Cryptopygus longisensillus, Potapov & Janion-Scheepers & Deharveng, 2020

Potapov, Mikhail B., Janion-Scheepers, Charlene & Deharveng, Louis, 2020, Taxonomy of the Cryptopygus complex. III. The revision of South African species of Cryptopygus and Isotominella (Collembola, Isotomidae), ZooKeys 945, pp. 99-127 : 99

Cryptopygus longisensillus sp. nov. Figures 25 , 37-41 , 42-46

Type material.

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.

Other material.

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).

Diagnosis.

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

Description.

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.

Etymology.

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

Distribution and ecology.

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

Discussion.

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.

Figures

Figures 23 - 25. Appearance and macrochaetotaxy of C. postantennalis sp. nov. (23), C. inflatus sp. nov. (24), and C. longisensillus sp. nov. (25).

Figures 37 - 41. Variation of number of ocelli in C. longisensillus sp. nov. 37 5 + 5 ocelli 38 3 + 3 ocelli 39 4 + 4 ocelli 40, 41 7 + 7 ocelli.

Figures 42 - 46. C. longisensillus sp. nov. 42 macrochaetotaxy and s-ms-pattern 43, 44 dens, lateral (43) and anterior (44) views 45 Abd. IV and fused Abd. V and VI 46 tibiotarsus and claw of Leg III. Abbreviations: ss s-chaeta, msms-chaeta.