Cyphoderus equidenticulati, Nunes & Bellini, 2018

Nunes, Rudy Camilo & Bellini, Bruno Cavalcante, 2018, Three new species of Entomobryoidea (Collembola: Entomobryomorpha) from Brazilian Caatinga-Cerrado transition, with identification keys to Brazilian Cyphoderus, Pseudosinella and Trogolaphysa species, Zootaxa 4420 (1), pp. 71-96 : 72-79

Cyphoderus equidenticulati sp. nov. Nunes & Bellini

Figs 1‒20

Type material. Holotype female on slide, Brazil, Piauí State, Piracuruca municipality, Parque Nacional de Sete Cidades (04°05’56.94”S; 41°42’33.42”W), Caatinga (transitional zone between Caatinga and Cerrado biomes), 12‒14.v.2015, R.C. Nunes coll. Paratypes on slides, one female and one juvenile, same data as holotype. Type material deposited at CC/ UFRN.

Description. Total length (head + trunk) of type series ranging between 0.57‒0.97 mm in adults. Habitus typical of the genus. Body totally unpigmented. Scales covering Ant. I‒II, ventral and dorsal head, dorsal trunk, lateral and ventral manubrium and dens. Legs and collophore without scales.

Head ( Figs 1‒6 ). Antennae shorter than body length, antennal ratio in type series as I: II: III: IV = 1: 1.72‒2.06: 1.09‒1.68: 2.96‒3.49. Ant. IV oval, without apical bulb and with at least three types of chaetae: blunt sensilla, bristle-like sensilla and ciliated chaetae ( Fig. 1 ). Ant. III sense organ with 2 rods, 3 surrounding guard sensilla plus some surrounding bristle-like sensilla and ciliated chaetae ( Fig. 2 ). Ventral post-labial chaetotaxy with about 19 ciliated chaetae of different lengths on latero-median field; cephalic groove with 2+2 surrounding anterior ciliated chaetae ( Fig. 3 ). Labial basolateral and basomedian fields with chaeta r absent , m1, e, l1‒2, a1–5 smooth ( Fig. 4 ). Labial palp with five smooth proximal chaetae ( Fig. 4 ). Labial palp papillae (and guard chaetae) formula as: H(2), A(0), B(5), C(0), D(4), E(4) + l.p.; lateral process finger-shaped, not reaching the papilla base ( Fig. 4 ). Outer maxillary lobe with basal and distal chaetae subequal and smooth; sublobal plate with one smooth appendage ( Fig. 4 ). Four prelabral smooth chaetae. Labral formula 4 (a1–2), 5 (m0–2), 5 (p0–2), all smooth chaetae ( Fig. 5 ). Eyes typically absent. Dorsal chaetotaxy with 4+4 mac and 1+1 mic on frontal series (f1–5, f4 as mic) plus 4 anterior (A0, A2–3, A5), 4 medio-ocellar (M1–4), 5 sutural (S2–5), 2 post-sutural (Ps2, Ps5), 3 postoccipital anterior (Pa2– 3, Pa5), 2 postoccipital medial (Pm1?, Pm3) and 4 postoccipital posterior (Pp1, Pp3–5) mic ( Fig. 6 ).

Thorax chaetotaxy ( Figs 7‒8 ). Central mac formula from Th. II to Abd. IV as 0,0/0,2,3,2. Mac mostly short in length. Antero-lateral edge of Th. II with a collar of weakly ciliated erect mac. Th. II with 1 ms, 1 anterolateral sens (al), 1 anterior (a2), 7 medial (m1–2, m4–7 plus one mic of uncertain homology) and 8 posterior (p1–6, p6e–6e2) chaetae ( Fig. 7 ). Th. III with 1 anterolateral sens (al), 3 anterior (a3?, a6–7), 4 medial (m6–7e) and 3 posterior (p2– 4) chaetae ( Fig. 8 ).

Abdomen chaetotaxy ( Figs 9‒13 ). Abd. I with 1 anterosubmedial sens (as), 1 anterior (a5), 6 medial (m2–6e) and no posterior chaetae; m2 can be displaced under the pseudopore ( Fig. 9 ). Abd. II with 1 anterosubmedial sens (as), 4‒5 anterior (a2– 2i, a5–7, a 2i present or absent), 6‒7 medial (m2– 3ei, m5–7, m3e present or absent) and 2 posterior (p6–7) chaetae ( Fig. 10 ). Abd. III with 1 ms, 1 anterosubmedial sens (as), 4‒5 anterior (a2– 2i, a5‒7, a 2i present or absent), 7‒8 medial (m2–3e2, m5, am6, pm6, m7, m3e2 present or absent) and 2 posterior (p6–7) chaetae, plus two unnamed lateral mes ( Fig. 11 ). Abd. IV with 1 posterior (ps), 1 anterosubmedial (as) plus at least 1 extra sens of uncertain homology close to E4; mac formula as 1 ‘B’ (B4), 1 ‘T’ (T7), 1 ‘De’ (De3), 3 ‘E’ (E3, E4p–4p2), 1 ‘Eel’ (Eel2), 1 ‘F’ (F3), and 2 ‘Fe’ (Fe3–4); central chaetae very similar to long sensilla, difficult to separate; 5 posterior chaetae, the lateral one smooth, plus two pseudopores ( Fig. 12 ). Abd. V with 1 anterosubmedial (as) plus 2 accessory sens (acc.p4–5), 1 lateral extra sens of uncertain homology, 5 anterior (a1, a3, a5–6e), 4 medial (m2–3, m5–5e), 2 posteroanterior (p5a, p6ai), and 8 posterior (p1, p3–5, p4p?, p5pi, ap6, pp6) chaetae ( Fig. 13 ).

Legs ( Figs 14‒15 ). Subcoxae I, II and III with 2 pseudopores each. Trochanteral organ with 4‒9 spine-like chaetae ( Fig. 14 ). Ungues with 3 inner teeth, 1 large pair at the base, both teeth equally sized, plus 1 unpaired distal smaller tooth; outer side without teeth. Unguiculi large, more than half the length of the claw, with a strong lamellate outer tooth. Tenent hair smooth, stout and capitate. Tibiotarsus III with a smooth inner distal chaeta, near the unguiculus ( Fig. 15 ).

Collophore ( Figs 16‒17 ). Anterior side with 2+2 long ciliated chaetae along ventral groove distal region ( Fig. 16 ). Posterior face with chaetae arranged as typical to the genus, with L1 and L2 smooth and subequal, M seen only by a large alveolus (chaetae lost in all the type series), 2+2 peg-like mic, and 1+1 long distal smooth chaetae (D). Lateral flaps with 2 smooth chaetae each ( Fig. 17 ).

Furcula ( Figs 18‒20 ). Manubrium without spines or spine-like chaetae. Dorsal side with lateral rows of ciliated chaetae, except by the more distal one, the sole smooth chaeta of dorsal manubrium ( Fig. 18 ). Manubrial plate with 2 pseudopores and 2 ciliated chaetae at each side ( Fig. 18 ). Ventral side covered by oval scales. Dens elongate, dorsal side with 2 rows of feathered scales, 5 internal (distal one larger than mucro) and outer row with 6 subequal scales; and 4 ciliated chaetae between the two rows ( Fig. 19 ). One outer smooth and 2 inner ciliated chaetae proximally, in a transversal row. Two slender smooth chaetae proximally in the inner ventral side, and 1 distally in the outer ventral side, close to mucro. Dens ventral side with oval scales ( Fig. 19 ). Mucro straight, elongate, bidentate apically ( Figs 19‒20 ).

Etymology. The name refers to the large inner paired basal teeth of unguis, that are equally sized in the new species. This structure has a remarkable unequal size in species similar to C. equidenticulati sp. nov.

Distribution and habitat. The new species was found in the transitional zone between Caatinga and Cerrado biomes, Piauí state, Northeast Brazil. According to the Köppen-Geiger system, the climate of the area is "Aw"— Tropical with a long dry season and rainy summer, characterized by high temperatures over all the year. The annual average temperature is 26.5ºC, the maximum temperature registered was 40.2ºC and the minimum was 14.6ºC. The annual average rainfall is over 1.250 mm, with 65% of this precipitation concentrated in three months (February, March and April) ( IBDF 1979). All specimens were collected from soil and leaf litter samples, in a typical savanna-like area populated by native grasses and sparsely distributed small trees and shrubs, some of them growing on accumulated soil in sandstone outcrops.

Remarks. Concerning the dorsal chaetotaxy interpretation of the new species, we considered the notes and drawings of Szeptycki (1979) for Cyphoderus . For example, on Th. II, ‘a’ series chaetae are difficult to identify on adults since most of them became part of the mesothorax collar and few could be lost during the development. Also chaetae m4 and m5 are quite similar in position to chaetae a5 and m4 of other Entomobryoidea, respectively. However, this resemblance could be interpreted as superficial since apparently chaeta a5 becomes progressively associated to the collar while the positions of m4 and m5 appear to be quite stable. We made such considerations since the overall Th. II chaetotaxy in Cyphoderus equidenticulati sp. nov. is almost identical to the presented by Szeptycki (1979, fig. 95), including the presence of one mic of uncertain homology between a2 and m4.

Following the classification criteria proposed by Delamare-Debouteville (1948) and the available dorsal chaetotaxy data, Cyphoderus equidenticulati sp. nov. resembles C. javanus Börner, 1906 from Java and C. songkhlaensis Jantarit, Satasook & Deharveng, 2014 from Thailand. The original description of C. javanus by Börner (1906) is very poorly detailed, therefore, we used the more detailed description of this species made by Yoshii (1980), to C. borneensis Yoshii, 1980 , posteriorly synonymized with C. javanus in Yoshii (1992) .

C. equidenticulati sp. nov. resembles C. javanus and C. songkhlaensis by 1 inner distal tooth on unguis; posterior face of ventral tube with 1+1 long smooth distal chaetae; and 4 ciliated chaetae between the two rows of feathered scales of dens. C. equidenticulati sp. nov. resembles only C. songkhlaensis by anterior face of collophore with 2+2 ciliated chaetae (smooth in C. javanus ); and by identical organization of manubrial plate pseudopores and chaetae (data lacking for C. javanus ). The new species differs by: 1) basomedian field of head with chaeta l2 well developed (vestigial in C. javanus and C. songkhlaensis , present as a minute and thick mic); 2) claw without an outer tooth on unguis (1 basal outer tooth in C. songkhlaensis ); 3) claw with 1 pair of equally developed inner basal teeth (in C. javanus and C. songkhlaensis the paired teeth are remarkable unequal); 4) posterior face of collophore with L1 and L2 smooth (ciliated in C. javanus and C. songkhlaensis , M lacking in the new species); 5) mucro bidentate, without a minute external tooth (third minute external tooth present in C. javanus and C. songkhlaensis ); and 6) trochanteral organ with 4‒9 spine-like chaetae (approximately 18 in C. javanus and 11‒22 in C. songkhlaensis ). The information about C. javanus in literature is limited, but the detailed description made by Jantarit et al. (2014) to C. songkhlaensis allows us to point out further differences between the two species: 1) dorsal head without chaetae M0 (present in C. songkhlaensis ); 2) ventral head with 2+2 strongly ciliated chaetae along the ventral groove (4+4 smooth or finely serrated in C. songkhlaensis ); 3) m6 and m6e present as mac in Abd. I (m6 as mic and m6e lacking in C. songkhlaensis ); 4) m7 and p7 as mac in Abd. II (m7 as mic and p7 lacking in C. songkhlaensis ); 5) two slender chaetae proximally located in the inner ventral side of dens, and 1 distally located in the outer ventral side, all smooth (in C. songkhlaensis , all are ciliated).

Figures

FIGURE 6. Cyphoderus equidenticulati sp. nov.: dorsal head chaetotaxy.

FIGURES 1–5. Cyphoderus equidenticulati sp. nov.: 1, apex of Ant. IV; 2, Ant. III sense organ and surrounding chaetae; 3, post-labial ventral chaetotaxy; 4, Labium with labial palp, proximal chaetae, outer maxillary lobe and basolateral and basomedian fields chaetotaxy; 5, labral chaetae.

FIGURES 7–11. Cyphoderus equidenticulati sp. nov.: dorsal chaetotaxy; 7, Th. II; 8, Th. III; 9, Abd. I; 10, Abd. II; 11, Abd. III.

FIGURES 12–13. Cyphoderus equidenticulati sp. nov.: dorsal chaetotaxy; 12, Abd. IV; 13, Abd. V.

FIGURES 14–20. Cyphoderus equidenticulati sp. nov.: 14, trochanteral organ; 15, empodial complex III and distal tibiotarsus; 16, collophore anterior side; 17, collophore posterior side and lateral flaps; 18, distal manubrium and manubrial plate; 19, dens and mucro, inner dorsal view; 20, detailed view of mucro.