Isotopenola delicata, Potapov, Mikhail, Babenko, Anatoly, Fjellberg, Arne & Greenslade, Penelope, 2009

Potapov, Mikhail, Babenko, Anatoly, Fjellberg, Arne & Greenslade, Penelope, 2009, Taxonomy of the Proisotoma complex. II. A revision of the genus Subisotoma and a description of Isotopenola gen. nov. (Collembola: Isotomidae), Zootaxa 2314, pp. 1-40 : 34-36

Isotopenola delicata sp. nov.

Figs 10 , 106–115 , Tab. 2

Material. Holotype, female, Australia, New South Wales, Urila, 30 km S Queanbeyan, Tilembaya [35°34’S, 149°17’E], pitfalls, 15–25.iv.1990, leg. R. Farrow ( SAMA). Paratype, female, the same data as the holotype.

Description. Size 1.1–1.3 mm. Colour dark (the individuals partly cleared). Body stout, with moderate cryptopygy ( Fig. 107 ). Cuticular granulation fine and uniform, part of body and head with secondary granulation. With 8+8 ocelli, G and H smaller and hardly visible ( Fig. 115 ). PAO wide, elliptical, without constriction, about 1.5–2.0 as long as ocellus diameter and shorter than inner unguis (0.9:1). Maxillary palp simple, 4 sublobal chaetae present. Labrum with 2/554 chaetae. Labium with all papillae A–E present, papilla E with 5 guard chaetae (e5 and e7 probably absent), proximal chaetae 3. Basomedial field of labium with 4 chaetae. Ventral side of head with 4+4 postlabial chaetae ( Fig. 108 ). Ant.1 with 12–13 common chaetae, 2 bms (dorsal and ventral) and 2 ventral sensilla (s) ( Fig. 115 ), Ant.2 with 3 bms and 1 distal s, Ant.3 without bms and with 5 distal s, including one lateral in АО. Inner sensilla of АО clearly broadened, additional sensilla absent. Ant.4 with numerous poorly differentiated sensilla, subapical organite small, microsensillum present. All terga with dense cover of uniform chaetae. Macrochaetae short, differentiated only laterally on Th.II–III and on abdominal tip. Dorsal axial chaetom of Th.II–Abd.III as 9–11,8–9/7–8,6–7,6–7. Tergal sensilla distinctly differ from ordinary chaetae, short and slender. The actual number of primary sensilla masked by variable numbers of many additional sensilla uniformly distributed on the terga. Total number of sensilla about 12–14,10–11/6–7,9–11,9–10,15–17,23 ( Figs 10 , 112–113 ). The number of tergal microsensilla 10/101. Sterna of Th.III without chaetae.

Unguis with clear inner tooth. Ti.1–3 with additional proximal chaetae, usually the total numbers 22, 24– 25, 27–29 ( Figs 109–111 ). Tibiotarsal tenent chaetae 1–2–2, clearly clavate, longer than inner edge of unguis (U3: t.ch. = 0.67: 1). Ventral tube with 4+4(5) lateral and 4 posterior chaetae (seen in only one specimen). Tenaculum with 4+4 teeth and one chaeta. Submedial setaceous fields on Abd.III sterna with 4–5 chaetae, anterior furcal subcoxae with 7–10 chaetae, posterior subcoxae with 6–8 ( Fig. 106 ). Manubrium without anterior chaetae, posterior face with about 18 chaetae and several on laterobasal lobes. Dens with one anterior and 6 posterior strong chaetae. Mucro long and rather wide, with 2 teeth, more or less clearly set off from dens ( Fig. 114 ). Ratio of manubrium: dens: mucro = 5.6: 3.6: 1. Setulae on the anal lobes differentiated in size, medial one longer on the unpaired upper lobe, whereas one setula of the lateral lobe clearly smaller than others.

Affinity. The presence of numerous sensilla on body, not needle-like but normal chaetae, and 4+4 postlabial chaetae are shared with I. loftyensis . The latter differ by 19 chaetae on Ant.1 (only 12–13 in I. delicata ), full set of microsensilla (10/ 101 in I. delicata ), less complete number of e-guard chaetae. Isotopenola delicata sp. nov. differs from all species of Cryptopygus described by Salmon from New Zealand in having more chaetae on dens.

Distribution. Currently known only from the type locality. It was originally recorded ( Farrow & Greenslade 1992) as Cryptopygus sp. A large population was observed climbing Eucalyptus tree trunks after heavy rain.

Name derivation. Named after many sensilla on body. Latin ‘ delicatus’ means delicate, sensitive.

Figures

FIGURES 9 – 12. Sensillar chaetotaxy of Isotopenola: 9, Isotopenola australis (5,5 / 4,4,4,4,5); 10, Isotopenola delicata sp. nov. (sensillar polychaetosis); 11, Isotopenola loftyensis (sensillar polychaetosis); 12, Isotopenola nilgiris (4,4 / 3,3,3,3,4).

FIGURES 106 – 115. Isotopenola delicata sp. nov.: 106, ventral chaetotaxy of Abd. II – IV; 107, profile of three last abdominal segments; 108, postlabial chaetae (encircled); 109 – 111, chaetotaxy of tibiotarsi of legs 3 (109), 2 (110), and 1 (111); 112, Th. II; 113, Abd. V; 114, mucro and dens; 115, ocelli, PAO, and Ant. 1, sf – II and sf – III – setaceous fields on Abd. II and III, respectively.