Arrhopalites glabrofasciatus, Zeppelini & Brito & Lima, 2018

Zeppelini, Douglas, Brito, Roniere A. & Lima, Estevam C. A., 2018, Three new species of Collembola (Arthropoda: Hexapoda) from Central Brazilian shallow caves: side effects of long term application of environmental law on conservation, Zootaxa 4500 (1), pp. 59-81 : 60-69

Arrhopalites glabrofasciatus sp. nov.

Figs 1–16 , Table 1

Type material. Holotype adult female on slide, Brazil, Minas Gerais, Brumadinho (43°57’51”W; 20°09’03”S), PBR 41, Iron Cave , 08.II.2017, leg. Carste Team. Holotype deposited at CRFS-UEPB # 10375 .

Paratype adult, female, Brazil, Minas Gerais, Brumadinho (43°57’51”W; 20°09’03”S), PBR 41, Iron cave , 08.II.2017, leg. Carste team, CRFS-UEPB # 10379 .

Paratype adult female, Brazil, Minas Gerais, Brumadinho (43°57’51”W; 20°09’03”S), PBR 41, Iron cave , 08.II.2017, leg. Carste team, CRFS-UEPB # 10380 .

Paratype adult female, Brazil, Minas Gerais, Brumadinho (43°57’51”W; 20°09’03”S), PBR 41, Iron cave , 08.II.2017, leg. Carste team, CRFS-UEPB # 10381 .

Paratype adult female, Brazil, Minas Gerais, Brumadinho (43°57’51”W; 20°09’03”S), PBR 41, Iron cave , 08.II.2017, leg. Carste team, CRFS-UEPB # 10383 .

Additional material (deposited in CRFS-UEPB):

Brazil, Minas Gerais, Matozinhos (44°05’55”W; 19°32’12”S), BM 157 , limestone cave, 07-20.XII.2016, leg. Spelayon team. CRFS-UEPB # 10376 .

Brazil, Minas Gerais, Matozinhos (44°05’38”W; 19°31’44”S), BM 105 , limestone cave, 07-20.XII.2016, leg. Spelayon team. CRFS-UEPB # 10377 .

Brazil, Minas Gerais, Rio Acima, Serra do Gandarela (43°39’52”W; 20°02’51”), GAND 122 , limestone cave, 14.VII–18.IX.2016, leg. Carste team. CRFS-UEPB # 10378 .

Brazil, Minas Gerais, Rio Acima, Serra do Gandarela (43°39’40”W; 20°04’37”), GAND 027 , limestone cave, 14.VII–18.IX.2016, leg. Carste team, CRFS-UEPB # 10382 .

Brazil, Minas Gerais, Rio Acima, Serra do Gandarela (43°40’09”W; 20°03’59”), GAND 110 , limestone cave, 14.VII–18.IX.2016, leg. Carste team, CRFS-UEPB # 10384 .

Description. Habitus sminthuroid ( Fig. 1 ). Holotype female total length (head+body) 1116.95µm, cephalic diagonal 345.22 µm, other measures as in Table 1. Color. Body pale yellow or white.

Ant I with 5 normal chaetae on anterior side, with one small microchaeta in apical part on posterior side. Ant II with 7 apical chaetae, 3 medial and 4 basal, one basal internal much longer (~3×) than other three ( Fig. 2 ). Ant III apical organ with 2 sensilla inserted in a single pit, Ape and Ai short and bristlelike, Aai minute, rodlike and blunt, other chaetae normal. Ant III mid-dorsal part with 4 chaetae longer (~2×) than other in the segment ( Fig. 3 ). Ant IV 6 (exceptionally 5) subdivided, the subsegmentation is annulated and forms a ring between subsegments, the basal one with 4 whorl of chaetae and an apical sensillum (5,9,8,8–1 respectively from the base), the three intermediary subsegments bearing 8–2,7–3,8–4 and the apical subsegment with 35–6, subapical organite at the base of a strongly curved chaeta ( Fig. 4 ).

Eyes absent. Posterior cephalic chaetae slightly spinelike ( Figs 5–7 ), posterior dorsal chaetotaxy A,B,C,D as 5,3,5,4, interantennal region with 4α and 3β chaetae ( Fig. 5 ), cuticle shows two smooth areas in from of the antennae ( Fig. 6 ); frontal head chaetotaxy a,b,c,d,e,f with 8,9,13,14,13,14 chaetae ( Fig. 6 ). Labral chaetotaxy according to formula a,m,p,pl with 4,5,5,6 chaetae respectively ( Fig. 7 ).

Leg I ( Fig. 8 ): precoxae and coxa with 1 chaeta each; trochanter with 4 chaetae; femur with 11 chaetae; tibiotarsus with 43 chaetae, Ja slightly curved, whorls I–V with 8 chaetae, and region F with 3 primary FP chaetae (e, ae, pe), secondary chaetae FSa absent; unguis with a weak tunica and 1 inner tooth; unguiculus subapical filament exceeding the tip of the unguis, with a clear corner tooth.

Leg II ( Fig. 9 ): epicoxae and precoxae with 1 chaeta each, coxa with 2 primary chaetae, 1 microsensillum and 1 secondary chaetae i2; trochanter with 5 chaetae, being 3 anterior, a trochanteral organ (a1) and 1 posterior; femur with 10 chaetae and 1 basal curved bristlelike chaeta; tibiotarsus with 43 chaetae: whorl I with 9 chaetae, Ja strait, whorls II–IV with 8 chaetae each, whorl V with 7 chaetae, and region F with 3 primary FP chaetae (e, ae, pe), secondary chaeta FSa absent; unguis with tunica and 1 small inner tooth; unguiculus subapical filament exceeding the tip of the unguis, a small corner tooth present.

Leg III ( Fig. 10 ): epicoxae and precoxae with 1 distal chaeta each, coxa chaetotaxy as in leg II; trochanter with 3 anterior chaetae, a metatrochanteral organ, and 1 posterior chaeta; femur with 12 chaetae and 2 short chaetae (p2 and pi4) on posterior face; tibiotarsus with 43 chaetae: whorl I with 9 chaetae, Ja normal, whorls II–IV with 8 chaetae, whorls V with 7 chaetae, and region F with 3 primary FP chaetae (e, ae, pe), secondary chaetae FSa present; unguis with a clear tunica and 1 small inner tooth; unguiculus subapical filament short or absent, never reaching the tip of the unguis, corner tooth present.

Ventral tube with 1+1 apical anterior chaetae. Ramus of tenaculum tridentate, with basal finger like appendix, corpus with 2 apical chaetae.

Furca: Manubrium with 4+4 distal chaetae, p2–p3 absence; dens anterior chaetotaxy Ia–Iia–IIIa–Iva–Ba as 3– 2–2–1–1, Ia slightly spinelike; posterior chaetotaxy Ie, I–IIIpe, Ip slightly spinelike, Ii and III-IVpi strongly spinelike ( Fig. 11 ). Mucro gutterlike, both lamellae serrated, constricted at the distal third, with spoon shaped tip ( Figs 12 and 13 ).

Great abdomen. All chaetae smooth and acuminated; thorax and Abd I chaetae short, dorsal posterior abdominal chaetae long and slender; chaetotaxy as in Fig. 14 ; trichobothria A/B/C equidistant, forming an obtuse angle of 163° opening forward ( Figs 14 and 15 ).

Small abdomen of female: one small axial and 2+2 strong lateral cuticular spines on the upper valve, the lower valves present 2+2 strong spines and a very small spine at the base of the inner one, which may be missing in some specimens ( Fig. 16 ) trichobothrium D present, chaetae mps1–3 and mpi1–2 and mpi4 broad and winged; subanal appendage flattened, gutterlike and apically serrated.

Etymology. The name of the new species refers to the smooth areas in front of the antennae (from Latin glabrus = smooth; fascia = bands, stripes).

Distribution and habitat. Good’s Biogeographic zone 27 ( Good 1974; Culik & Zeppelini 2003). The climate according to Köppen’s system is ‘as’ ( Köppen 1936; Shear 1966), presenting dry winters and wet summers, average temperatures of 18 °C during winter and 22 °C in summer. Populations of new species were found in several caves both in iron and limestone rock, where they were found on deposits of organic debris. Some of the caves, mainly those on iron rock matrix are rather too small to present a clear zonation from the entrance to the bottom of the caves, the inside temperatures and humidity vary mostly with the external conditions, even though the humidity is always higher inside the caves. The surrounding vegetation is dominated by semi-deciduous forest and dry woods. Some of the caves are next to the mining degraded areas and suffers intense direct and indirect environmental pressures from this activity.

Remarks. The new species can be diagnosed by a combination of characters, but the most striking feature is the angle of the trichobothrial complex, A. glabrofasciatus sp. nov. presents trichobothria ABC equidistant forming an angle of 163° opening forward. This thrichobothrial pattern is observed in Pygmarrhopalites Vargovitsh, 2009 (discussed below) and Troglopalites Vargovitsh, 2012 .

The new species is the only known Brazilian species which lacks eyes, it can be differentiated from A. amorimi Palacios-Vargas & Zeppelini, 1996 and A. heteroculatus Zeppelini, 2006 , both with 2+2 eyes and long apical filament of unguiculus III, A. amorimi has the Ant IV divided into four ringed subsegments, and A. heteroculatus lacks tunica in the first unguis. Other Brazilian species present 1+1 eyes, A. gnaspinii Palacios-Vargas & Zeppelini, 1996 and A. lawrencei Palacios-Vargas & Zeppelini, 1996 have the Ant IV divided into six ringed subsegments, lack tunica ( A. lawrencei lacks tunica in all unguis) and inner tooth in the first unguis, A. gnaspinii presents the Aai of the AIIIO blunt and larger than the organ sensilla, similar to Ape in length. Arrhopalites lawrencei presents a long apical filament in the unguiculus III, exceeding the tip of unguis, as well as A. alambariensis , which has an undivided Ant. IV, and A. botuveraensis Zeppelini, 2006 , which presents Ant. IV with five ringed subsegments and lacks tunica on unguis I.

According to Vargovitsh (2009), species of the genus Arrhopalites present the trichobothria ABC forming an angle close to 90° with B closer to C than to A, AB and BC equidistant, p chaetae of Abd I located above of the trichobothrium B and chaetae c1 above of the trichobothrium C. While those of the genus Pygmarrhopalites Vargovitsh, 2009 present an obtuse angle, close to 180° with AB<BC or AB and BC equidistant, p chaetae of Abd I located below of the trichobothrium B and chaetae c1 lies at or below of the trichobothrium C (this last characteristic is also observed in A. macronyx Vargovitsh, 2012 ). This finding suggests that Pygmarrhopalites may be paraphyletic in relation to Arrhopalites . The genus Pygmarrhopalites is mainly based on the thrichobothrial pattern and the presence of FS chaeta on all Tita, both characters supposed to be plesiomorphic ( Zeppelini 2011). The trichobothrial pattern (angle and relative ABC distance) is highly variable even among subgroups of Pygmarrhopalites ( Vargovitsh 2009) , a putative apormorphy for Pygmarrhopalites would be the reduction of the anterior chaetae on dens (usually 3,2,1,1) which is plesiomorphic in Arrhopalites (usually with five rows of anterior chaetae), even though this character is subject to homoplasy (e.g. A. nivalis Yosii, 1966 with 3,2,1,1). The genus Arrhopalites , at the other hand, must be monophyletic, supported by a number of synapomorphies (e.g. cuticular spines on the anal valve, absence of FSa on tita I and II). A more accurate definition on the phylogenetic relationships in Arrhopalitidae demands a detailed revision of the whole chaetotaxy of species of each subgroup.

Figures

FIGURE 1. Arrhopalites glabrofasciatus sp. nov.: habitus of female mounted in slide.

FIGURES 2–4. Arrhopalites glabrofasciatus sp. nov.: 2, chaetotaxy of antennal segments I and II; 3, chaetotaxy of antennal segment III; 4, chaetotaxy of antennal segment IV, with apical bulb at the base of a hooklike chaeta.

FIGURES 5–7. Arrhopalites glabrofasciatus sp. nov.: 5, dorsal head chaetotaxy; 6, frontal head chaetotaxy; 7, clypeo-labral chaetotaxy.

FIGURES 8–10. Arrhopalites glabrofasciatus sp. nov.: 8, chaetotaxy of foreleg; 9, chaetotaxy of mid leg; 10, chaetotaxy of hind leg.

FIGURES 11–12. Arrhopalites glabrofasciatus sp. nov.: 11, chaetotaxy of manubrium and dens; 12, mucro.

FIGURE 13. Arrhopalites glabrofasciatus sp. nov.: view of Abd VI and furca/

FIGURE 14. Arrhopalites glabrofasciatus sp. nov.: chaetotaxy of great abdomen.

FIGURE 15. Arrhopalites glabrofasciatus sp. nov.: fragment of abdomen with trichobothrial complex.

FIGURE 16. Arrhopalites glabrofasciatus sp. nov.: chaetotaxy of female Abd VI.