New records of water mites (Acari: Hydrachnidia) from Brunei Darussalam, Borneo, with descriptions of two new species
Author
Pešić, Vladimir
Author
Chatterjee, Tapas
Author
Marshall, David J.
Author
Pavićević, Ana
text
Zootaxa
2011
3018
50
58
journal article
46379
10.5281/zenodo.278661
1144eebf-bbaf-4412-923a-ab0014b5d5d8
1175-5326
278661
Litarachna bruneiensis
sp. nov.
(
Fig. 4
)
Type
series.
Holotype
, male,
Brunei Darussalam
, Kota Batu, Sangai
Brunei
Estuary and Bay,
4º56'N
,
115º1'E
,
10.iii.2011
, mud flat and mangroves, leg. T. Chatterjee & D. J.
Marshall
.
Paratypes
:
7 males
,
14 females
, 4 deutonymphs, same data as
holotype
, one male, two females and one deutonymph dissected and slide mounted in Hoyer's fluid.
Diagnosis.
The lateral apodemes of Cx-IV shorter than medial apodemes, the latter of moderate length; P-2 ventrally with small triangular extension, P-2 L 70–90 µm in both sexes, ventrodistal angle of P-3 ending in a small pointed tubercle.
Description.
Male (
holotype
, in parentheses measurements of
paratype
). Idiosoma L/W 306/225 (303–372/ 216–306, n = 3). Cx-I separated medially. Suture lines Cx-I/II and Cx-III/IV complete, suture lines Cx-II/III incomplete. Posterior margin of Cx-IV strongly concave, with two pairs of apodemes; the lateral ones shorter than the medial ones, the latter of moderate length. Genital field L/W 38 (40)/32 (31), consisting of a sclerotized ring with 2–3 setae on each side. Posterior, lateral and anterior reaches of genital field with numerous setae (
Fig. 4A
). A pair of large glandularia-like platelets with one large and two small pores and three pairs of wheel-like acetabula (sensu
Cook 1996
) or specialized glandularia (sensu
Tuzovskij 1978
) posterior to genital field. Two of these wheel-like structures large with many radiating spokes, the most posterior small with less radiating spokes. Excretory pore unsclerotized, near the posterior idiosoma margin. Palp (
Fig. 4D
), dL: P-1, 15; P-2, 66 (63); P-3, 34 (35); P-4, 75 (75); P-5, 25 (26); P-2/P-4 L ratio 0.88 (0.84); P-2 with ventrally with small triangular extension, P-3 ventrodistal angle ending in a small pointed projection, P-4 slightly curved and without setal tubercles. Legs: dL of I-Leg-4–6 (
Fig. 4F
): 44 (49), 60 (66), 72 (80); dL of IV-Leg-4–6: 103 (102), 112 (110), 99 (103); III-Leg-4 with 1 swimming seta, III-Leg-5 with 2 swimming setae, IV-Leg-4 with one swimming seta, IV-Leg-5 with 2 swimming setae.
FIGURE 4A–I
.
Litarachna bruneiensis
sp. nov.
(A, C–F = male, B, G–H = female, I = deutonymph): A–B, I = idiosoma, ventral view; C = gonopore; D = palp; E = ejaculatory complex; F = I-Leg-5 and -6; G–H = palp (P-1 missing). Scale bars = 100 μm.
Female (n = 2): similar to male, except for shape of the genital field. Idiosoma L/W 297–309/236–250, n = 3 (ovigerous females: L/W 403–447/328–381, n = 2). Genital field L/W 54–62/43–50), pregenital and postgenital sclerite fused, forming a complete ring around the gonopore (
Fig. 4B
). Palp (
Figs. 4G–H
) dL: P-2, 72; P-3, 34–35; P-4, 76–85; P-5, 25–27; P-2/P-4 L ratio 0.85–0.95; palp setation as in male. Legs: dL of I-Leg-4–6: 45–48, 60–65, 71–75; dL of IV-Leg-4–6: 101–107, 109–117, 102–110; number of swimming setae as in the male.
Deutonymph. General morphology as in adults, but lacking a genital field (
Fig.
4I
). Idiosoma L/W 188–219/ 133–137 (n = 2); palp: dL: P-1, 10; P-2, 39; P-3, 20; P-4, 45; P-5, 18; P-2/P-4 L ratio 0.87; dL of I-Leg-4–6: 26, 35, 45.
Remarks.
Litarachna bruneiensis
sp. nov.
belongs to the
L. halei
species group which is characterized by the presence of a ventral tubercle on P-2, the absence of ventral tubercle on P-
4 in
both sexes and pregenital and postgenital sclerite fused in the female and forming a complete ring around the gonopore. So far, three species of this group are known:
Litarachna halei
(Womersley, 1937)
from South
Australia
,
L. muelleri
Smit, 2008
from
Malaysia
and
L. triangularis
Smit 2009
from
Singapore
.
Litarachna halei
can be distinguished by very long medial apodemes of Cx-IV and larger dimensions of the palp segments (L P-4, 162 µm in male, 180 µm in female, data taken from
Smit 2003
).
Litarachna muelleri
differs in having lateral apodemes of Cx-IV as long as, or slightly shorter than, medial apodemes and with P-2 more stockier (
Smit 2008
).
Litarachna triangularis
, a species known from a single female, differs in distinctly shorter lateral apodemes of Cx-IV and a larger ventral tubercle on P-2 (
Smit 2009
). Moreover,
Litarachna bruneiensis
sp. nov.
, is characterized by the ventrodistal angle of P-3 ending in a small pointed tubercle, a character illustrated only for
L. halei
(see:
Smit 2003
, fig. 21) but not in two other species.
Almost nothing is known of the life history of members of the family
Pontarachnidae
and the larva (if it exists as a free living stage) and its host (if any) are unknown (
Cook 1996
). Two ovigerous females from our material contained a few very large eggs (maximum diameter of slide mounted egg L 213 µm), suggesting the possibility that parasitic larval stage is bypassed.
Etymology.
The species is named after the country of the
type
locality.
Habitat.
Marine littoral; specimens of
Litarachna bruneiensis
were collected from dense
Avicennia marina
(Forssk.) Vierh.
pneumatophore mat (depth about
2 m
).
Distribution.
Brunei Darussalam
; known only from the
type
locality.