Mastigoceras handschini Rodrigues, Souza & Bellini, 2024

Rodrigues, Iandra Vitória Bezerra, de Souza, Paolla Gabryelle Cavalcante, Nunes, Rudy Camilo, Nunes Godeiro, Nerivânia & Bellini, Bruno Cavalcante, 2024, A century later: a new species of Mastigoceras Handschin, 1924 (Collembola, Orchesellidae), with morphological and systematic updates on the genus, ZooKeys 1217, pp. 79-100 : 79-100

publication ID	https://doi.org/ 10.3897/zookeys.1217.132351
publication LSID	lsid:zoobank.org:pub:2D9F30D6-A5A6-45EA-8BCD-3BE4FA3D7E71
DOI	https://doi.org/10.5281/zenodo.14014971
persistent identifier	https://treatment.plazi.org/id/7E0F9978-400C-49EA-8B0B-03C2688EFF10
taxon LSID	lsid:zoobank.org:act:7E0F9978-400C-49EA-8B0B-03C2688EFF10
treatment provided by	ZooKeys by Pensoft
scientific name	Mastigoceras handschini Rodrigues, Souza & Bellini
status	sp. nov.

Treatment

Mastigoceras handschini Rodrigues, Souza & Bellini sp. nov.

Figs 3 View Figure 3 , 4 View Figure 4 , 5 View Figure 5 , 6 View Figure 6 , 7 View Figure 7 , Table 1 View Table 1

Type material.

Holotype: Brazil • 1 male, 1.65 mm; Piauí state, Pedro II municipality, Urubu-rei waterfall ; 4 ° 19 ' 37.90 " S, 41 ° 27 ' 45.89 " W; 06 Nov. 2019; E. P. Santos leg.; soil surface / entomological aspirators; GenBank: PP 960563; deposited at CC / UFRN, Mastigoceras handschini GoogleMaps . Paratypes: • 4 females and 4 males in slides, same data of holotype GoogleMaps • 2 juveniles in slides, same data as holotype, except 10 Oct. 2019, pitfall traps GoogleMaps . • 4 females and 4 juveniles in slides, same data of holotype, except 24 May 2019 GoogleMaps . All material deposited at CC / UFRN.

Diagnosis.

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 (S 1); labial basomedian field m 1 chaeta usually smooth, rarely ciliate; Th. II a series with 17 mac, 15 on the collar plus a 2 and a 5; Abd. III with one internal mac (a 2?); 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.

Description.

Body length (head + trunk) of the type series ranging from 1.32 to 2.22 mm (n = 10). Holotype body length 1.65 mm. Specimens with dark purple pigment on antennae, on head as lateral bands and with an anterior spot between the antennal bases, on trunk as a lateral band from Th. II to Abd. V (sometimes missing on Abd. II) and some dorso-internal spots and / or stripes on the segments; and on femora and tibiotarsi as 1 and 2 axial stripes, respectively; furca lacking pigments (Fig. 3 View Figure 3 ). Hyaline ciliate fusiform scales present on dorsal anterior region of Th. III – Abd. III, rarely on Th. II posterior region (only in two specimens) (Figs 2 View Figure 2 , 4 D View Figure 4 , 6 H View Figure 6 ), scales absent on head and Abd. IV – VI; dorsal head and trunk covered by plentiful ciliate secondary mic.

Head (Figs 4 A, B View Figure 4 , 5 View Figure 5 ). Antennae 3–4 × longer than body length, with five segments (Ant. I subdivided), Ant. IV and III apparently fused in most specimens, possibly due to antennal regeneration. Antennal ratio Ant. Iab – IV of one paratype: 1: 4: 30: 5.6: 43.3 (Ant. III broken, basal part lost). Ant. IV long and annulated, with at least three types of chaetae: blunt sensilla, acuminate sensilla and ciliate chaetae, with a prominent subapical pin projection (Fig. 5 A View Figure 5 ). Ant. III long and annulated, apical sense organ with two sensory rods, three guard sensilla (one of them smaller and blunt) and at least five extra surrounding sensilla (Fig. 5 B View Figure 5 ). Ant. II flexible, weakly annulated; Ant. I subdivided, with several small smooth mic at the apex of segment Ia (Fig. 4 A View Figure 4 ), Ant. Ib with six slightly ciliate stiff mac (Fig. 5 C View Figure 5 ). Labral apical papillae absent, labral ornamentation as in Fig. 5 D View Figure 5 . Four prelabral smooth chaetae, labral chaetotaxy formula as 5 (p), 5 (m), 4 (a), all smooth, a 1 larger than a 2 (Fig. 5 E View Figure 5 ). Clypeal chaetae unclear. Labial palp with five proximal subequal chaetae, labial papillae short, formula of papillae and guards as: H (2), A (0), B (5), C (0), D (4), E (5) + a finger-shaped lateral process, not reaching the base of papilla E (Fig. 5 F View Figure 5 ). Labial basomedian and basolateral fields chaetae formula as a 1 – 5 / m 1 – 2 el 1 – 2, m 2, e and l 1 always smooth, m 1 and l 2 usually smooth, rarely ciliate (only in 2 specimens) or m 1 absent, r chaeta absent (Fig. 5 F View Figure 5 ). Maxillary outer lobe apical appendage slightly longer than the blunt basal chaeta, sublobal plate with four chaetae-like appendages, the three internal blunt, oral fold with two chaetae (Fig. 5 G View Figure 5 ). Ventral post-labial chaetotaxy with ~ 100 ciliate and 11 or 12 smooth chaetae, cephalic groove with five ciliate and two or three smooth chaetae surrounding it (Fig. 5 H View Figure 5 ). Eyes 8 + 8, A – B larger, C – F subequal, and G – H smaller than others, with four or five interocular mes (r present or absent); PAO as a small circular fold next to A lens, anterior pseudopore next to the antennal base (Figs 4 B View Figure 4 , 5 I View Figure 5 ). Dorsal chaetotaxy with five antennal (An 1 a – 3 a), one sutural (S 1), three postoccipital anterior (Pa 1?, Pa 3, Pa 5), two post-occipital medial (Pm 1, Pm 3), three post-occipital posterior (Pp 1, Pp 3, Pp 5), and three post-occipital external (Pe 2, Pe 3, Pe 5) mac, dorsal head mic and mes homology as in Fig. 5 I View Figure 5 .

Trunk (Figs 4 C – E View Figure 4 , 6 View Figure 6 ). 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 – Abd. IV central mac formula, excluding the mesothoracic collar, as: 5, 3 | 1, 1–2, 1, 3–4; lateral mac formula as 1, 0 | 0, 1, 2, 0; bothriotricha formula as 0, 0 | 0, 2, 3, 2 (Fig. 6 A – G View Figure 6 ). Th. II with 17 anterior mac, a 2 and a 5 detached from the anterior collar, more posteriorly displaced (Fig. 6 A View Figure 6 ). Abd. I p 6? as a fan-shaped modified chaeta (Figs 4 C View Figure 4 , 6 C View Figure 6 ). Abd. III with one internal mac (a 2?) (Figs 4 D View Figure 4 , 6 E View Figure 6 ); Abd. IV T 3 as a finger-shaped chaeta (Figs 4 D View Figure 4 , 6 F View Figure 6 ). Abd. V lateral chaetae as mes or bothriotricha-like chaetae (Figs 6 G View Figure 6 ). Detailed homology of the main dorsal trunk chaetae presented in Fig. 6 View Figure 6 . Ratio Abd. III – IV in the midline of the holotype as: 1: 1.27.

Trunk appendages (Figs 4 F View Figure 4 , 7 View Figure 7 ). Trocantheral organ with 26–31 spine-like smooth chaetae (Fig. 7 A View Figure 7 ). Tibiotarsus III with one smooth distal chaeta near the unguiculus, pretarsus with one posterior and one anterior short chaetae; ungues with four inner teeth: two paired basal, one unpaired medial and one reduced unpaired apical; lateral and external teeth present; unguiculi lanceolate, with the postero-external lamella with a small proximal tooth; tenent hairs slightly ciliate and capitate (Fig. 7 B View Figure 7 ); empodial complex of leg III ratio of smooth chaeta, unguiculus, unguis and tenent-hair of holotype as 1: 1: 1.7: 2.2. Ventral tube anterior side with 14 or 15 ciliate chaetae plus one distal mac (Fig. 7 C View Figure 7 ); posterior side with at least 64 ciliate and eight smooth chaetae in total (Fig. 7 D View Figure 7 ); lateral flap with ~ 4 ciliate and 26 smooth chaetae (Fig. 7 E View Figure 7 ). Tenaculum rami with four teeth, corpus without chaetae (Fig. 7 F View Figure 7 ). Manubrium dorsally with 1 + 1 or 2 + 2 long bothriotricha-like chaetae (Fig. 4 F View Figure 4 ). Manubrial plate with three pseudopores and 5–7 chaetae (Fig. 7 G View Figure 7 ). Dens without spines. Mucro bidentate, apical tooth larger than basal one, mucronal spine reaching the apex of basal tooth (Fig. 7 H View Figure 7 ). Ratio manubrium: mucrodens of the holotype as 1: 1.88.

Results of COI species delimitation.

Comparing the whole mitochondrial COI gene of Mastigoceras handschini sp. nov. with M. camponoti , the sequence length is the same in both species, with 1539 bp. However, the p-distance (number of base differences per site from between sequences) is 17 %, and the K 2 P interspecific distance between them is 19.2 %, enough to separate them as independent species. Considering the partial COI (658 pb), the p-distance is 16.3 %, and the K 2 P interspecific distance between them is 18.6 %. As previously discussed, earlier studies have found that the interspecific distance for Collembola species usually ranges from 16.35 % to 24.55 %. ( Porco et al. 2012; Yu et al. 2016; Sun et al. 2018).

Etymology.

The species honors Dr. Eduard Handschin (1894–1962), who described the genus Mastigoceras and its single species, M. camponoti .

Distribution and habitat.

Mastigoceras is only found in Brazil, with previous records from the Amazon and Atlantic forests and the Caatinga biomes ( Cassagnau 1963; Cassagnau and Oliveira 1992; Mendonça et al. 2009; Bellini 2014; Cipola et al. 2019; Zeppelini et al. 2024). Handschin’s (1924) original description does not list the municipality where the type material was sampled, mentioning only “ south of Minas ” (southern region of Minas Gerais state). Thus, it is unclear if his specimens of Mastigoceras were previously sampled from the Cerrado biome. The record of Mastigoceras handschini sp. nov. from a transitional zone between the Caatinga and Cerrado biomes represents the second record of the genus from the northeastern region of Brazil, with M. camponoti having been previously recorded from the state of Ceará ( Bellini 2014; Zeppelini et al. 2024).

The new species was found at “ Cachoeira do Urubu-Rei ” (Urubu-Rei waterfall), located in the rural region of Pedro II municipality, Piauí state, Brazil. The region has minimum of 23.1 ° C and maximum temperatures of 29.3 ° C, with a hot and humid tropical rainy climate classified as “ As ” according to the Köppen-Geiger system ( Kottek et al. 2006). The collection site is located at an altitude of 603 m above sea level and is covered by riparian forest vegetation following a perennial watercourse, featuring evergreen broadleaf plants, bryophytes, and pteridophytes. Unlike the type material of M. camponoti , which was sampled from ant nests, specimens of Mastigoceras handschini sp. nov. were sampled above the leaf litter using pitfall traps and entomological aspirators (Fig. 8 View Figure 8 ).

Remarks.

We could revise one female specimen of M. camponoti from the southern region of Minas Gerais state, Mariana municipality, but the quality of the slide prevented us from redescribing it this time and draw further comparisons between the species. Even so, we could confirm its dorsal macrochaetotaxy is mostly the same of Mastigoceras handschini sp. nov., with the exception of the anterior collar on Th. II. The morphology of this specimen matches Mari-Mutt’s 1980 a observation of M. camponoti , who stated Mastigocerini has nine or ten mac in the collarette ( Mari-Mutt 1980 a, pg. 457). Our revised specimen has ten anterior mac on the collar plus a 2 and a 5 more posteriorly ¸ totaling 12 mac on Th. II a series. We could observe in M. camponoti the distribution of body scales, also present on head (only a few were observed), as noted by Mari-Mutt (1978), and on anterior and medial regions of Th. II (tergum densely covered by scales). Other features which would be useful to compare the species like ventral tube, manubrial plate and trochanteral organ chaetotaxy could not be clearly analyzed due to the slide quality.

Mastigoceras handschini sp. nov. is remarkably similar to M. camponoti in color pattern, size of antennae and overall chaetotaxy. However, it differs from the latter species especially by: scales absent on dorsal head, Th. II anterior and medial regions, and Abd. IV (vs. present in M. camponoti ), Th. II a series with 17 mac, including the collar (up to 12 in M. camponoti ), Abd. IV with a finger-shaped T 3 (absent in M. camponoti ), and Abd. VI not papillate in males (vs. with an apical papilla in M. camponoti ). Details on Mastigoceras species comparative morphology and their distribution are summarized in Table 1 View Table 1 . For further discussion on the genus and tribe morphology, see the next section.