Philotella glabrasterna, Gao & Palacios-Vargas & Arango & Bu, 2024

Gao, Yan, Palacios-Vargas, José G., Arango, Angela & Bu, Yun, 2024, First records of Micranurida and Philotella (Collembola, Neanuridae, Pseudachorutinae) from China with the description of three new species, Zootaxa 5555 (1), pp. 116-124 : 120

Philotella glabrasterna sp. nov., Arango, Gao & Bu

Figures 10–19

Material examined. Holotype: female (slide No. HB-C2016032) ( SNHM), North China, Hebei Province, Pingquan, Liaoheyuan , 41°19.21’ N 118°26.42’ E, 1230 m alt., soil samples from mixed forest, 13-VII-2016, collected by Yun Bu. Paratypes: 5 females, 6 males, slide Nos. HB-C2016032, HB-C2016049, HB-C2016050, same data as holotype. All specimens are deposited in Shanghai Natural History Museum ( SNHM) .

Diagnosis. Tiny, unpigmented species characterized by the presence of PAO with 7–10 vesicles and the absence of ocelli; six hammer-like sensilla on Ant. IV; seta p2 only present on terga Th. II and III; thickened, hammer-like sensilla present laterally on Th. II and on Abd. IV.

Description. Body short and broad, length 0.48–0.80 mm, holotype 0.62 mm ( Fig. 10 ). White in ethanol. Tegument granulation uniform.

Antennae slightly shorter than head, Ant. III–IV fused dorsally ( Figs 11–12 ). Ant. IV with trilobed apical vesicle ( Fig. 11 ); external ms, subapical or, seta i, six banana-like sensilla present and one tiny sensillum-like (ms) seta close to S8 ( Fig. 12 ). Antennal organ of Ant. III typical, inner sensilla small, both sgv and sgd long, sgd curved, sgv S-like, ventral ms present ( Fig. 12 ). Ant. I–II with 6–7 and 11–12 setae, respectively.

Head without ocelli, PAO rounded or slightly elliptic, consisting of 7–10 round vesicles ( Fig. 1 ). Maxilla with two lamellae and inner one hook-shaped ( Fig. 14 ). Mandible with three apical teeth ( Fig. 15 ). Labrum with 4/3, 5, 2 setae ( Fig. 13 ). Labium with 11 pairs of setae and without sensory papillae ( Fig. 16 ). Head ventrally with 2+2 postlabial setae ( Fig. 16 ).

Dorsal chaetotaxy symmetrical and reduced ( Fig.10 ). Ordinary setae acuminate, lateral sensilla on Th. II and dorsal ones on Abd. IV clearly thickened, and blunt ended ( Fig. 10 ); other dorsal sensilla slender, thin and longer than ordinary setae, total number of tergal sensilla as usual: 22/11111; lateral ms present only on Th. II ( Fig. 10 ). Head with unpaired seta d0 and 3 setae on ocular field ( Fig. 10 ). Th. I with 3+3 setae ( Fig. 10 ). Setae p2 present on Th. II and Th. III, absent on Abd. I–V. Abd. V only with 1+1 axial setae ( Fig. 10 ).

Thoracic sterna without setae. Ventral tube with 4+4 setae. Furcal remnant absent, 5–6 normal setae present on each side of Abd. IV. ( Fig. 17 ). Abd. IV with 7–8 normal setae on each side ( Fig. 17 ). Female with 2 pairs of pregenital setae, 8–12 circumgenital setae and 2 eugenital ( Fig. 17 ); male with 2 pairs of pregenital setae, about 9–11 circumgenital and 4 + 4 eugenital setae ( Fig. 19 ). Anal valves each with 10 normal setae and 1 tiny microsetae ( Figs 17, 19 ).

Legs I–III with 1, 2, 2 setae on subcoxae, 3, 6, 6 setae on coxae, 3, 6, 6 on trochanters, and 12, 12, 10–12 setae on femora. Tibiotarsi with 19–19–18 setae ( Fig. 18 ). Unguis toothless, unguiculus absent.

Etymology. The species name glabrasterna refers to the lack of setae in the middle part of sterna II and III.

Remarks. Philotella glabrasterna sp. nov. is similar to P. oligotricha Babenko, Shveenkova & Potapov, 2022 in the strong reduction of setae on Abd. V, where only one row with p1, p3=(ss) and p5 exist. They differ in the absence of eyes in the new species (vs 3 + 3 eyes in P. oligotricha). Both have similar head chaetotaxy, but the last species lacks setae c1 and p3. Dorsal chaetotaxy of other parts of the body also significantly differs in these two species: in P. glabrasterna Di groups bear three setae on Th. II–III and two setae in the same positions only on Abd. I–IV, while P. ologotricha has 2 setae on all terga. Besides the lateral ss on Th. II and the dorsal ones on Abd. IV in P. glabrasterna sp. nov. are subcylindrical, while in P. oligotricha they are setae-like.

Figures

FIGURES 10–19. Philotella glabrasterna sp. nov. 10, body dorso-lateral chaetotaxy; 11. Antenna, dorsal view; 12, Ant. III and IV, ventral view; 13, labrum chaetotaxy; 14, Maxilla; 15, Mandible; 16, labium chaetotaxy and postlabial setae; 17, Abd. I–VI of female, ventral view; 18, tibiotarsus 1; 19, Abd. V–VI, ventral view, showing male genital plate.

FIGURES 1–9. Micranurida hunanensis sp. nov. 1, dorsal body chaetotaxy; 2, Ant. III and IV, ventral view; 3. Ant. III and IV, dorsal view; 4, Maxilla, two positions; 5, Mandible; 6, labrum chaetotaxy; 7, labium chaetotaxy and postlabial setae; 8, Abd. I–VI of a female, ventral view; 9, tibiotarsus 1.