Anurida octoculata Babenko, 2023

Babenko, A. B., 2023, A NEW SPECIES OF THE HAMMERAE-GROUP OF THE GENUS ANURIDA LABOULBÈNE, 1865 (COLLEMBOLA: NEANURIDAE) FROM PRIMORSKY KRAI, Far Eastern Entomologist 484, pp. 9-16 : 10-14

Anurida octoculata Babenko , sp. n.

https://zoobank.org/NomenclaturalActs/ 83F82906-531A-49F1-8710-D75D543FBB19

Figs 1–14

MATERIAL. Holotype: ♀, Russia: Primorsky Krai, Vladivostok Botanical Garden , 43.2222°N 131.9936°E, coniferous-broad-leaved forest, winter traps, 20 November 2016 – 11 March 2017, leg A.D. Komisarenko. Paratypes: 12♀ and 2♂, same data as holotype. The types are kept in the collection of Zoology and Ecology Department of the Moscow State Pedagogical University, Russia ( MSPU) .

DIAGNOSIS. A large species of the hammerae -group characterized by the presence of 4+4 uncoloured ocelli, six blunt sensilla on Ant.4, two of which (S 1 and S 2) being much thinner than others, an oval PAO with about 30 finely granulated lobes, mandibles with five teeth, maxillae with all lamella serrated, one of which (L 2) passing much beyond the capitulum tip, and by the absence of p 1 setae on all terga from Th.2 to Abd.4, and a 3 setae on Abd.4–5.

DESCRIPTION. Length of holotype without antennae: 2.4 mm. Colour of live specimens unknown, all available specimens kept in alcohol without any traces of a dark pigment even on ocular area. Body shape typical of the hammerae -group: Abd.6 wide and with a more or less straight posterior edge ( Fig. 2 ). Integument granulation fine and uniform, cuticle without distinct inner reticulation.

Ocelli present, 4+4 as a rule. PAO elongate, consisting of 28–31 finely granulated lobes, its long axis 3.4–5.7 times as long as diameter of nearest ocellus ( Fig. 12 ). Antennae about as long as head diagonal, shape typical of the genus. Ant.4 with a large 3-lobed apical bulb and 6 curved sensilla, S 1 and S 2 clearly thinner, subapical ms, organite and seta i present ( Fig. 13 ). Ant.3 usually with 19 (18–20) ordinary setae and AO of typical shape, sgd about as long as sgv, inner sensilla rather long, a small ms present ventrally. Ant.1–2 with 7 and 14(15) setae, longest setae on Ant.1 clearly shorter then segment width (0.6–0.7: 1). Labrum with a usual set of setae, arranged as 4/2-3-3-4 ( Fig. 11 ). Apical part of labium with three setae and two small sensillar papillae; basal parts (mentum and submentum) with usual 4+4 setae ( Fig. 10 ), 2+2 postlabial setae present on head along ventral line. Mandibles ( Fig. 9 ) with three small apical teeth set slightly out of line and two larger basal ones. Maxillary capitulum with three apical teeth in main part followed by a smooth cutting edge and three serrate lamellae, L.2 long, reaching much beyond the tip of capitulum ( Figs 7–8 ).

Common dorsal setae clearly differentiated into macro- and microsetae, macrosetae long, erect, rather coarse, but usually smooth, sensilla thin, whip-like, more or less subequal on all terga, their number as usual 22/11111; lateral microsensilla (ms) present on Th.2. Dorsal chaetotaxy as in Figs 1–2 . Main characteristics: tergum of Th.1 with 3+3 setae; setae p 1 absent on all terga from Th.2 to Abd.4; Th.2–3 with sensilla (p 3) in anterior position in front of macrosetae p 4, three setae (a 1, a 3 and a 5) of a -row and seta m 4 present ( Fig. 1 ); Abd.1–3 with 3 a -setae (a 1, a 3 and a 5) and 2+2 macrosetae (p 2 and p 3) between sensilla p 4; Abd.4 with only two a -setae (a 1 and a 4) and a lateral macroseta m 5 between a - and p -rows; Abd.5 always without a 3 ( Fig. 2 ). Thoracic sterna without setae. Ventral tube with four setae on each side. Chaetotaxy of abdominal sterna as in Fig. 5 , sternum of Abd.2 without setae in medial position. Furca reduced to two poorly visible swellings near anterior border of Abd.4 sternum, each with (2)3 tiny setulae without visible alveoli. Each anal valve usually with three small hr -setae.

Chaetotaxy of legs 1–3 as follows: upper subcoxae – 1, 2, 2; lower subcoxae – 0, 2, 2; coxae – 3, 8, 8; trochanters – 6, 6, 6; femora – 13, 12, 11; tibiotarsi – 19, 19, 18 setae, respectively, significant variations infrequent. Tibiotarsal setae rather long and thickened, longest inner setae of B -whorl slightly longer than inner unguis edge (1.1–1.4: 1). Unguis with a clear inner tooth ( Fig. 14 ), lateral ones invisible.

REMARKS. At present, the hammerae -group includes at least ten described species found on both sides of the northern Pacific ( Babenko & Nakamori, 2021). Among them, there are only four congeners lacking axial setae p 1 on all terga from Th.2 to Abd.4 as observed in A. octoculata sp. n.: A. luciae Fjellberg, 1985 , while in this species p 1 can occasionally be present on Th.2–3 ( Fjellberg, 1985b), A. elegans , both recorded from the eastern Palaearctic, A. reducta Fjellberg, 1985 , found so far only in the environs of Fairbanks, Alaska, and the amphi-Beringian A. narli Fjellberg, 1985 . The former two are characterized by a feature rather unusual for the genus, namely, the presence of 7+7(8) ocelli, and both are fairly easy to distinguish from A. octoculata sp. n. Anurida reducta is blind and much smaller than A. octoculata sp. n. (1.0 vs almost 2.5 mm), and although its dorsal chaetotaxy is practically identical to that in A. octoculata sp. n., the level of its differentiation into macro- and microsetae is hardly comparable with that in A. octoculata sp. n. Anurida narli is perhaps the most similar to the new species, since the whole range of variation in the number of ocelli (2–4) also includes that typical of A. octoculata sp. n. Nevertheless, these two species differ quite reliably in the details of dorsal chaetotaxy. In particular, A. narli always has a3 present [on Abd.4–5, as well as] additional short seta p4’ obliquely behind the macrochaeta p4 ( Fjellberg, 1985a: 106). Apart from this, these two species clearly differ in the differentiation of the dorsal chaetom (cf. Figs 1–2 and 3–4 ): in A. narli setae are usually short and thin on anterior part of body, notably coarser towards tip of abdomen [becoming] more distinctly ciliate/serrate there ( Fjellberg, 1985a: 105). A differentiation of dorsal setae in A. octoculata sp. n. is almost the same throughout the body (see Figs 1 and 2 ), while macrosetae are much longer and usually smooth.

The most reliable feature for distinguishing species within the genus Anurida is undoubtedly the fine structure of the mandibles and maxillae. Unfortunately, maxilla and mandible were not examined in detail during the original description of A. narli ; it was only said that they are apparently not different from those of A. reducta ( Fjellberg, 1985a: 105) . This latter statement appears to be fully correct (see Figs 15–18 ), at least as regards the available material from the eastern Chukotka (not types). The study of this material undoubtedly indicates differences in the fine structure of the maxillae in A. octoculata sp. n. and A. narli (cf. Figs 7–8 and 17–18 ), while the mandibles are quite similar (cf. Figs 9 and 15–16 ). Specimens of A. narli from Chukotka and A. octoculata sp. n. also differ in the absence (in A. octoculata sp. n.) or the presence (in A. narli ) of setae in the medial region of Abd.2 sternum (see figs. 5 and 6). This can also be a good diagnostic feature, but it needs to be tested on more specimens from different locations.

DISTRIBUTION. The species is only known from the type locality.

ETYMOLOGY. The name of the new species reflects the number of ocelli, a highly variable character (0–8) within the hammerae- group.

Figures

Figs 1–4. Anurida octoculata sp. n. (1–2) and A. narli (specimen from Chukotka) (3–4). 1 – dorsal chaetotaxy of head and Th.1–2; 2 – dorsal chaetotaxy of Abd.3–6; 3 – dorsal chaetotaxy of head and Th.1–2; 4 – dorsal chaetotaxy of Abd.3–6. Scales: 0.1 mm.

Figs 5–6. Abdominal chaetotaxy of Anurida octoculata sp. n. (5) and A. narli (specimen from Chukotka) (6). Scales: 0.1 mm.

Figs 7–18. Anurida octoculata sp. n. (7–14) and A. narli (specimen from Chukotka) (15– 18): 7–8 – maxillary head (two different view); 9 – mandible; 10 – labium; 11 – labrum; 12 – PAO and ocular field; 13 – Ant.3–4; 14 – tibiotarsus and unguis of hind leg; 15–16 – mandible (two different view); 17–18 – maxillary head (two different view). Scales: Figs 10– 11, 13–14 – 0.1 mm, 7–9, 12, 15–18 – 0.01 mm.