Megalothorax boerneri, Schneider & Panina, 2023

Schneider, Clément & Panina, Ksenia, 2023, Revision of Megalothorax incertus Börner, 1903 reveals it to be another widespread Palearctic species of the genus (Collembola, Neelidae), Zootaxa 5318 (4), pp. 474-488 : 480-484

publication ID	https://doi.org/ 10.11646/zootaxa.5318.4.2
publication LSID	lsid:zoobank.org:pub:10C3728D-B718-4074-AC83-142A98A88895
DOI	https://doi.org/10.5281/zenodo.8184065
persistent identifier	https://treatment.plazi.org/id/03FC6644-DC45-2C7A-FF79-FA446A54FA47
treatment provided by	Plazi
scientific name	Megalothorax boerneri
status	sp. nov.

Treatment

Megalothorax boerneri sp. nov.

Figs 5–7 View FIGURE 5 View FIGURE 6 View FIGURE 7 , 8C, D View FIGURE 8 ; Tables 1–2 View TABLE 1 View TABLE 2

Material examined. Holotype: female on slide (SMNG-APT-AA00023), France, Haute-Marne, Charmes, 10 Apr. 2011, 47.9262°N, 5.3420°E, mosses growing on a rock, leg. C. Schneider, original collection code: Fr. 021. GoogleMaps Paratypes: three females on slides (SMNG-APT-AA0024–26), same data as the holotype. All types deposited in the Apterygota collection of the Senckenberg Museum f̧r Naturkunde G ̂rlitz GoogleMaps .

Other material. Two females on slides (SMNG-APT-AA00027, 28), France, Hautes-Pyrénées, Saint-Lary-Soulan, 26 Jun. 2011, 42.8268°N, 0.3114°E, Mosses and litter on the side of a path, leg. C. Schneider, original collection codes: Fr. 031py, Fr. 033py GoogleMaps

Molecular data. One individual from Fr.021 (same data as holotype) and one individual from Fr.033py (Genbank accession number in Table 1 View TABLE 1 ). Vouchers have not been recovered.

Diagnosis. Colour whitish (in 96 % ethanol), connection of head channels with linea ventralis crossed, without channels on trunk, basomedian fields of labium with 3 + 3 chaetae, basolateral fields of labium with 2 + 2 chaetae, abdomen without β2; but β4 and ζ4 present, abdominal s-chaetae s3 present, only slightly larger than s2, 3 + 3 chaetae on Abd. IV sternite, retinaculum with 4 + 4 teeth, posterior lamellae of the mucro thin and serrated.

Description. General aspect. Habitus and segmentation typical of the genus. Length from labrum to anus: up to 400 µm. Colour whitish (in 96 % ethanol).

Integument. Secondary granulation present dorsally on the head ( Fig. 5A View FIGURE 5 ), the thoracic region, the abdominal region and Abd. VI sternite ( Fig. 7A View FIGURE 7 ). Integumentary channels limited to the lateral and posterior part of the head, cycling around the postero-lateral chaetae ( Fig. 5A View FIGURE 5 ); no anterior channel, connection with linea ventralis crossed. Channels absent on the trunk.

Sensory fields and wax rods. Ordinary distribution of sensory fields and wax rods secretory crypts: 2 + 2 wrc on head, 12 + 12 wrc on body; including the ones associated with the 6 + 6 sensory fields ( Fig. 6 View FIGURE 6 ). Sensory fields include the swollen inner chaetae, all globular: sf1–6: 0, 1, 3, 2, 1, 1. wrc5 and 6 separated from sf5 by ~ 4 granules ( Fig. 6 View FIGURE 6 ).

Head chaetotaxy. Number of chaetae: 12 + 12 in the postero-dorsal region, 10 + 10 and 2 unpaired in the antero-dorsal region, 1 + 1 in the antero-lateral region ( Fig. 5A View FIGURE 5 , 8C View FIGURE 8 ). With 7 + 7 postero-dorsal chaetae thickened ( Fig. 5A View FIGURE 5 ), anterior chaetae short and ordinary ( Fig. 5A View FIGURE 5 ). Ventrally with 3 + 3 post-labial chaetae sub-equally sized.

Labium. Basomedian fields of labium with 3 + 3 chaetae, basolateral fields of labium with 2 + 2 chaetae ( Fig. 5B View FIGURE 5 ). Labial palps ordinary, as is Fig. 5B View FIGURE 5 .

Labrum. Chaetae a1, a2 with external teeth, a1 with apical outward curvature ( Fig. 5C View FIGURE 5 ).

Other mouthparts. Oral fold with 2 + 2 chaetae ( Fig. 5D View FIGURE 5 ). Maxilla outer lobe with two chaetae (apical and basal), sublobal plate with a hair ( Fig. 5D View FIGURE 5 ). Maxilla and mandibula as in Fig. 5E, F View FIGURE 5 .

Antenna. As in Fig. 5G View FIGURE 5 . Ant. I with one chaeta. Ant. II with four chaetae, the anterior one stronger than the three others. Ant. III with 9 chaetae and the four S-chaetae S1–S4 from the sensory organ; S2 and S3 clearly protruding from the cupule; all S1–S4 rather indistinct in our preparations. Ant. IV with six ordinary chaetae (including X) and 10 + 2 S-chaetae (Sb1–5, Sa1–5, Sx and Sy), Sb3 implanted basally, slightly above S2 and S3 of Ant. III. Organite (Or) small.

Thoracic tergites. As in Fig. 6 View FIGURE 6 . Pseudopores and τ-chaetae indistinct, not studied. Th. II with 12 + 12 chaetae and 1 + 1 s-chaetae s1. Th. III with 10 + 10 chaetae, a5 slightly stronger than a6, p4 close to wrc2. Diagram of chaetotaxy provided in Fig. 8D View FIGURE 8 .

Abd. I–V tergites. With 19 + 19 ordinary chaetae, 2 + 2 globular s-chaetae (s2, s3) with s3 slightly bigger than s2; chaetae β2 absent ( Figs 6 View FIGURE 6 , 8D View FIGURE 8 ).

Abd. VI. Tergite with 4 + 4 and 1 unpaired chaetae ( Fig. 7A View FIGURE 7 ). Each anal valve with one chaeta ( Fig. 7A View FIGURE 7 ). Sternite with 7 + 7 chaetae, the two axial pairs strongly curvated ( Fig. 7A View FIGURE 7 ).

Genital plate. Female with 3 + 3 chaetae ( Fig. 7A View FIGURE 7 ). Male unknown.

Abd. IV sternite. With 2 + 2 usual neosminthuroid chaetae, 3 + 3 ordinary chaetae and 1 + 1 small lobes ( Fig. 7A View FIGURE 7 ).

Abdominal appendages. Manubrium with 1 + 1 posterior chaetae ( Fig. 7B View FIGURE 7 ). Dens ordinary, as in Fig. 7B View FIGURE 7 . Mucro with thin lamellae, with ~10–12 teeth on each posterior lamellae ( Fig. 7B View FIGURE 7 ). Ventral tube with 2 + 2 apical chaetae ( Fig. 7C View FIGURE 7 ), retinaculum with 4 + 4 distinct teeth.

Legs. Chaetal composition on each legs subcoxa 1, 2, coxa, trochanter, femur and tibiotarsus: leg I—1, 0, 1, 3, 7, 12 chaeta(e) ( Fig. 7D View FIGURE 7 ); leg II—1, 1, 1, 3, 8 and 12 chaeta(e) ( Fig. 7E View FIGURE 7 ); leg III—2, 1, 1, 4, 8 and 11 chaeta(e) ( Fig. 7F View FIGURE 7 ). Claw as in Fig. 7G–J View FIGURE 7 , ordinary, subequal in length. Basal and posterior auxiliary lamellae of unguis well developed, anterior crest indistinct. Basal lobe of unguiculus not or feebly protruding.

Affinities. The most similar species are M. perspicillum , M. incertus sensu nov. and M. laevis . The differential diagnosis is provided in Table 2 View TABLE 2 . Also see the updated interactive key of the Megalothorax species of the world ( Schneider 2022).