A new genus and a new species of Sminthuridae (Collembola: Symphypleona) from Atlantic Forest of Brazil
Author
Silva, Diego Dias Da
Author
Palacios-Vargas, José G.
Author
Bellini, Bruno Cavalcante
text
Zootaxa
2015
3990
3
410
418
journal article
39791
10.11646/zootaxa.3990.3.5
8f515769-86ed-4d37-912a-68596c78dcfd
1175-5326
241037
4C50D617-1D1F-498C-8E69-904683254448
Varelasminthurus
gen. nov.
Diagnosis.
Head and body presenting only smooth and thin sharp chaetae; 8+8 subequal eyes lenses (
Figs 1C
and
2
); head frontal area with row C with 2+2 chaetae (
Fig. 2
); tibiotarsi bearing only normal chaetae and 1 oval organ each (
Figs 5–8
); pretarsal chaeta present only anteriorly (
Figs 9–11
); unguis with tunica and cuticular granulation, one anterior external deep cavity, one posterior external crest with 6 teeth and with finely serrated inner edge (
Figs 1F
and
9–11
); unguiculi shorter than unguis, with external cavity and microserrations; tenent hairs absent (
Figs 9– 11
); rami of tenaculum bidentate, with basal appendix (
Fig. 1G
); trochanter III with 2 trochanteral organs (
Fig. 1D
) and 1 posterior spine; anterior dental chaetae formula 3, 2, 1…1 (
Fig. 12
); mucronal edges almost smooth, with proximal heel-like structure developed and striated (
Fig. 1H
); trichobothrium B short, trichobothria C and D longer than A (
Fig. 14
); female with some thicker circumanal chaetae, subanal appendage smooth and elbowed (
Fig. 15
).
Type
species.
Varelasminthurus potiguarus
gen. nov.
sp. nov.
Etymology.
The genus is named after deceased Prof. Adalberto Antônio Varela Freire, for his important contributions to the University of Rio Grande do Norte,
Brazil
.
Remarks.
The interpretation of Betsch (1980) and
Richards (1968)
were considered for the tenaculum rami, which recognizes the basal tooth as coming from the basal appendix present in other groups of Symphypleona. In the other hand, the analysis of
Bretfeld (1999)
suggests tridentate tenaculum as a synapomorphy for Sminthuroidea, which also fits the morphology seen in
Varelasminthurus
gen. nov.
with rami bidentate and basal appendix projected laterally.
The new genus clearly belongs to the family
Sminthuridae
due to the position of thricobothria A, B and C; Ant. IV longer than Ant. III and elbowed between these two segments; 8+8 eye lenses; and the presence of a long ventral tube (
Bretfeld 1999
). However, it presents a set of morphological features which obscure its position within one of the two subfamilies of this family,
sensu
Betsch (1980). It differs from most other
Sminthuridae
by the presence of only one pretarsal chaeta (instead of two) and smooth mucronal edges (instead of serrated). Indeed, the study under SEM revealed there is a kind of vestigial serrated area in inner edge of mucro (
Fig. 1G
), which may have been derived from the original serrated condition of other
Sminthuridae
.
Even though the particular morphology of
Varelasminthurus
gen. nov.
, here we consider this new genus within
Sminthurinae
sensu stricto
because its antennae are relatively long, the Ant. IV has well defined subsegments, there is no neosminthuroid chaetae, it has a long anterior dental formula, and mucro is not sharp or notched. Also, all other
Sminthuridae
genera presenting unguis with cavity belong to this subfamily.
Due to unguis morphology,
Varelasminthurus
gen. nov.
is probably close related to other four genera of
Sminthurinae
(
Gisinurus
,
Songhaica
,
Dietersminthurus
and
Soqotrasminthurus
), but can be readily separated from them by the lack of posterior pretarsal chaetae. Also, the following combination of characters is only seen in the new genus: 1+1 tenaculum chaetae; only 7 anterior dental chaetae; smooth mucronal edges; and absence of neosminthuroid chaetae (a detailed comparison among cited genera provided in
Table 1
). Finally, another important diagnostic feature of
Varelasminthurus
gen. nov.
is the peculiar chaetotaxy of line C on cephalic frontal area, with 2+2 chaetae and without axial substitution, a disposition of chaetae not seen in any other genera of the family (
Betsch & Waller 1994
).
TABLE 1.
Comparison of cited genera of
Sminthuridae
. (+) present; (-) absent.
Genera Eye Tenacular number chaetae |
Posterior pretarsal chaetae |
Dental anterior chaetae number |
Mucro edges |
Neosminthuroi d chaetae |
Dietersminthurus
5+5 1+1
|
+ |
8 |
serrate |
- |
Gisinurus
8+8 1+1
|
+ |
13 |
serrate |
- |
Songhaica
8+8 1+1
|
+ |
5 |
smooth |
+ |
Soqotrasminthurus
8+8 2+2
|
+ |
12 |
smooth |
- |
Varelasminthurus
gen. nov.
8+8 1+1
|
- |
7 |
smooth |
- |
Varelasminthurus potiguarus
gen. nov.
sp. nov.
Figs 1–16
|
Type
material.
Holotype
: female on slide,
Brazil
, Rio Grande do Norte State, Tibau do Sul, Parque Estadual
Mata
de Pipa, pitfall traps,
8.ii.2013
. Silva, D. coll.
Paratypes
: 1 allotype and other male on same slide as
holotype
;
7 females
in different slides, same data as
holotype
.
Type
material deposited at
Collembola
Collection of
DBEZ
/
UFRN
, number 1002.
Description.
Habitus sminthuroid (
Figs 1A–B
).
Holotype
female total length (head+body)
0.82 mm
; body
0.71 mm
; longitudinal head
0.31 mm
; antenna
0.64 mm
; furca
0.46 mm
. Allotype male total length (head+body)
0.64 mm
; body
0.53 mm
; longitudinal head
0.23 mm
; antenna
0.57 mm
, furca
0.37 mm
.
Color in alcohol. Body pale yellow with light blue pigment covering clypeal region of head, antennae and distal legs, and dark pigment covering eye patches; dorsal surface of body with a characteristic pattern of black and brown spots (
Figs 1A–B
).
Head. 8+8 eyes, eye patches with one interocular acuminated chaeta (
Fig. 2
); labral chaetotaxy: a: 4; m: 5; p:5; pl:4; clypeal, interantennal and frontal area of head with acuminate chaetae, arranged as in
Fig. 2
; mandibles and maxillae subequal in size.
Antennae (
Fig. 3
).
Holotype
(female) antennal segmentation ratio: 1: 1.42; 4.01; 9.53, allotype (male): 1: 1.51; 5.21; 8.53. Ant. I with 5 chaetae; Ant. II with 16 chaetae; Ant. III with 37-40 chaetae, apical organ with 2 sense rods within invagination, Aai as a microsensillum (
Fig. 4
); Ant IV with 11 subsegments; without apical bulb.
Leg I (
Fig. 5
). Coxa with 1 chaeta; trochanter with 2 chaetae in proximal and
2 in
medial position; femur with 15 chaetae; tibiotarsus with smooth and acuminated chaetae; primary chaetae missing: Iai, IIai, Iae, Ip, secondary chaetae present: 3ai, 4ai1, Vai, FSai, 3a, 4a1, FSa, 2ae, 3ae, 4ae1, FSe↑, FSpe↓, 3p, 4p1, 3pi, 4pi1, Vpi, FSpi, oval organ
O
4pe present (
Fig. 6
); anterior pretarsal chaeta present; unguis with tunica and cuticular granulation, one anterior external deep cavity, one posterior external crest with 6 teeth, finely serrated (with 10–13 teeth) in inner side (
Fig. 9
); unguiculus shorter than unguis, with one external cavity and finely serrated (with 4–5 teeth); ratio unguis: unguiculus 1: 0.7.
Leg II (
Fig. 7
). Coxa with 2 chaetae; trochanter with 2 chaetae in proximal,
2 in
medial and
1 in
distal position; femur with 15 chaetae; tibiotarsus with smooth and acuminated chaetae, primary chaetae missing: Iai, IIai, Iae, Ip, Vp, secondary chaeta present: 3ai, 4ai1, Vai, FSai, 3a, 4a1, FSa, 2ae, 3ae, 4ae1, FSe↑, FSpe↓, 3p, 4p1, 3pi, 4pi1, Vpi, FSpi, oval organ
O
4pe present; anterior pretarsal chaeta present; unguis and unguiculus with similar morphology seen in leg I (
Fig. 10
); ratio unguis: unguiculus 1: 0.7.
Leg III (
Fig. 8
). Coxa with 4 chaetae; trochanter with 5 chaetae, 2 trochanteral organs (
Fig. 1D
) and one thick acuminated spine on posterior side (
Fig. 8
); femur with 16 chaetae; tibiotarsus with smooth and acuminated chaetae, primary chaetae missing: Iai, IIai, Iae, Ip, Vp, IIpi, secondary chaetae present: 3ai, 4ai1, 4ai2, Vai, FSai, 2a, 3a, 4a1, FSa, 2ae, 3ae, 4ae1, FSe↑, FSpe↓, 2p, 3p, 4p1, 3pi, 4pi1, Vpi, FSpi,
3i
,
4i
1, oval organ
O
4pe present; anterior pretarsal chaeta present (
Fig. 1E
); unguis and unguiculus with similar morphology seen in leg I (
Fig. 1E–F
and
11
); ratio unguis: unguiculus 1: 0.7.
FIGURE 1A–H
.
Varelasminthurus potiguarus
gen. nov.
sp. nov.
:
A
, dorsal view of specimen in 70% ethanol;
B
, lateral view of habitus of specimen in 70% ethanol; SEM Images of:
C
, frontal view of head;
D
, trochanter of leg III (arrows point to oval organs);
E
, anterior view of hind empodial complex (arrow points to pretarsal chaeta);
F
, posterior view of hind empodial complex (arrow points to posterior external crest);
G
, posterior view of tenaculum;
H
, inner view of dent apex and mucro.
FIGURES 2–4
.
Varelasminthurus potiguarus
gen. nov.
sp. nov.
:
2
, cephalic cheatotaxy (circles points extra chaetae, out of lines);
3
, left antenna;
4
, apex of Ant. III.
Ventral tube with smooth sacs, lateral papillae and two pairs of chaetae (
Fig. 13
). Each ramus of tenaculum bidentate, with basal appendix; corpus with 2 apical chaetae (
Fig. 1G
). Furca: manubrium dorsally with 6+6 posterior chaetae; dorsal dens chaetotaxy as shown in
Figure 12
; anterior dental chaetae formula 3, 2, 1…1, chaetae Vpi and VIpi thicker than others; mucro spatulate; mucronal edges smooth, with proximal heel-like structure developed and striated (
Fig. 1H
); ratio mucro: dens: manubrium 1: 2.4; 1.9.
Great abdomen. Dorsal chaetae smooth and acuminate; thorax without any visible segmentation; thoracic chaetotaxy as in
Figure 14
; trichobothria A/B/C in inverted pattern
sensu
Richards (1968)
, almost in line (
Fig. 14
); trichobothria B shorter than C.
FIGURES 5–11
.
Varelasminthurus potiguarus
gen. nov.
sp. nov.: 5
, leg I;
6
, oval organ of leg I;
7
, leg II;
8,
leg III;
9
, empodial complex of leg I;
10
, empodial complex of leg II;
11
, empodial complex of leg III.
FIGURES 12–16
.
Varelasminthurus potiguarus
gen. nov.
sp. nov.
:
12
, chaetotaxy of furca and mucro shape;
13
, lateral view of ventral tube;
14
, anterior region of great abdomen and thoracic chaetotaxy;
15
, female small abdomen chaetotaxy (lateral view);
16
, male small abdomen (lateral view).
Small abdomen. Female chaetotaxy as shown in
Figure 15
; trichobothria D present and very long; 2+2 oval organs present; chaetae ms1, ms3, mps1, mps3, mpi1 and mpi2 slightly thicker than others; subanal appendage smooth, acuminated and apically turned toward anal opening; male chaetotaxy and genital opening as in
Figure 16
.
Etymology.
“Potiguar” refers to the native indigenes from the
type
locality, Rio Grande do Norte State,
Brazil
.
Distribution and Habitat.
The specimens were collected during the dry season from leaf litter in two Atlantic Forest remnants, at coordinates:
S 06°22'10"
W 35°00'28"
and
S 06°14'56.11"
W 35°3'29.01"
, from Rio Grande do Norte State, Northeastern Region of
Brazil
; Good’s biogeographic zone 27 (
Good 1974
).
Remarks.
Specimens of
Varelasminthurus potiguarus
gen. nov.
sp. nov.
run in
Gisinurus
Dallai, 1970
, following the key to genera proposed by
Bretfeld (1999, page: 172)
. In fact there are many resemblances between both taxa, some of them presented in
Table 1
. The most notable feature shared by them is the peculiar shape of unguis, with a cavity and with some internal serration. However the genera differ in the shape of this structure. Also in
Gisinurus
the antennae are as long as body (versus shorter than body); Ant. IV bears 13 intermediate subsegments (versus 9); the posterior dental chaetae formulae is 3,2,2,2,2,1,1 (versus 3,2,1 …1); and the mucronal edges are coarsely serrate (versus smooth).
The unguis shape and other morphological features (especially chaetotaxy) suggest phylogenetic proximity of
Varelasminthurus
gen. nov.
and
Gisinurus
,
Songhaica
,
Dietersminthurus
and
Soqotrasminthurus
(comparison in
Table 1
). However, only a detailed phylogenetic analysis can provide a clear understating of the validity of these characters in evolutional approaches, and the relations of these genera among each other and among the
Sminthurinae
.
The discovery of a new genus of
Sminthurinae
in the Atlantic Forest, within an area never studied before and clearly disturbed by human colonization points out how little is known about the Brazilian fauna and how potentially rich in number of collembolan taxa the Neotropical Region is. Even though the
type
locality of
Varelasminthurus
gen. nov.
, “Parque Estadual
Mata
de Pipa”, is an small area of environmental protection, it is located in Pipa Beach, Tibau do Sul, a highly visited region due to international tourism. This contrasting conditions show how urgent is the necessity to unveil the Brazilian fauna and to create better policies to protect it.