The spider Micrathena shealsi Chickering, 1960 (Araneae, Araneidae): description of the male, with new data on its geographic distribution
Author
Argañaraz, Carina I.
Author
Rubio, Gonzalo D.
text
Zootaxa
2011
3104
52
58
journal article
45954
10.5281/zenodo.207326
a3151bb7-5427-4cb7-9a2f-868e0dc04d53
1175-5326
207326
Micrathena shealsi
Chickering, 1960
(
Figs. 1–18
; Map 19)
Micrathena shealsi
Chickering, 1960a
: 8
, figs. 13–17 (
Holotype
female from Sunchal,
Argentina
, deposited in Invertebrate Zoology Collection of Museum Comparative Zoology—MCZ 23053, not examined).
Micrathena shealsi
:
Levi, 1985
: 458
, figs. 74–78;
Platnick, 2011
.
New records.
ARGENTINA
:
Jujuy
: Yala (
24º07'13''S
,
65º27'24''W
,
1888m
.a.s.l.),
20 May 1983
(P. Goloboff),
1 female
(MACN-Ar 25178); Calilegua, Parque Nacional Calilegua, Seccional Aguas Negras (
23º45'43.3''S
,
64º51'04.7''W
,
605m
.
a.s.l.),
27–31 January 2009
(M. Izquierdo, L. Zapata & M. Akmentis),
1 male
(MACN-Ar 27850); same loc., near Monolito (
23º40'27''S
,
64º54'01''W
,
1714m
.a.s.l.),
19 October 2009
(G. Rubio & M. Pocco),
1 female
(MACN-Ar 27851).
Salta
: Quebrada de San Lorenzo, site 1 (
24°42'51.84"S
,
65°31'6.96"W
,
1833m
.a.s.l.),
26–28 April 2006
(G. Rubio, J. Corronca, B. Cava, V. Olivo & A. González-Reyes),
2 females
(MACN-Ar 27852); same loc., site 2 (
24°43'9.60"S
,
65°30'56.40"W
,
1691m
.a.s.l.), same date (same leg.),
6 specimens
(IEBI); same loc., site 3 (
24°43'16.80"S
,
65°30'39.00"W
,
1587m
.a.s.l.), same date (same leg.),
1 specimen
(IEBI); same loc., site 4 (
24°43'17.04"S
,
65°30'25.80"W
,
1575m
.a.s.l.), same date (same leg.),
2 specimens
(IEBI); same loc., site 5 (
24°43'16.32"S
,
65°30'7.92"W
,
1560m
.a.s.l.), same date (same leg.),
7 specimens
(IEBI); road to El Carmen, site 1 (
24°31'13.36"S
,
65°21'4.02"W
,
1547m
.a.s.l.), same date (same leg.),
2 specimens
(IEBI); same loc., site 2 (
24°30'33.30"S
,
65°20'27.13"W
,
1587m
.a.s.l.), same date (same leg.),
1 specimen
(IEBI); same loc., site 3 (
24°30'15.84"S
,
65°20'11.40"W
,
1516m
.a.s.l.), same date (same leg.),
2 specimens
(IEBI).
Tucumán
: Cochuna (
27°19'19.97"S
,
65°55'38.01"W
,
1162m
.a.s.l.),
25 March 2011
(C. Argañaraz),
1 male
(MACN-Ar 27853); same loc., 0
9 April 2011
(C. Argañaraz & G. Rubio),
4 males
,
6 females
(MACN-Ar 27854), and
1 male
(MACN-Ar 27856); monument to El Indio (
27° 2'54.24"S
,
65°40'8.76"W
,
1065m
.a.s.l.),
21 February 2011
(G. Rubio & L. Acosta), 1 sub-adult male (MACN-Ar 27855).
Diagnosis.
Males of
M. shealsi
(
Figs. 1–7
,
9–15
) resembles
M. bifida
(Taczanowski)
from
Peru
by general habitus, and by the palp bearing a tegulum lobe in ectal view (
Levi 1985: figs. 45, 47
) but it can be distinguished from it by the palpal morphology (
Figs. 5–7
,
9–13
) (
M. shealsi
has a distinctive shape of the median and terminal apophyses,
Fig. 6
,
10
). Females of
M. shealsi
differ from congeners by the absence of a scape on the epigynum (
Fig. 16
) and by the ventral coloration (light sternum, and depigmented median area of the abdomen venter:
Levi 1985
).
Micrathena shealsi
was erroneously taken as “
M. nigrichelis
with scape of epigynum torn off” (
Levi 1985
). However, these species can be easily separated by the above-mentioned chromatic pattern (
Levi 1985
), and by the dimensions of the cephalic region (smaller in
M. shealsi
); the latter feature is also present in males.
Description.
Male
from Cochuna, Tucumán (MACN-Ar 27856): Carapace orange (in nature—Fig. 18) or yellowish (in alcohol), black on sides and with a blackish longitudinal strip starting near the posterior eyes towards thoracic groove (
Figs. 1
,
18
). Very shallow dimples on each side of thoracic groove. Chelicerae pale yellow. Sternum and coxae light yellow, with dark pigment near the articulation. Legs orange-brown, first pair darker. Coxa I with hook, femur II with groove (
Figs. 14–15
). Tibia I-II with macrosetae; ventral side of femur II with row of 8–9 spines. Abdomen longer than wide, rectangle-shaped, without humps; yellowish-white dorsally (slightly orange in nature) with three black marks on each side, one dark median longitudinal strip on posterior two thirds; end of abdomen black; venter between epigastric furrow and spinnerets pale yellow, spinnerets and the rest of venter black-grayish (
Fig. 3
). Palp with reddish-brown general color (
Figs. 17–18
). Body total length from AME to tip of abdomen 5.51; carapace length 2.10, width 1.47; sternum length 0.91, width 0.52; abdomen length 3.57, width 0.98. Leg formula I/IV/II/III. Leg lengths (I/II/III/IV): femur 2.03/1.78/1.12/2.17; patella 0.64/0.58/0.38/0.49; tibia 1.54/1.22/0.63/1.20; metatarsus 1.15/1.12/0.56/1.33; tarsus 0.63/0.63/0.35/0.66; total leg 5.99/5.33/3.04/5.85.
Female
(
Holotype
, MCZ 23053): See
Chickering (1960a: 8, figs. 13–17)
. Internal genitalia as in figure 8.
Variation.
Males
(n=6): Body total length 4.83–5.51; carapace length 2.03–2.17, width 1.4–1.5; sternum width 0.50–0.56; abdomen length 3.01–3.57, width 0.87–1.05. Total leg (I/II/III/IV) 5.98–6.12/5.28–5.37/3.01–3.11/ 5.85–6.04.
Natural history
(
Figs. 17–18
). Males of
M. shealsi
were found in most cases on the upper periphery of the female webs, hanging from a silk line. In only one case, a male was found in a small orb-web located under the female site. Females of
M. shealsi
sometimes build their web near other female webs, forming groups (of 2 to 5 individuals) in the lower stratum of vegetation, no higher than
60 cm
. In such cases males were not observed. Ongoing ecological research (G. D. Rubio, unpublished) suggests that this species is strongly associated with the Yungas rainforest habitat.
Geographic distribution
(
Fig. 19
).
Micrathena shealsi
was only known from the
type
locality “Sunchal,
Argentina
” (
Chickering 1960a
). Although
Levi (1985)
assigned this locality to Salta Province, “Sunchal” in the latter does not fall within the rainforests region (
Fig. 19
); in contrast, “Sunchal” or “El Sunchal” in Tucumán Province, seems more likely for a rainforest-dwelling spider. New records here provided reveal that
M. shealsi
has an extensive distribution in the Yungas, corresponding to the higher altitudinal belt (~
1700 m
.) of the mountain forests and rainforests from Tucumán, Salta and Jujuy Provinces (
Fig. 19
).