Dicranocentrus melinus, Xisto, Thiago & Mendonça, Maria Cleide De, 2016

Xisto, Thiago & Mendonça, Maria Cleide De, 2016, Two new species of Dicranocentrus Schött, 1893 (Collembola: Entomobryidae) from Serra do Gandarela, Minas Gerais State, Brazil, Zootaxa 4079 (2), pp. 217-228 : 218-219

Dicranocentrus melinus sp. nov.

Figs 1–17

Type locality. “Parque Nacional da Serra do Gandarela”, Caeté municipality, Minas Gerais State, Rain forest litter, lat/long coordinates 20°1'49.91" S; 43°40'43.83" W, about 1500 meters a.s.l.

Type material. Holotype: male, slide 2276a CM/ MNRJ, 29–02/XII/2011, Abrantes E.A. & Silveira T.C. leg. Paratypes: slides 2273a CM/ MNRJ, 2273b CM/ MNRJ, 2273c CM/ MNRJ, 2273d CM/ MNRJ and 2273e CM/ MNRJ, 29-02/XII/2011, Abrantes E.A. & Silveira T.C. leg.; slide 2277 CM/ MNRJ, 29–02/XII/2011, Abrantes E.A. & Silveira T.C. leg.; slide 2279 CM/ MNRJ, 29–02/XII/2011, Abrantes E.A. & Silveira T.C. leg.; slide 2281 CM/ MNRJ, 29–02/XII/2011, Abrantes E.A. & Silveira T.C. leg.; slides 2285a CM/ MNRJ and 2285b CM/ MNRJ, 29– 02/XII/2011, Abrantes E.A. & Silveira T.C. leg.; slide 2289 CM/ MNRJ, 29–02/XII/2011, Abrantes E.A. & Silveira T.C. leg.; slide 2293 CM/ MNRJ, 29–02/XII/2011, Abrantes E.A. & Silveira T.C. leg.

Description. Body length: 3.5 mm to 4.0 mm. Habitus elongated typical of genus. General color strongly yellowish with brownish scales. Antennae and legs with dark bluish pigmentation ( Fig. 1 ).

Head. Antennae long, approximately three to four times the length of cephalic diagonal. Ratio of antennal segments I:II:III:IV:V:VI = 1.0:3.1:1.5: 3.8:11.8:4.7 ( Fig. 2 ). Ant. I–IV with ciliated microchaetae interspersed with smooth chaetae and small scales. Ant. V with sensory organ located in the distal dorsolateral region, composed of two robust rod-like sensilla, individually covered by a tegument fold and protected laterally by guard sensilla and ciliated chaetae ( Fig. 3 ). Ant. VI with one subapical pin seta ventrally; apical bulb absent ( Fig. 4 ). Ant.

V and VI annulated, with ciliated microchaetae interspersed with smooth chaetae arranged in rings on finely granulated tegument and without scales. Eyes 8+ 8 in strongly pigmented eye patch, G and H eyes smaller than others ( Fig. 5 ). Pre-labral chaetae simple; labral chaetotaxy 4/5,5,4, all chaetae smooth; labral papilla of type II ( Fig. 6 ). Maxillary palp simple with basal chaeta subequal to apical chaeta, and 4 sublobal hairs ( Fig. 7 ). Outer labial papilla with a small lateral process reaching half of papilla E; 5 guard chaetae present (e1, e3, e4, e5 and e6) ( Fig. 8 ). Labial triangle with chaetae M1 and M2 ciliated, chaeta r smooth and smaller than chaeta E ( Fig. 9 ).

Appendages. Trochanteral organ consisting of approximately 65 small spines and subequal smooth chaetae; approximately 50 ciliated mesochaetae laterally and few small scales; trochanteral chaeta longer than trochanter ( Fig. 10 ). Tibiotarsi covered with numerous ciliated chaetae and small scales; one row of spiny ciliated chaetae and one smooth chaeta on inner margin. Unguis long and robust with a pair of basal teeth and a distal unpaired tooth on inner margin, two lateral and one dorsal basal teeth; unguiculi lanceolate with a median inner tooth; tibiotarsal tenent hair elongate and capitate ( Fig. 11 ). Ventral tube covered with 20+20 subequal ciliated mesochaetae and 3+3 ciliated macrochaetae anteriorly; ciliated chaetae of various sizes interspersed with scales posteriorly; approximately 40 smooth and ciliated mesochaetae laterally ( Fig. 12 ). Tenaculum well developed, with 4+4 teeth and one ciliated macrochaeta in basomedian region ( Fig. 13 ). Dens long, crenulate, with about 55 spines only in the inner basal area ( Fig. 14 ); distal part of dens smooth and measuring about twice mucro’s length. Mucro small with two teeth and one basal spine ( Fig. 15 ).

Macrochaetotaxy. Head with 13+13 chaetae on antennal group (An); anterior group with 4+4 chaetae (A2, A3, A4 and A5) and unpaired chaeta A0; median-ocellar line with 3+3 chaetae (M1, M2 and M3); sutural group with 6+6 chaetae (S1, S3, S4, S5, S6 and S7) and unpaired chaeta S0; post sutural chaeta (Ps) absent; post ocellar chaeta (Po) present; posterior group (P) with 4+4 chaetae ( Fig. 16 ). Th. II with 2+2 inner Mc., 4+4 outer Mc. in median region and 6+6 posterior Mc.; Th. III with 9+9 Mc.; Abd. I with 5+5 Mc.; Abd. II with 2+2 inner and 1+1 outer Mc.; Abd. III with 2+2 inner and 2+2 outer Mc.; Abd. IV with 5+5 inner Mc. ( Fig. 17 ).

Discussion. The species Dicranocentrus melinus sp. nov. belongs to gracilis -group sensu Mari Mutt, 1979 together with D. schoetti Mari Mutt, 1979 and D. heloisae Arlé & Mendonça, 1982 due to the absence of chaeta A1, S2, Ps and up to 6+6 chaetae P on dorsal head.

The new species is similar to D. schoetti Mari Mutt, 1979 , described from Peru, by the presence of pin seta, G and H eyes reduced, guard chaetae e1, e3, e4, e5 and e6 on outer labial papilla, smooth chaetae on metathoracic tibiotarsi, capitate tenent hair, absence of spines on outer basal region of dens, and 4+4 P chaetae dorsally on head. However, D. melinus sp. nov. shows labral papilla type II according the classification preconized by Mari Mutt (1981), maxillary palp with basal chaeta subequal to apical chaeta, ciliated chaetae on labial triangle, unguis with three teeth on inner margin, 12+12 Mc. on Th. II, 3+3 Mc. on Abd. II and 5+5 Mc. on Abd. IV. According Mari Mutt (1979), D. schoetti exhibits labral papilla type III, maxillary palp with basal chaeta longer than apical chaeta, labial triangle without ciliated chaetae, unguis with four teeth on inner margin, 11+11 Mc. on Th. II, 2+2 Mc. on Abd. II and 6+6 inner Mc. on Abd. IV.

D. melinus sp. nov. is also similar to D. heloisae Arlé & Mendonça, 1982 , described from Brazil, by the presence of pin seta, absence of apical bulb, G and H eyes reduced, maxillary palp with basal chaeta subequal to apical chaeta, guard chaetae E1, E3, E4, E5 and E6 on outer labial papilla, presence of smooth chaetae on metathoracic tibiotarsi, capitate tenent hair, tenaculum with ciliated chaeta and presence of spines on outer basal region of dens. However, D. melinus sp. nov. can be distinguished by labral papilla of type II, four sublobal hairs, labial triangle with chaetae M1 and M2 ciliated, approximately 65 spines on trochanteral organ, unguis with three teeth on inner margin, absence of spines on outer basal region of dens, 4+4 Mc. P on dorsal head and 12+12 Mc. on Th. II. D. heloisae , on the other hand, shows labral papilla of type III, three sublobal hairs, labial triangle with chaeta M1 ciliated, approximately 100 spines on trochanteral organ, unguis with four teeth on inner margin, spines on outer basal region of dens, 1+1 Mc. P dorsally on head and 13+13 Mc. on Th. II ( Arlé & Mendonça 1982; Xisto & Mendonça 2014).

Etymology. The name melinus , derived from the Greek word meli that means honey, in a reference to the coloration displayed by the new species.

Figures

FIGURE 1. Dicranocentrus melinus sp. nov.: Habitus in ethanol.

FIGURES 2 – 9. Dicranocentrus melinus sp. nov.: 2, antenna—chaetae omitted; 3, sensory organ on Ant. V; 4, ventral view of Ant. VI apex; 5, eyepatch; 6, labrum; 7, maxillary palp and sublobal plate; 8, outer labial papilla with guard chaetae (L. P. — lateral process); 9, labial triangle.

FIGURES 10 – 13. Dicranocentrus melinus sp. nov.: 10, trochanteral organ; 11, distal part of metathoracic tibiotarsus and foot complex with capitate tenent hair; 12, anterior side of ventral tube; 13, tenaculum.

FIGURES 14 – 17. Dicranocentrus melinus sp. nov.: 14, spines on basal region of dens; 15, distal region of dens and mucro; 16, dorsal cephalic macrochaetotaxy (An—antennal group, A—anterior group, M—median-ocellar line, S—sutural group, Po—post ocellar chaeta, P—posterior group); 17, half dorsal macrochaetotaxy, bothriotricha and pseudopores of Th. II to Abd. IV.