Setanodosa jacquesi, Janion-Scheepers & Deharveng, 2022

Janion-Scheepers, Charlene & Deharveng, Louis, 2022, A shocking-red new species of Setanodosa Salmon, 1942 (Collembola: Brachystomellidae) from South Africa, Zootaxa 5154 (4), pp. 483-495 : 484-488

Setanodosa jacquesi sp. nov.

Figs 1–8

Type material. South Africa, Western Cape Province. Stellenbosch Mountain , floating on water in a rock pool, collected by hand (RSA10_STB002) , 33.9697°S; 18.9006°E, 1000 m above sea level, 29 August 2010, C. JanionScheepers and J. Scheepers leg.

Holotype: one female.

Paratypes: three females and two juveniles.

Material deposit. Three specimens on two slides deposited at the SAMC (one slide with the female holotype and one juvenile and one slide with one female voucher skin from barcode plate 06176H04) , one slide with one female and one juvenile deposited at the MNHN .

Description. Length. 0.9–1.2 mm. Body plump. Pigmentation uniformly bright red when alive and in ethanol ( Fig. 1 ).

Granulation fine and regular. Diameter of a granule same as socket of the tergite S-chaetae. Paurochaetotic and moderately heterochaetotic.

Antennae ( Figs 2 , 3A ). Antennae short, about 3/4 as long as head. Ant. I, II and III with 7, 12 and 17/18 ordinary chaetae respectively, some very slightly serrated. Ant. III and IV fused dorsally with clear ventral separation. Sensory organ on third antennal segment complete, with two small internal globular S-chaetae surrounded by two tapering, blunt, subequal guard S-chaetae, and a ventral S-microchaeta. Ant. IV dorsally with long ordinary and mou-chaetae, of very similar morphology, thin, and hardly blunt apically; S-chaetae undistinguishable, possibly corresponding to the shortest dorsal chaetae; a small dorso-external thick S-microchaeta distally. Subapical organite “or” extremely minute. Apical bulb very large, irregular, trilobed. Ventral sensory rasp not differentiated.

Ocular plate ( Fig. 3B, C ). Ocelli 8 + 8, in black pigmented eyepatch. PAO round with 6-8 vesicles, arranged in a circle, approximately the same size as an ocellus.

Mouthparts ( Fig. 4A, B ). Buccal cone truncated. Mandibles absent. Maxilla head typical of the genus, globular, with five strong, apically rounded teeth and parallel striations proximally, a sixth one, very reduced, sometimes present basally. Labium with subequal chaetae.A, B, C, D, E, F, f, G and 5 lateral ones (a, b, c, d, e); rooted papillate chaeta L present; no x-papilla seen.

Dorsal chaetotaxy ( Figs 4C , 5A, B, C , 6 ). Dorsal macrochaetae of moderate length, straight, thick, sheathed, smooth, and slightly clavate on Abd. III to VI. Mesochaetae curved, non-sheathed, not clavate, smooth or slightly serrated. S-chaetae thinner, rather short, subequal, 0.45 as long as dorso-external macrochaetae on Abd. V. Chaetotaxy of head with asymmetries, chaetae a0 and an uneven chaeta at the level of d2 present. Th. II to Abd. V macrochaetae as 22/22223 per side. Th. I to Abd. V dorso-internal chaetae as 143/33332. Th. II to Abd. V S-chaetae as 2,2/2,1,1,1,1 per side, ms present laterally on Th. II, remote from S-chaeta. Position of S-chaetae 3,3/4,4,4,4,2. Thorax I with 3 + 3 chaetae. Th. II with (9+2S+ms) and Th. III with (8+2S) per side, chaetae a2 absent on Th. III. Abd. VI with 6 clavate chaetae and 7 or 8 acuminate chaetae, of which one anterior (a0) and one posterior (p0?) are unpaired.

Ventral chaetotaxy ( Figs 5D, E , 7B ). Chaetae smooth, thin and acuminate. Thoracic sternites without chaetae. Ventral tube with 2+2 distal and 1+1 postero-basal chaetae. Abd. II with 2+2 chaetae Ve, Abd. III with 6–7+6–7 chaetae Ve, Abd. IV with 6–7+6–7 chaetae VL and 7–8+7–8 chaetae Ve (with rare asymmetries). Furca and tenaculum absent, furcal rest with 4 microchaetae ( Fig. 5D ). Abd. V with 2+2 chaetae Ag and 4–5+4–5 chaetae VL, genital plate of female with 13–17 circumgenital microchaetae and 1+1 or possibly 2+2 eugenital microchaetae ( Figs 5E , 7B ). Male genital plate not observed. Anal region with 3 hr chaetae on each valve and 14 + 14 Ve chaetae, of which 1-2 + 1-2 are macrochaetae.

Legs ( Fig. 7A ). Claw without internal or lateral tooth. Tibiotarsi I, II, III respectively with 19,19,18 chaetae (11,11,11 in the apical whorl and 8,8, 7 in the basal whorl, chaetae M present); among them, 4,4,4 thick and strongly clavate chaetae (of which 2,2,2 dorsal and 2,2,2 ventral). Femur I, II, III with 12, 12, 11 chaetae; trochanter I, II, III with 6, 6, 6 chaetae; coxae I, II, III with 3, 6, 7 chaetae respectively.

Ecology. Setanodosa jacquesi sp. nov. is only know from a single location in the Cape region. It has been collected floating on water in a rock pool.

Etymology. We dedicate this species to its collector, Jacques Scheepers.

Barcoding results. The mitochondrial genome of Brachystomella parvula has been recently published by Jiang et al. (2019). We give here the first COI sequences published for different genera, species and populations of the family, including two Setanodosa and two Brachystomella Agren, 1903 species ( Fig. 8 ). Between-species divergences are high, ranging from 22 to 26 %, i.e. similar to or even higher than between-species divergences observed in other families according to available literature ( Porco et al. 2012, Sun et al. 2018). Divergences within species are low (0-1.8 %). As expected, S. jacquesi sp. nov. is well separated from the sub-Antarctic species S. steineni , the only other species of the genus which has been barcoded so far.

Figures

FIGURE 1. Setanodosa, habitus in ethanol. A, a reddish undescribed species from Sutherland, Northern Cape, South Africa; B, Setanodosa jacquesi sp. nov. Scales: 0.5 mm.

FIGURE 2. Setanodosa jacquesi sp. nov. Antenna, dorsal side of segments III and IV. Scale: 10 µm.

FIGURE 3. Setanodosa jacquesi sp. nov. A, Apical bulb of Ant. IV; B, ocelli; C, PAO and external ocelli. Scales: 10 µm.

FIGURE 4. Setanodosa jacquesi sp. nov. A, maxilla; B, labium; C, dorsal chaetotaxy of head (x, chaeta absent asymmetrically). Scales: A, 10 µm; B, 20 µm; C, 50 µm.

FIGURE 5. Setanodosa jacquesi sp. nov. A, Dorso-external S-chaeta of Th. II; B, Dorso-internal macrochaeta of Abd. VI; C, Dorso-external (De) and dorso-lateral (DL) chaetal groups of Abd. I; D, furcal area; E, female genital plate. Scales. A,B,C, 10 µm; D,E, 20 µm.

FIGURE 6. Setanodosa jacquesi sp. nov. Tergite chaetotaxy. A, Th. I-III; B, Abd. II-VI (x, chaetae absent asymmetrically). Scale: 100 µm.

FIGURE 7. Setanodosa jacquesi sp. nov. A, Tibiotarsus of leg III; B, Ventral chaetotaxy of abdomen (Abd. IV: Ve group with a duplicated chaeta posteriorly). Scales: A, 20 µm; B, 100 µm.

FIGURE 8. Neighbor-joining K2P distance tree for COI of some Brachystomella and Setanodosa species (see Table 1 for locations).