Stemmiulus brasiliensis n. sp., a new species of millipede from Brazilian iron ore caves (Diplopoda: Stemmiulida: Stemmiulidae)
Author
Iniesta, Luiz Felipe Moretti
Author
Ferreira, Rodrigo Lopes
text
Zootaxa
2015
3964
5
546
552
journal article
10.11646/zootaxa.3964.5.4
c9acf904-3148-4908-b111-7e90ea9b45de
1175-5326
236366
07FD1A2E-2841-431E-9359-E4295C5F6B0E
Stemmiulus brasiliensis
Iniesta & Ferreira
,
sp. nov.
(
Figs 2–5
)
TYpe
.
Holotype
male (
ISLA
5681), SL22 cave (Serra Leste
5°57’39.14’’S
,
49°38’03.51’’N
), Curionópolis/PA,
Brazil
, 2010, leg. M. P. Oliveira.
Paratypes
:
2 males
(
ISLA
3701, 5682), SL51 and SL22 caves, Curionópolis/PA,
Brazil
, 2010;
2 females
(
ISLA
5683), SL22 cave, Curionópolis/PA,
Brazil
, 2010, all leg. M. P. Oliveira.
Name.
To emphasize
Brazil
, the
terra typica
.
FIGURE 2.
Stemmiulus brasiliensis
sp. nov.
, A) live paratype female; B) anterior part of body, a fixed paratype female.
Comparative diagnosis.
Stemmiulus brasiliensis
sp. nov.
is distinguished from the other Brazilian species by the peculiar cephalic chaetotaxy pattern of the male and the different gonopod structure (cf.
Mauriès 1984
). The species
S. adisi
,
S. amazonicus
and
S. wellingtoni
all show complex gonopod conformations compared to
S. brasiliensis
sp. nov.
The differences are especially clear in angiocoxite (
Ag
) and colpocoxite (
K
) structure. The species
S. wellingtoni
has a trifurcate
Ag
tip while the latter in the other species is either bifid or, like in
S. brasiliensis
sp. nov.
, unipartite. In
S. adisi
, the tip of
Ag
is wider distally and shortened laterally while
S. amazonicus
has a diagonal/digitiform tip and a wider apex. In
S. brasiliensis
sp. nov.
,
Ag
is highly distinctive, being tiny and devoid of a differentiated tip.
K
in the new species is also different, elongated, irregular in shape and membranous at apex, versus wide and with some apical projections in
S. adisi
, rounded and thin in
S. amazonicus
or thin and more strongly curved mesad in
S. wellingtoni
.
FIGURE 3.
Schematic drawings of head of
Stemmiulus brasiliensis
sp. nov.
A) Male paratype; B) Female paratype.
Measurements.
Length from
8.33 to 12.15 mm
; maximum midbody diameter between
0.68 to 0.92 mm
; body with 35–41 rings, plus 1–2 apodous before telson.
Description of adults.
General characteristics
: Head and body brownish. Head with different chaetotaxy patterns in male (
Fig. 3
A) and female (
Fig. 3
B). One large ocellus on each side of head. In length, antennomere 1 <3 = 4 ≈ 5 = 6 <2. Ozopores located dorsolaterally and starting with fifth body ring. Lateral region of tergites with parallel striations, including above ozopore. Telson with 3+3 evident spinnerets. Gnatochilarium rounded in male: stipes enlarged and curved, mentum triangular, lamellae linguales striated, with 1+1 setae; females with a square gnatochilarium: stipes straight, mentum subtriangular, lamellae linguales non-striate. Trunk with a dorsal axial suture and line; a clear lateral line on each side.
Male characteristics:
First to third pairs of legs modified. Legs 1 with enlarged coxae, these apparently fused to prefemur, also beset with long ventral setae; femur elongated, with short ventral setae and one especially long seta; postfemur and tibia similar, with long ventral setae; tarsus elongated, with a ventral row of short setae reaching the claw. Legs 2 (
Fig. 4
A, B) with a coxosternal lobe (
Lcs
) beset with short setae;
Lcs
rounded and supporting some long distal setae in oral view; telopodite (
1°, 2° Tp
) elongated and digitiform, beset with short setae; coxosternal process (
Pcs
) acute and elongated. Legs 3 (
Fig. 4
C, D) with a non-enlarged
Cx
;
Pf
,
F
,
Psf
and
Tb
with long ventral setae and square in shape;
T
with long dorsal setae, nine ventral spatulate setae (
Ss
) and four long setae around the tarsal claw. No paragonopods (ninth pair of leg) were found, perhaps vestigial (reduced) or non-existent in this species. Gonopods elongated (
Fig. 5
A, B), with basal section wider than distal one;
Cx
fused to sternum, with two large, rounded, gonopodal processes. Distal region with two well-developed extensions: a long and slender angiocoxite (
Ag
) resembling a thin shell adhered to colpocoxite (
K
) and carrying short setae in distal portion.
K
with curved setae in the latter portion; tip with a membranous area (
Ma
) surrounding the end of a seminal groove (
Sg
).
Sg
visible at
K
beginning with junction of gonopodal segments. Both
Ag
and
K
with thick edges.
Notes.
The new species can be recognized, in males, by a slight difference in head chaetotaxy. In the Brazilian species, the first row of setae is close to the occipital suture, the row being composed of 4 setae, as observed in
S. brasiliensis
sp. nov.
,
S. amazonicus
and
S. wellingtoni
, or 2 setae (maybe 2+2 dislocated), as in
S. adisi
(cf.
Mauriés 1984
). Furthermore, there are other, straight or diagonal rows. These setae are arranged mainly near the suture on the clypeus, on the frons and labrum (
Silvestri 1916
;
Mauriès 1984
).
As regards the gonopod, the genus
Stemmiulus
shows remarkable variation between the species, mainly in
Ag
and
K
structure (
Chamberlin 1952
;
Loomis 1964
;
Hoffman 1977
;
Mauriés 1979
,
1989
;
Mauriès & Golovatch 2006
;
Mauriès
et al
. 2010
). According to
Mauriès (1989)
, most of the American species have a distolaterally expanded
Ag
. The species
S. amazonicus
,
S. wellingtoni
and
S
.
adisi
share this trait (
Mauriés 1984
), but the new species has no evident expansion. The
Ag
structure in
S. brasiliensis
sp. nov.
seems to serve as a lateral shield to
K
.
In the Brazilian species of
Stemmiulus
, males generally show no meaningful differences in leg structure, although there is some variation in the second and third pairs. All Brazilian species are similar in leg 1 conformation. The second pair is the most strongly reduced. In
S. brasiliensis
sp. nov.
,
Cx
is very different from that in the other species. Both
S. adisi
and
S. amazonicus
show a kind of shoulder while such a structure is absent from
S. brasiliensis
sp. nov.
In all Brazilian species,
Cx
is large, yet without
Lcs
in
S. adisi
,
S. amazonicus
and
S. wellingtoni
, while
Tp
digitiform. However, its outline slightly varies between the species. In leg 3 structure,
S. brasiliensis
sp. nov.
is notably different, mainly in
Pf
and
F
which are not enlarged.
The size and number of body segments can vary between species. In the Brazilian species, this number ranges from 42 to 53 (
Mauriés 1984
). In
S. brasiliensis
sp. nov.
, the body is with 35–41 rings. This variation is common within the order, with extremes found in S
temmiulus annulatus
Silvestri, 1916
(38 segments, regardless of the new species described herein) and
S. diversicolor
Loomis, 1964
(54 segments) (
Silvestri 1916
;
Loomis 1964
). Although there are few studies concerning stemmiulidan ontogeny, the development can be recognized as euanamorphotic (
Mauriés 1984
;
Enghoff
et al
. 1993
).