009 and 12 Aug. 2010; C. Janion-Scheepers leg.; litter trap (32).

Anterior side of manubrium with 1+1 chaetae. Dens of medium length. Mucro tridentate. All s-chaetae of Abd. V elongated.

Body size 0.9–1.3 mm (Fig. 25). Body pale, with scattered black granules of pigmentation, more concentrated on head, eye spots and posterior of trunk. Body tubular. Abd. V well separated from Abd. IV and fused with Abd. VI (Fig. 45). Cuticle with thin hexagonal primary granulation (“smooth”). Ocelli range from three to seven on each side (Figs 37–41) (see Discussion). PAO rather narrow, sharply constricted, with small inner denticles, longer than width of Ant. I (1.1–1.3) and inner unguis length (1.3–1.4). Maxillary head without modified lamellae. Maxillary outer lobe with four sublobal hairs, maxillary palp bifurcate. Labral formula as 4/5,5,4, edge of labrum not reduced. Labium with five usual papillae (A–E), guard chaetae e7 present, three proximal and four basomedian chaetae. Ventral side of head with 4–5+4–5 chaetae. Ant. I with three ventral s-chaetae (s) and two small basal micro s-chaetae (bms), dorsal and ventral, the former set together with long chaeta-like micro s-chaeta, Ant. II with three bms and one latero-distal s, Ant. III with one bms and six distal s (including two lateral), without additional s-chaetae. S-chaetae on Ant. IV weakly differentiated. Organite pin-like.

Common chaetae rather long, smooth. S-formula as 4,3/2,2,2,3,5 (s), 1,0/1,0,0 (ms) (Fig. 42). Tergal s-chaetae short (apart from Abd. V) and well different from common chaetae. Medial s-chaetae on Th. II-Abd. III situated in mid-tergal position, on Abd. I–III between Mac1 and Mac2. Abd. V with five s-chaetae arranged with three dorsal ones (al, accp1, accp2), long and slender, and two lateral ones (accp3, accp4), long and slightly thickened so hardly distinguishable from common chaetae (Fig. 45). Macrochaetae smooth and long, 1,1/3,3,3 in number (Th. II-Abd. III), medial ones on Abd. VI 0.7–0.9 as long as dens and 2.8–3.7 times longer than mucro. Foil chaetae at the tip of abdomen absent. Axial chaetotaxy abundant 10–11,8–9/4–6,4–6,4–6. Thorax (incl. Th. III) without ventral chaetae.

Unguis of normal shape, without lateral and inner teeth. Empodial appendage about half as long as unguis. Tibiotarsi with additional chaetae, at whole with 23–24 ones on Leg I and II, and more than 25 on Leg III (Fig. 46). Tibiotarsal tenent hairs pointed. Adult males with stick-like thin spurs on Tibiotarsi III. Ventral tube with 3+3 laterodistal and six posterior chaetae, anteriorly without chaetae. Tenaculum with 4+4 teeth and a chaeta. Anterior furcal subcoxa with 13–15, posterior one with 4–6 chaetae. Anterior side of manubrium with 1+1 chaetae. Posterior side of manubrium with 12–14+12–14, including 5+5 on basolateral flaps. Dens with 10–12 anterior chaetae (Figs 43, 44). Posterior side of dens crenulated and with five chaetae (three basal and two at the middle). Mucro tridentate. Ratio manubrium : dens : mucro = 2.8–3.4 : 3.8–5.1 : 1.

The name is derived from the very long s-chaetae on Abd. V.

Cryptopygus longisensillus sp. nov. is currently known from Sutherland (Northern Cape) and Jonkershoek, Stellenbosch (Western Cape).

The species belongs to a group of forms having ocelli, tridentate mucro and rather long dens (C. insignis Massoud & Rapoport, 1968, C. patagonicus Izarra, 1972, C. quadrioculatus (Wise, 1970), C. tricuspis Enderlein, 1909) (Table 1). Two species, C. insignis and C. tricuspis have 1+1 chaetae (vs. 0+0 in C. longisensillus sp. nov.) on ventral side of Th. III and common s-chaetae (vs. elongated in new species) on Abd. V. Due to insufficient descriptions the morphology of C. patagonicus and C. quadrioculatus is less understood. Both species differ from C. longisensillus sp. nov. in fewer chaetae (eight and nine vs. 10–12) on anterior and more chaetae (six vs. five) on posterior sides of dens. C. quadrioculatus shows specific position of ocelli with one anterior and one posterior at a distance.

Cryptopygus longisensillus sp. nov. shows a unique pattern of s-chaetae on Abd. V not found before in the genus: all five s-chaetae elongated while s-chaetae of dorsal triplet thin, two lateral ones slightly thickened, representing a s-pattern of type “4” according to the classification of Potapov et al. (2017). The variability in the number of ocelli is unusual: among six individuals of one population we recorded variants with three, four, five, and seven ocelli. Two ocelli near the PAO are always well visible, while the other ones are only recognizable by weak swellings of the cuticle. The nature of this variability is not fully clear and calls for further study. The only similar case is known in C. insignis (fig. 4A in Massoud and Rapoport 1968). In the specimens from South Africa, Western Cape, Jonkershoek Nature Reserve, six posterior chaetae on dens were found. This variation also calls for further study.

South Africa • Western Cape, Kogelberg Nature Reserve; 34.331833S, 18.952467E; 04 Oct. 2011, C. Janion-Scheepers leg.; litter (Mimetes sp.), Tullgren extraction; RSAII_KOG010 • Western Cape, Orangekloof, Table Mountain National Park; 33.983883S, 18.403050E; 24 Oct. 2011, C. Janion-Scheepers leg.; indigenous vegetation litter, Tullgren extraction; RSAII_OK026 • Western Cape, Orangekloof, Table Mountain National Park; 33.975917S, 18.407667E; 24 Oct.2011; C. Janion-Scheepers leg.; indigenous vegetation litter, Tullgren extraction; RSAII_OK029 • South Africa, Western Cape, Table Mountain National Park, Cape Point, Platboom; 34.336017S, 18.447633E; 06 Aug. 2009; Tullgren extraction; RSA09_PEN008) • South Africa, Western Cape, Outeniqua, 33.887583S, 22.424067E, Afromontane Forest leaf litter Tullgren extraction (OUTF38), 14.ii.2013, A. Liu leg.; SAF-627 • Prince Albert: Swartberg South: Swartberg south slope; 12 March 2019; L. Deharveng & A. Bedos leg.; moss, moss on rock, Berlese; SAF-614, • Prince Albert, Swartberg North: Swartberg crest, 12 March 2019; L. Deharveng, C. Janion-Scheepers & A. Bedos leg.; moss, moss on rock, Berlese; SAF-401 • Constantia: Orange Kloof; 09 Jan. 2012; L. Deharveng & A. Bedos leg.; restio, litter, litter and humus, Berlese.

4+4 to 6+6 ocelli. Manubrium with 1+1 chaetae on anterior side. Dens stout, not crenulated, with 4–6 anterior and 3–4 posterior chaetae. Mucro bidentate. Clavate tibiotarsal hairs present.

Currently known from the indigenous vegetation from the larger Table Mountain National park area, and the Outeniqua (George) area.

So far several subspecies and species resemble typical antarctic species C. antarcticus Willem, 1902 (C. antarcticus maximus Deharveng, 1981, C. antarcticus travei Deharveng, 1981, C. antarcticus reagens (Enderlein, 1909), C. quinqueoculatus Izarra, 1970, C. hirsutus Denis, 1931, C. badasa Greenslade, 1995, C. araucanus Massoud & Rapoport, 1968) and combine a group which is named “antarcticus complex” by us. In fact, they all almost fit to the strict diagnosis of the genus Cryptopygus proposed by Rusek (2002). This complex, often recorded just under the name ‘C. antarcticus’, is widely distributed in the sub-Antarctic (Deharveng 1981, Stevens et al. 2006) and less in temperate zones of the Southern Hemisphere (South America: Mari Mutt and Bellinger 1990; Australia: Greenslade, 1994; New Zealand: Babenko and Minor 2015), with C. hirsutus extending into Costa Rica. In South Africa, we have also found the forms with clavate tenent hairs on the tibiotarsi and the characteristic ‘antarcticus-like’ furca and so then belonging to ‘C. antarcticus’ complex. They differ from typical C. antarcticus at least by having fewer ocelli (three anterior and one or two posterior) and lighter pigmentation. So far, the following forms were found:

Reliable taxonomical decision on their status cannot be made at present and preliminary study of all known and unknown forms is underway.

Isotominella geophila Delamare Deboutteville, 1948

The genus belongs to the Cryptopygus complex. Ocelli absent. Medial s-chaetae in posterior position from Th. II to Abd. IV. Number of s-chaetae 3,3/2,2,2,2,3. Foil chaetae at the end of abdomen absent.

The genus Isotominella was described from Ivory Coast and was subsequently given a detailed diagnosis by Jordana et al. (2009) based on material of I. geophila from Algeria. The taxon was considered a member of the Cryptopygus complex and was said to differ from related genera mainly by the crenulation, which is developed only in the proximal half of the dens. According to Jordana et al. (2009), in other genera of the complex this crenulation is either absent (i.e., dens is “smooth”), or extends further along the posterior side of dens, as in Hemisotoma Bagnall, 1949.

In our view, the crenulation is a flexible character within the genera of the Cryptopygus complex and depends on the length of furca, which can vary highly within a large genus, e.g., in Cryptopygus s. str., and particularly, among its representatives in South Africa (Figs 14, 30, 35, 43). Two species of the genus Isotominella, I. geophila and I. laterochaeta sp. nov. share a remarkable s-chaetotaxy, particularly, the posterior position of medial s-chaetae on body tergites, a reduced s-formula (3,3/2,2,2,2,3), and differentiation of s-chaetae on Abd. V with two long dorsal and one short lateral s-chaetae. The mouth parts of the two species are uncommon: the terminal ‘sensilla’ of papilla A and B are rod-like, the number of basolateral chaetae of labium are increased, the labrum has two prelabral chaetae, the number of sublobal hairs of maxillary outer lobe is reduced (three in the new species and two in I. geophila), and the maxillary head is modified. The presence of 7–9 basolateral chaetae on the labium (vs. commonly five as determined by Fjellberg 1999) in I. laterochaeta sp. nov. have not been recorded so far for Isotomidae. This remarkable feature is less pronounced in I. geophila in which this number is variable (five or six). Six basolateral chaetae on the labium were found in the genus Pauropygus (Potapov et al. 2013) in P. projectusPotapov et al., 2013, P. caussaneli, P. pacificusPotapov et al., 2013, which also shows the posterior position of the s-chaetae on tergites. The two genera share other important characters and are probably closely related (Potapov et al. 2013). Labral chaetae are normally pressed to the labrum in Isotomidae, while they are projected forward in the new species (the character is unclear for I. geophila). Isotominella also resembles the blind genera CylindropygusDeharveng et al., 2005 (Europe) and Dagamaea Yosii, 1965 (East Asia and North America) but reliably differs by the posterior (vs. mid-tergal) position of the s-chaetae on the body tergites. A table to compare all the genera of the complex Cryptopygus is given by Jordana et al. (2009).

Holotype and eight paratypes: South Africa • Western Cape, Platboom, Cape Point National Park; 34.336017S, 18.447633E; 14 Nov. 2010; L. Deharveng and A. Bedos leg.; soil; SAF 318. Holotype and two paratypes on three slides deposited at SAMC, three paratypes on three slides at NMHN, and three paratypes on three slides at MSPU.

Blind. Labium with 7–9 basolateral chaetae. Chaetae on ventral side of Th. III present. Labial palp with 16 guard chaetae. Three sublobal hairs on maxillary outer lobe. Anterior side of manubrium with 9–10+9–10 chaetae. Dens with 12–14 anterior and four posterior chaetae. Mucro bidentate.

Body size 0.8–1.0 mm. White, without pigmentation, appearance as Mucrosomia caeca (Fig. 47). Mouth cone projected forward. Abd. V well separated from Abd. IV and fused with Abd. VI (Fig. 53). Cuticle “smooth”. Without ocelli. PAO small, not constricted, less than a half of width of Ant. I and 0.5–0.7 as long as inner unguis length. Maxillary head with slender lamellae and thin capitulum. Maxillary outer lobe with three sublobal hairs, maxillary palp simple (Fig. 52). Labral formula as 2/5,5,4, edge of labrum not reduced. Chaetae of labrum conspicuously projected forward (Fig. 50). Labral chaetae of middle and distal rows thicker than chaetae of proximal row. Inner chaetae of distal row shifted to more proximal position and integrated to middle row resulting the impression of 5,7,2 formula. Up to ten clypeal chaetae. Labium with five papillae (A–E), 16 guard chaetae (guard chaetae e7 present), and three proximal chaetae (Fig. 49). Terminal ‘sensilla’ of papillae A and B rod-like. All inner guard chaetae (b3, b4, d3, d4, e2, e3, e5, e6) strongly curved. With two curved and small accessorial hypostomal chaetae (h1, h2), main hypostomal chaeta (H) absent (Fig. 49). Basal part of labium with four basomedian and 7–9 basolateral chaetae (Figs 48, 52). Ventral side of head with numerous chaetae (up to 13 on one side along ventral line), with numerous chaetae at base of labium (Fig. 48). Normal s-chaetae and basal micro s-chaetae hardly differentiated on antennae, their number difficult to ascertain. Ant. I with many chaetae and at least two ventral s-chaetae (s) mixed with normal chaetae (or thinner s-chaetae). Ant. III with five distal s (including one lateral), without additional s-chaetae. S-chaetae on Ant. IV weakly differentiated. Organite small, rudimental, close to subapical micro s-chaeta, which is long and bent (Fig. 51).

Common chaetae long. S-formula as 3,3/2,2,2,2,3 (s), 1,0/1,0,0 (ms) (Fig. 54). Tergal s-chaetae longer than common chaetae, less distinguishable on Th. II and III. Medial s-chaetae on Th. II-Abd. III situated in p-row of chaetae. On Abd. V, two dorsal s-chaetae (accp1, accp2) long, one lateral s-chaeta short (Fig. 53). Macrochaetae smooth and long, 1,1/3,3,3,4 in number. Macrochaetae on Abd. V longer than on Abd. VI: 0.8–0.9 and 0.6–0.7 as long as the dens and 3.3–3.5 and 2.3–2.8 times longer than mucro on Abd. V and VI, respectively. One thin macrochaetae (possibly additional s-chaeta) present in latero-ventral position on Abd. V. Foil chaetae at the tip of abdomen absent. Axial chaetotaxy for Th. II-Abd. IV 14–16,7–8/5–6, 5–6, 5–6, ca. 6. Th. III with 2–4+2–4 ventral chaetae.

Unguis of normal shape, without inner tooth and with two lateral teeth. Lateral teeth often asymmetrical in size and position. Empodial appendage thin, without lamellae, 0.6–0.7 as long as unguis. All tibiotarsi with many additional chaetae: Tibiotarsal tenent hairs not clavate. Ventral tube with 5–8+5–8 laterodistal and 6–9 posterior chaetae (with two larger in distal position), anteriorly without chaetae. Tenaculum with 4+4 teeth and two chaetae (rarely more). Anterior furcal subcoxa with 19–23, posterior one with 11–15 chaetae. Anterior side of manubrium with 9–10+9–10 chaetae arranged in two symmetrical group (Fig. 58), with distal pair thickened. Posterior side of manubrium with 11–14+11–14 chaetae on main part, 4+4 laterodistal and 2(3)+2(3) lateral chaetae (Fig. 59). Dens of medium length, with weak crenulation at the middle, with 12–14 anterior and four posterior chaetae (Figs 55–57). One minute chaeta-like process often seen close to distal chaeta. Mucro bidentate. Ratio manubrium : dens : mucro = 3.0–3.9 : 3.2–4.3 : 1.

The name is derived from its many lateral chaetae on the basal part of labium.

Known only from type locality (Cape Point National Park).

Isotominella laterochaeta sp. nov. and I. geophila (type species of the genus) differ by the number of anterior chaetae on the manubrium (9–10+9–10 vs. 1–4+1–4), chaetae on ventral side of Th. III (present vs. absent), number of guard chaetae on labial palp (16 vs. 13–14), and number of sublobal hairs (three vs. two) on maxillary outer lobe. Minute chaeta placed at the middle of posterior side of dens, numerous postlabial chaetae, and absence of hypostomal chaeta H are unique to I. laterochaeta sp. nov. The two last characters are unknown for I. geophila.