Platynothrus palaciosii Villagomez & Heethoff 2024, sp. nov.
Creators: name: Villagomez, Fernando
name: Heethoff, Michael
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Arachnida
Sarcoptiformes
Crotoniidae
Platynothrus
Platynothrus palaciosii

description: Platynothrus palaciosii sp. nov.
(Figs. 1–9, 19–21)
Zoobank code: urn:lsid:zoobank.org:act: 3D74EAD3-BB1A-4AAE-A588-DDFFA94E792E
Genbank accession numbers: PP216472—PP216478.
Diagnosis. Sensillus short, clavate and radially barbed; interlamellar seta curved at base, smooth; lamellar seta longest of all prodorsal setae, barbed; rostral seta short, smooth; all notogastal setae long; with 12-15 pairs of genital setae, but usually 14; legs monodactylous.
Description. Measurements in µm inside brackets, n = 6. Length 780-810, width 435-460.
Integument. Body color brown to dark brown or even black, debris attached mainly in central prodorsum and between caudal notogastral setae (Figs. 19-20). Cuticular porosity present in epimeral plates towards trochanters, subcapitulum and prodorsum, where overlays with small foveolae (Fig. 21). Notogaster smooth with weakly punctate surface. Articulating cuticle between epimeres and genital plates with granular ornamentation.
Prodorsum (Figs. 1, 3, 20-21). Two small central concave regions and two posterolateral elevations well defined between bothridium and notogaster, these elevations extend around bothridium on external side and connect with central protruding region. Supra anterior contours between small, but well discernible, lamellar seta apophysis, folded inwards, giving appearance of a transverse ridge. Below lamellar apophysis, without foveolate pattern, only cuticular porosity present, rostrum rounded. Sensillus (ss) short (53), inserted in slightly protruding bothridium, with last third of external stalk clavate, ornamented with inner core of radial small barbs (Fig. 21); exobothridial seta (ex) present, very fine and bristle-like (9), smooth; interlamellar seta (in) curved at base, smooth; medium sized (85), reaching about halfway to lamellar apophysis; lamellar seta (le), longest of prodorsal setae (105), barbed; mutual distance of pair le -le approximately twice that of in -in; rostral seta (ro) short (28), smooth, usually curved.
Gnathosoma (Figs. 2, 4, 5). Subcapitulum subtriangular, covering approximately half length of chelicera, bearing one short hypostomal seta (6), and two genal setae, seta m (15) longer than seta a (6). Chelicera with three and four teeth in fixed and mobile digits respectively, cha seta (46) slightly longer than chb (34), both barbed, Trägårdh’s organ wide and long. Palp short (60-64), only seta sup from femora barbed, all others setiform and smooth, palpal chaetotaxic formula from femur to tarsus: 1-0-3-7(1).
Notogaster (Figs. 1-2). Flattened, dorsal outline of anterior region less curved and narrower than posterior, with pair of wide central ridges extending slightly posterior to level of opistonothal gland opening (gla), arched medially; with second pair of thin ridges between central ridges and lateral margin, extending posterior to h 1 seta insertion; with an oval concavity of notable size on caudal region, usually with some debris attached. Fifteen pairs of smooth notogastral setae, medium sized (Table 2) and relative thick, anterior central setae c 1, c 2, d 1, d 2, smaller than all others, lateral setae e 2 and cp longest; opisthonotal gland opening slightly anterior to f 2. Lyrifissure ih positioned medio-ventrally, near level of second aggenital seta, ips with postero-ventral position, slightly anterior to level of third adanal seta. Lyrifissures ip, im and ia located in pleural region, only visible in lateral position and, therefore, not illustrated herein.
Epimeral region (Fig. 2). Epimeral setae formula as usual in this group (3-1-3-4). Setae 1a, 2a, 3a, 4a short and spiniform (<10); 1b and 1c short and setiform; (12-14), 3b (18), 3c (20), 4c (26), and 4d (26), longer and setiform, 4b not visible. Setae 3c and 3b closely inserted, separated from 3a by three times their mutual distance.
Anogenital region (Fig. 2). 12-15 (usually 14) pairs of long genital setae (38-42), inserted in a row medial to submarginal carina, two pairs of long, thin aggenital setae (50), inserted in anterior and posterior part of genital plate respectively; three pairs of short adanal setae (13-16) present; two pairs of minute anal setae located in anterior half of anal plate; Lyrifissure ian present, midway between seta an 2 and anterior edge of plate; iad at similar level, anterior to ad 3.
Legs (Figs. 6-9). All legs monodactylous. With mixture of barbed and smooth setiform setae, some spiniform setae, and less common foliose setae. Chaetotaxic formulae from trochanter to tarsus of legs I to IV (solenidia in brackets): I. 1-9-5(1)-5(2)-25(3), II. 1-9-5(1)-5(1)-23(3), III. 5-5-3(1)-4(1)-21. IV. 1-4-3(1)-4(1)-21. Solenidia from genu to tibia coupled with one dorsal seta. Leg I genu with medium sized solenidion (σ) inserted dorsally; tibia with two solenidia of different size, φ 1 long and dorsal, φ 2 small and lateral; tarsus with 3 solenidia of similar size, one dorsal and two lateral, famulus (ε) dorsally inserted and setiform, medium sized. Leg II genu with small solenidion (σ) protected by foliose d seta; tibia with medium sized solenidion (φ) dorsally, associated with spiniform d seta; tarsus with three solenidia, two dorsal similar in size, one lateral slightly longer. Leg III and IV genu and tibia with one small solenidion σ, associated with d barbed seta.
DNA intraspecific variation. Seven specimens of Platynothrus palaciosii sp. nov. from the same population were subjected to amplification and sequencing of the COX-1 mitochondrial marker. Nucleotide pairwise distances from 626 nucleotides revealed an intraspecific difference (K2P) ranging from 0% to 2.15% (Table 3).
Type material. Specimens in plastic vials with 75% ethanol were deposited in the collection of the Senckenberg Museum für Naturkunde Görlitz, Germany, in Mesofauna / Oribatida section. Holotype female with catalog number DNR 66729, Santiago Comaltepec, Oaxaca, México. 27.02.2022. Coordinates, 17.588906, -96.399861. Montane cloud forest. Near sendero el Relámpago. Litter samples, Jair Paéz Col. Eight more females paratypes with the same data with catalog number DNR 66730.
Additionally, seven female paratype specimens with the same data in slides were deposited in the Colección de Collembola de México y Ácaros Edáficos, Facultad de Ciencias, Universidad Nacional Autónoma de México, México, with catalog number FC-UNAM: LESM-AC:OR-002 to FC-UNAM: LESM-AC:OR-009. Information on the holotype also can be accessed on this collection with catalog number FC-UNAM: LESM-AC:OR-001, information of DNR 66730 paratypes are associated with catalog number FC-UNAM: LESM-AC:OR-019 to FC-UNAM: LESM-AC:OR-026, each record is accompanied by a photograph of the specimen.
Etymology. The species is named to honor Dr. José G. Palacios Vargas, for his notable contributions to the development of entomology and acarology in Mexico and South America. Following the rules and recommendations of Art. 31.1.1 of the International Code of Zoological Nomenclature, the specific epithet is a noun in genitive in accordance with the masculine gender of the genus.
Remarks. Among monodactylous species of Platynothrus, only five present a short and bacilliform sensillus, barbed lamellar seta and smooth rostral seta. This new species differs from P. ovatus (Kundu & Mondal) and P. praeoccupatus = Sigmonothrus quadristriatus (Chakrabarti & Kundu), both from India, in shape and size of lamellar and interlamellar setae, but mainly in the straighter dorsosejugal scissure in this species versus oval, and position of setae c 2, c 3, f 2 and h 1. This new species also resembles P. punctatus (L. Koch), P. quadristriatus (Hammer) and P. troendelagicus, in general body shape and dorsosejugal scissure, but differs in longer gastronotic setae, longer lamellar and interlamellar setae, and curvature of central ridges.
To date, this is the first species of this genus, and conceivably the entire Crotoniidae, exhibiting three solenidia on the tarsi of leg II. This trait, was consistently observed in supplementary legs of diverse specimens, thereby precluding developmental anomalies.
In this mite genus, species have demonstrated the presence of multiple haplotypes, showcasing intraspecific variation of COX-1 ranging from 0% to less than 3%. Heethoff et al. (2007) observed variations within seven “geographical clades” of P. peltifer below 2%, while Seniczak et al. (2022) reported 0% for P. troendelagicus and 2.62% for P. punctatus, with interspecific distances among other members of this genus reaching nearly 30%. In this new species, the maximum intraspecific distance was 2.15%, indicating the coexistence of several haplotypes within the same population and collecting date. This aligns with previously published data and offers further insights for studies on species delimitation.
description: Published as part of Villagomez, Fernando & Heethoff, Michael, 2024, Two new species of Platynothrus and Heminothrus (Oribatida: Crotoniidae) from Mexico, pp. 214-232 in Zootaxa 5453 (2) on pages 216-222, DOI: 10.11646/zootaxa.5453.2.3, http://zenodo.org/record/11233916