New species of subgenus Megaluracarus (Acari: Hydrachnidiae: Arrenuridae: Arrenurus) from Mexico
Author
Ramírez-Sánchez, Marcia M.
Author
Rivas, Gerardo
text
Zootaxa
2013
3718
4
317
330
journal article
42984
10.11646/zootaxa.3718.4.2
e1faacdd-41f0-4693-a17a-d90cc7a6c330
1175-5326
218297
C7C06AE3-FBAB-4640-9935-CB81059BDB05
Arrenurus (Megaluracarus) urbanus
sp. nov.
(
FIGURES 1
D, 2D, 3D, 4G–H, 26–32)
Type
material.
Holotype
male from Cuemanco canal, Xochimilco ecological park,
Mexico
City, 2242 masl,
19º17’20” N
99º06’06” W
,
27 October 2001
, coll. J. Cime and G. Rivas.
Paratypes
:
Two females (one of them same data as
holotype
) and two males (CNAC007183), same locality as
holotype
,
16 December 2001
, coll. J. Cime and M. Ramírez-Sánchez.
Diagnosis.
Idiosoma margins smooth, cauda moderately long, slightly constricted at its base and proportioned with the anterior idiosoma (
Fig. 1
D). Idiosoma and cauda bulky in lateral view (Fig. 2D). P-II medially with a characteristic patch of two
types
of setae: Needle and snake-shaped (
Fig. 28
). The idiosoma and appendages intense greenish blue, without pale areas in the integument.
Description.
MALE: Idiosoma 693 (729–735) long and 467 (441–473) wide; anterior idiosoma margin rounded (
Fig. 1
D). Greatest width of dorsal shield 368 (357–378); dorsal shield length including cauda 609 (620– 646); non-caudal portion bearing the postocularia and three pairs of glandularia, D2 setae well separated from its corresponding glands; D3 setae and glands close to each another and located rostral to its widest portion (
Fig. 26
). Cauda moderately long in proportion with anterior idiosoma (
Fig. 1
D), 189 (210–220) long, slightly constricted at its base, proximal width of cauda 247 (257), distal width of cauda 278 (284); posterior margin rounded and smooth when viewed dorsally; in lateral view, cauda thicker at its base than the anterior idiosoma (Fig. 2D, 27). First coxae with sharp but not projecting anterior corners (
Fig. 3
D); second coxae with blunt corners; second and third coxae separated by two rows of body pores; medial margin of third and fourth coxae parallel, with
FIGURES 26–32.
Arrenurus (Megaluracarus) urbanus
sp. nov.
;
26
–
30
: Holotype male,
31–32
: Paratype female.
26.
Idiosoma, dorsal view;
27.
Idiosoma, lateral view;
28.
Palp, medial view;
29.
I-Leg-5–6;
30.
IV-Leg-4–6;
31.
Idiosoma, dorsal view;
32.
Idiosoma, ventral view. Scale bars 100 mm.
posterior corner squared; posterior margin of fourth coxae straight. Acetabular plates of moderate size extending straight out from genital opening and reaching posterior angles of fourth coxae; a few hairs on the posterior margin of fourth coxae but they are not visible in dorsal view. Dorsal lengths of palpal segments (
Fig. 28
): P-I 25 (28–30); P-II 65 (65–69); P-III 43 (33–38); P-IV 68 (65–68); P-V 38 (30–32). P-II medial bears a patch of numerous long needle-shaped setae and four snake-shaped setae; P-IV distoventral portion angular, with a relatively large antagonistic seta,
28 in
length. Dorsal lengths of distal segments of first leg (
Fig. 29
): I-Leg-4 94 (90–93); I-Leg-5 90 (93–95); I-Leg-6 120 (125–138). Dorsal lengths of distal segments of fourth leg (
Fig. 30
): IV-Leg-4 120 (125), 170 (178) to tip of distal extension; IV-Leg-5 133 (125); IV-Leg-6 165 (185–188); III-Leg-3 and 4 with long, stiff swimming setae; the IV-Leg-4 distal process bears four thick, somewhat wavy swimming setae; IV-Leg-3 and 5 bear long stiff, swimming setae; dorsal surface of IV-Leg-5 bears three short, spine-like setae placed in a straight line.
FEMALE: Idiosoma 788–809 long, 651–662 wide; both anterior and posterior margins rounded (
Fig. 4
G). Dorsal shield 663–683 long and 515–536 wide, bearing the postocularia and three pairs of glandularia (
Fig. 31
). Acetabular plate region 420–425 wide; acetabular plates laterally directed, short, bowed and narrow in relation to gonopore length; gonopore 189 long and 179 wide; one and a half rows of idiosoma pores between second and third coxae, three rows between left and right posterior coxae (
Fig. 4
H, 32). Dorsal lengths of palpal segments: P-I 29–30; P-II 68–71; P-III 41–43; P-IV 69–70; P-V 30–34. Palp structure and chaetotaxy as in the male. Dorsal lengths of distal segments of first leg: I-Leg-4 (91–95); I-Leg-5 (88–94); I-Leg-6 (115–125). Dorsal lengths of distal segments of fourth leg: IV-Leg-4 (140–150); IV-Leg-5 (163–168); IV-Leg-6 (175–195); IV-Leg-3 and 4 bear considerably long, stiff swimming setae; IV-Leg-5 and 6 bear numerous short swimming setae; dorsal surface of IV-Leg-5 bears three short, spine-like setae placed in a line.
Etymology.
The name refers to the urban conditions surrounding the Xochimilco natural reserve, where the specimens were collected.
Discussion.
The P-II chaetotaxy of
Arrenurus urbanus
sp. nov.
is complicated, as it consists of a mixture of two
types
of setae, i.e., many long needle-shaped setae and four snake-shaped setae.
Arrenurus spathulifer
Lundblad
from
Argentina
,
Brazil
,
Paraguay
and
Uruguay
(Lundblad, 1944) presents very similar palp chaetotaxy and idiosoma shape to
A. urbanus
, except that in
A. spathulifer
the cauda is not constricted at its base.
Arrenurus willinki
Rosso
de Ferradás 2000 from
Argentina
and
Uruguay
, and
Arrenurus brevicaudatus
Viets 1936
known from
Argentina
,
Bolivia
,
Brazil
,
Colombia
,
Guyana
,
Peru
,
Uruguay
and
Venezuela
, also exhibit a mixture of two
types
of setae in the palp, but considerably fewer than
A. urbanus
; in those species, the dorsoglandularia position and the general shape of idiosoma are also similar to
A. urbanus
, but the proportions of the cauda are different among the three species.