Megalothorax zealanterolenis, Schneider & Minor & D’Haese, 2023

Schneider, Clément, Minor, Maria A. & D’Haese, Cyrille A., 2023, A new group of species of the genus Megalothorax (Collembola, Neelidae) with Gondwanan distribution, and introducing an open interactive identification key of Megalothorax species, Zootaxa 5228 (2), pp. 101-121 : 110-115

publication ID	https://doi.org/ 10.11646/zootaxa.5228.2.1
publication LSID	lsid:zoobank.org:pub:07D486F0-D44C-4F4B-B625-557442893DF2
DOI	https://doi.org/10.5281/zenodo.7541732
persistent identifier	https://treatment.plazi.org/id/01379830-FFF4-5076-E0E9-0970BD8DD156
treatment provided by	Plazi
scientific name	Megalothorax zealanterolenis
status	sp. nov.

Treatment

Megalothorax zealanterolenis View in CoL sp. nov.

Figs 6 View FIGURE 6 , 7 View FIGURE 7 , 8A, B View FIGURE 8 , 9E View FIGURE 9

Material examined. For all following material, name of locality, date of collection and name of collector: New Zealand, South Island, Nelson-Tasman region, Kahurangi National Park, Mt Arthur summit track, 27 January 2017, collected by M. Minor.

Holotype. Female on slide ( CSCOL _1327), 41.1967°S, 172.7312°E, 1096 m a.s.l., southern beech forest (mostly Fuscospora cliffortioides (Hook.f.) with some Lophozonia menziesii (Hook.f.) , in soil with litter and moss Hypnum cupressiforme Hedw. , sample MtAb_ T 1-1.

Paratypes. Four females and one male on three slides ( CSCOL _1326, 1328, 1329), same data as the holotype, sample MtAb_ T1-1 .

Other material. One female on slide CSCOL _1330, 41.1966°S, 172.7315°E, 1091 m a.s.l., southern beech forest ( F. cliffortioides ), in soil with litter, sample MtAb_ T 1-4. A juvenile on slide CSCOL _1331, 41.1965°S, 172.7319°E, 1082 m a.s.l., southern beech forest (mostly F. cliffortioides with some F. fusca ), in soil with litter, sample MtAb_ T 1-5. A female on slide CSCOL _1332, 41.1962°S, 172.7322°E, 1084 m a.s.l., southern beech forest (mostly F. cliffortioides with some F. fusca ), in soil with litter, sample MtAb_ T 1-6. Three juveniles, three males, one female and one adult (sex indet.) on eight slides CSCOL _1333–1340, 41.1923°S, 172.7354°E, 1066 m a.s.l., southern beech forest ( F. cliffortioides with some L. menziesii ), in soil with litter, sample MtAb_ T 2-1. Four juveniles, two females on three slides CSCOL _1341–1343, 41.1923°S, 172.7354°E, 1066 m a.s.l., southern beech forest ( F. cliffortioides with some L. menziesii ), in soil with litter under liverwort Bazzania involuta (Mont.) Trevis. , sample MtAb_ T 2-2. Two females on a slide CSCOL _1345, 41.1920°S, 172.7359°E, 1077 m a.s.l., southern beech forest ( F. cliffortioides with some L. menziesii ), in soil with litter, sample MtAb_ T 2-5. Two females on two slides CSCOL _1346, 1347, 41.1901°S, 172.7397°E, 1018 m a.s.l., mixed southern beech forest ( F. cliffortioides with some Fuscospora fusca (Hook.f.) and L. menziesii ), in soil with litter, sample MtAb_ T 3-1. One female on slide CSCOL _1348, 41.1901°S, 172.7397°E, 1018 m a.s.l., mixed southern beech forest ( F. cliffortioides with some F. fusca and L. menziesii ), in soil and litter with moss Dicranoloma robustum (Hook.f. & Wilson) Paris , sample MtAb_ T 3-2. One female on slide CSCOL _1349, 41.1902°S, 172.7399°E, 1024 m a.s.l., mixed southern beech forest ( F. cliffortioides with some F. fusca ), in soil and litter with moss D. robustum , sample MtAb_ T 3-3. Two juveniles, one adult (sex indet.) on three slides ( CSCOL _1350–1352), 41.1902°S, 172.7400°E, 1025 m a.s.l., southern beech forest ( F. cliffortioides with some F. fusca ), in soil and litter with moss D. robustum , sample MtAb_ T 3-4. One male, one female on two slides ( CSCOL _1353, 1354), 41.1903°S, 172.7409°E, 1013 m a.s.l., mixed southern beech forest ( F. cliffortioides with some F. fusca and L. menziesii ), in soil and litter with moss Ptychomnion aciculare (Brid.) Mitt. , sample MtAb_ T 3-6.

Material deposit. The holotype ( CSCOL _1327) and two paratypes (a female and a male, CSCOL _1328, CSCOL _1329) will be deposited at the Museum of New Zealand Te Papa Tongarewa, Wellington, New Zealand . Three female paratypes ( CSCOL _1326) will be deposited at the Senckenberg Museum für Naturkunde, Görlitz, Germany .

Diagnosis. Whitish in ethanol, labrum a1 chaetae with bifurcate tip, maxillary palp with an internal bifurcate hair, basomedian and basolateral fields of labium each with 1 + 1 chaetae, secondary granulation limited to the abdominal I – IV tergites, on the abdomen s-chaetae s2 elongated and tubular, s3 absent, tenaculum with 4 + 4 teeth, posterior lamellae of the mucro moderately enlarged, internal lamella serrated, external lamella smooth and waved or with weak teeth.

Description. General aspect. Habitus and segmentation typical of the genus. Length from labrum to anus: up to 400 µm. Specimens whitish (in 96% ethanol). All typical chaetal types of the genus are accounted for, without any remarkable development.

Integument. Secondary granulation restricted to the dorsal part of the abdominal area except Abd. VI, similarly to M. anterolenis sp. nov. Head channels connection with linea ventralis circular, integumentary channels not precisely analysed, apparently limited to the dorsal part of the head.

Sensory fields and wax rods. Same observation as in M. anterolenis . sp. nov., see Fig. 6A,B View FIGURE 6 .

Head chaetotaxy. Postero-dorsal chaetae without remarkable thickening, stronger than antero-dorsal chaetae. Number of chaetae: 12 + 12 in the postero-dorsal region, 9 + 9 and 2 unpaired in the antero-dorsal region, 2 + 2 in the antero-lateral region ( Fig. 6B View FIGURE 6 ). Ventrally, 3 + 3 chaetae in the sub-labial region ( Fig. 8B View FIGURE 8 ).

Labium. Basomedian fields of labium with 1 + 1 chaetae, basolateral fields of labium with 1 + 1 chaetae on a small papilla. Labial palps ordinary.

Labrum. Same observations as in M. tasmanterolenis .

Other mouthparts. Same observations as in M. tasmanterolenis , left mandibula figured in Fig. 6C View FIGURE 6 .

Antenna. Ant. I with one chaeta. Ant. II with four chaetae, the anterior one much stronger than the three others ( Fig. 6D View FIGURE 6 ). Ant. III with 10 chaetae, and five S-chaetae including S1–S4 from the sensory organ and Sb4; S2 and S3 small but clearly protruding from the cupule; without perceptible ornamentation in light microscopy; S1 and S4 appeared well contrasted with perceptible ornamentation rings. Ant. IV with five chaetae (X present), and 11 Schaetae (Sb1–3, Sb 5, Sa 1-5, Sx and Sy; Sa2 notably enlarged and with a clearer appearance than the others common S-chaetae (Sa and Sb); 2 apical and subapical rods (a, sa) present ( Fig. 6D View FIGURE 6 ).

Thoracic and abdominal tergites. As in Fig. 6A View FIGURE 6 , same observations as in M. anterolenis sp. nov., but with schaetae s3 absent and s-chaetae s2 elongated. Pseudopores not studied, 3 + 3 τ-chaetae could be seen (the others to be considered not studied).

Abd. VI. Ordinary, with nine chaetae on tergites, a small chaetae on each anal valves. Sternites chaetotaxy not studied.

Genital plate. Female with 2 + 2 chaetae, male not studied.

Abd. IV sternites. With 2 + 2 usual neosminthuroid chaetae and 2 + 2 ordinary chaetae, the external chaetae much shorter than the internal ones ( Fig. 7A View FIGURE 7 ).

Abdominal appendages. Manubrium with 2 + 2 posterior chaetae. Dens ordinary: basal part of dens with 1 + 1 posterior chaetae, apical part of dens with 1 + 1 posterior chaetae and 7 + 7 small spines. Apex of the five anterior spines tapering to a filament. Mucro elliptical, with wide lamellae; five to seven teeth on the external posterior lamella, internal posterior lamella smooth and waved, sometimes with weak teeth ( Figs 7H – J View FIGURE 7 , 9E View FIGURE 9 ). Ventral tube with 2 + 2 apical chaetae, retinaculum with 4 + 4 teeth.

Legs. Chaetal composition on legs (subcoxa 1, 2, coxa, trochanter, femur and tibiotarsus): leg I, 1, 0, 1 (at least), 2, 8, 12 chaeta(e); leg II, 1, 1, 1, 3, 8, 12 chaeta(e); leg III, 2, 1, 1, 4, 8, 10 chaeta(e). Claws ordinary, as in Fig. 7E, F, G View FIGURE 7 .; with basal lamellae la and lp short.

Differential diagnosis. Most similar to M. tasmanterolenis sp. nov., the two species can be distinguished from the shape of s-chaetae s2 on the abdomen.

Name etymology. Derived from the name of M. anterolenis sp. nov. combined with the country of discovery ( New Zealand).

Ecology. The new species was found in soil and litter of montane southern beech forests in the subalpine zone (ca. 1000–1100 m above sea level) of Mt Arthur (1795 m) in the Kahurangi National Park, Nelson-Tasman region of the South Island of New Zealand. The Mt Arthur sites vegetation is dominated by montane forests of southern beech, mostly mountain beech Fuscospora cliffortioides (Hook.f.) Heenan & Smissen , some red beech Fuscospora fusca (Hook.f.) Heenan & Smissen and silver beech Lophozonia menziesii (Hook.f.) Heenan & Smissen , small shrubs and mosses. The soils in sampled plots were cold (7–8 deg Celsius) and wet (21–44% volumetric moisture content) in January (mid-summer).

The new species was widespread in samples from Mt.Arthur and locally found in high abundance (mean density 2,800 ind. m-2, max 10,800 ind. m-2). The new species may be geographically restricted, as it was not observed in subalpine beech forests of two other mountains sampled in the same region.