Eduard Handschin springtail (Mastigoceras handschini), a century after original description of Mastigoceras camponoti

NEWS - Researchers revisited the genus by describing a new species from Brazil, Eduard Handschin's springtail (Mastigoceras handschini Rodrigues, Souza & Bellini, sp. nov.), a century after the original description of Mastigoceras camponoti Handschin 1924 based on morphological descriptions combined with the use of DNA barcoding.

Mastigoceras Handschin 1924 is a monotypic genus of Orchesellidae that has only been recorded in Brazil. The systematic position of Mastigoceras has been debated and has been considered as a transitional form between Entomobryinae, Paronellinae and Orchesellidae.

Other opinions suggest part of Entomobryidae, tribe Mastigocerini (with no clear position within Orchesellidae) to as a group Heteromurinae, possibly as a sister group to Heteromurini.

Now researchers revisit Mastigoceras with an updated diagnosis for the genus and notes on Mastigocerini morphology, structural homology, and systematics. Complete mitochondrial Cytochrome Oxidase I (COI) sequences of the new species and Mastigoceras camponoti were obtained and compared.

Mastigoceras has fusiform small hyaline ciliate scales, without ribs, present at least in dorso-anterior Th. III–Abd. III, present or absent on dorsal head, Th. II, and Abd. IV; antennae, legs, ventral tube, tenaculum and furca scaleless.

Body also densely covered by secondary ciliate mic; dorsal macrochaetotaxy reduced. Antennae very long, 2–4× the body length; antennae with five segments, Ant. I subdivided, Ant. II stiff or weakly annulated, Ant. III–IV longer than other segments, annulated and whip-like; Ant. IV apical bulb absent. Eyes 8+8, PAO present.

Tergal sensilla and microsensilla formulae of Th. II–Abd. V as 1.1|0.3,3,+.9 and 1.0|1.0,1,0.0, respectively. Th. II anterior (a) series, including the collar, with up to 17 mac. Abd. IV less than 1.5× the length of Abd. III in the midline. Abd. VI of lazy short and rounded; of females long and conical.

Trochanteral organs variably developed. Tenaculum without chaetae. Manubrium dorsally with one or two bothriotrichum-like chaetae; dens crenulate, without spines; mucro bidentate with the basal spine.

M. handschini has a diagnosis with fusiform scales present on anterior region of Th. III–Abd. III, rarely on Th. II posterior region, scales absent on head and Abd. IV–VI; sutural cephalic series with one mac (S1); labial basomedian field m1 chaeta usually smooth, rarely ciliate; Th. II a series with 17 mac, 15 on the collar plus a2 and a5; Abd. III with one internal mac (a2?); Abd. VI of males without the apical papilla; trochanteral organ with 26–31 spine-like smooth chaetae; ventral tube lateral flap with ~ 4 ciliate and 26 smooth chaetae; manubrial plate with three pseudopores and 5–7 chaetae.

All mitochondrial COI genes of M. handschini and M. camponoti have the same sequence length of 1539 bp. However, the p-distance is 17% and the interspecific K2P distance is 19.2%, sufficient to separate the two as independent species. Considering the partial COI (658 bp), the p-distance is 16.3% and the interspecific K2P distance between them is 18.6%.

This new species honors Dr. Eduard Handschin (1894–1962) who described the genus Mastigoceras and its single species, M. camponoti. M. handschini was found in “Cachoeira do Urubu-Rei” located in the rural area of the municipality of Pedro II, Piauí state, Brazil.

Temperature 23.1-29.3°C, hot and humid tropical rain, elevation 603 m and covered by riparian forest vegetation that follows perennial watercourses with evergreen broadleaf plants, mosses and ferns. Unlike the M. camponoti samples that were taken from ant nests, M. handschini specimens were collected on leaf litter using traps.

Original research

Rodrigues IVB, de Souza PGC, Nunes RC, Nunes Godeiro N, Bellini BC (2024). A century later: a new species of Mastigoceras Handschin, 1924 (Collembola, Orchesellidae), with morphological and systematic updates on the genus. ZooKeys 1217: 79-100, DOI:10.3897/zookeys.1217.132351

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