The Dixa inextricata Dyar & Shannon (Diptera: Dixidae) species group, with two new cryptic species from the eastern Nearctic Region
Author
Moulton, John K.
text
Zootaxa
2016
4121
4
458
472
journal article
38894
10.11646/zootaxa.4121.4.6
4247868c-80b8-43b6-9ef7-7feced83afe1
1175-5326
265286
F15F9CC4-A5CE-45D9-94F7-7C112AE71544
Dixa calciphila
sp. nov.
(
Figs 3–4
,
10
,
15–17
,
23
)
Type
material
.
HOLOTYPE
♂, labeled: “
USA
:
TN
:
MARION COUNTY
/ Spr @
US
64/TN41 opposite Raccoon Mtn/
N35°03′31″
W85°29′08″
,
243 m
/
24.iv.2014
/ J.K. Moulton”; “
HOLOTYPE
/
Dixa
/
calciphila
/ J.K. Moulton [red label]” (
CNC
).
PARATYPES
: Same data as
holotype
, 5♂ and 2♀ each to
CNC
and
USNM
.
Additional material examined
.
USA
:
KENTUCKY
:
EDMONSON COUNTY
, Mammoth Cave NP, Cinnamon Fern Bog, UV light trap,
7.vi.2007
, C. Parker & J. Robinson (1♂,
USGS
); Thru Sprs, UV light trap,
15– 16.viii.2006
, C. Parker & J. Robinson (3♂,
USGS
).
HART
COUNTY
, Three Hundred Sprs nr Munfordville,
N37°17′29.85″
W85°43′45.70″
,
29.ix.2008
, JKM—1♂. Unnamed trib Lynn Camp Crk,
10.iv.2008
, JKM—1♂.
TAYLOR COUNTY
, Little Angel Spr, Trib Craig’s Crk, N of Campbellsville,
N37°26′40″
W83°21′18″
,
9.vi.2005
, JKM;
1.vii.2004
, Malaise trap, G.K. Weddle—2♂.
17.iv.2005
, JKM—1♂, 1♀, 1L;
15.ix.2005
—1♂.
TENNESSEE
:
FRANKLIN COUNTY
, Trib
Turkey
Crk, ex TN Rt 16 (Old Turnpike Rd.), Walls of Jericho SNA,
N34°59′40.77″
W86°03′38.98″
,
23.v.2008
, JKM—1♂.
MARION COUNTY
, Spr @
US
64/TN41 opposite Raccoon Mtn,
243 m
,
N35°03′31″
W85°29′08″
,
24.iv.2014
, JKM—20♂, 7♀;
4.ix.2015
—5♂, 2♀. Daniel Cave Spr,
N36°26′00″
W85°48'00.00″
,
8.ix.2010
, JKM—3♂.
MORGAN COUNTY
, Frozen Head SP, Flat Frk,
N36°07′10.91″
W84°27′52.67″
,
20.vi.2014
, JKM—1♂. Obed Wild and Scenic R NP, Melton Mill Br @ Footbridge, Point
Tr
. below Lilly Bluff Overlook,
357 m
, UV light trap,
6.ix.2005
, C. Parker (2♂,
USGS
).
PUTNAM COUNTY
, Tayes Hollow Spr. @ TN Rt. 84, S of Monterrey,
498 m
,
N36°08′12″
W85°17′28″
,
17.iv.2010
, JKM—1♂, 2♀, 1L;
7.iii.2009
—4♂ & 2♀;
10.iii.2009
—3♂, 1♀, 6L;
31.iii.2013
—6♂, 4♀, 4L,
2P.
FIGURES 9–11
. Male terminalia, lateral view, in non-rotated (dorsal-ventral) orientation.
9
,
Dixa appalachiensis
sp. nov.
;
10
,
D. calciphila
sp. nov.
;
11
,
D. inextricata
.
Scale bar = 50 µm.
FIGURES 12–20
. Male terminalia.
12
,
Dixa appalachiensis
sp. nov.
, lateral view (rotated);
13
,
D. appalachiensis
sp. nov.
, ventral view;
14
,
D. appalachiensis
sp. nov.
, terminal view;
15
,
D. calciphila
sp. nov.
, lateral view (rotated);
16
,
D. calciphila
sp. nov.
, ventral view;
17
,
D. calciphila
sp. nov.
, terminal view;
18
,
D. inextricata
, lateral view (rotated);
19
,
D. inextricata
, ventral view;
20
,
D. inextricata
, terminal view. Scale bar = 50 µm.
Diagnosis
. This species can be distinguished from
D. appalachiensis
sp. nov.
and
D
.
inextricata
by the following characters:
Morphological
. Ventral margin of gonostylus strongly convex; basal gonocoxal lobe with apex noticeably acuminate; cercus narrow, acuminate, as long as lateral width of proctiger.
Molecular
. Among the most significant differences within the 66 nucleotides (22 codons) shown (
Fig. 38
) that serve to distinguish this species from the other two are amino acid substitutions at the following codon positions: 2 (valine/methionine), 3 (alanine/proline), 14 (asparagine/serine), 18 (asparagine/serine), 19 (arginine-CG)/arginine-AG or lycine), and 21(glycine/absent).
Description
.
Male
(
Fig. 3
). Same as
D. appalachiensis
sp. nov.
, except as follows: Wing length (
n
=13) 2.6– 3.1 (avg=2.9) mm. Wing darker smoky gray.
Thorax
generally darker brown (
Fig. 3
), most distinctly differing in katepisternum concolorous with head, anepisternum, and anepimeron and contrasting sharply against whitish to straw-colored mesocoxa. Meron brown, nearly as dark as katepisternum.
Terminalia
(
Figs 10
,
15–17
,
23
): 9S lightly sclerotized, with straight anterior margin. Proctiger heavily sclerotized (
Figs 15–17
,
23
). Cercus narrow, acuminate, as long as lateral width of proctiger (
Figs 10
,
15
). Basal gonocoxal lobe directed posterodorsally in lateral view with apex distinctly falcate (
Fig. 10
), appearing rectangular in ventral (
Fig. 16
) and terminal views (
Fig. 17
). Apical gonocoxal lobe blunt, directed mediolaterally, in lateral view appearing ca. 1/
5X
or less of gonostylus length (
Figs 10
,
15
). Gonostylus triangular in lateral view, ca. 1.3–1.5X longer than greatest depth, ventral margin noticeably convex, bulbous (
Fig. 10
).
Female
(
Fig. 4
). Wing length (
n
=4) 2.9–3.2 (avg=3.0) mm. Not reliably separated from
D. appalachiensis
sp. nov.
or
D. inextricata
.
Etymology
. Named for the karst geography (
calc
- = lime + -
phil
= loving) that largely defines the region in which it occurs.
Distribution
. Currently known only from Kentucky and Tennessee (
Fig. 37
).
Remarks
. This species is known from streams ranging from small first order hillside trickles (
Fig. 33
) to raging torrents (
Fig. 34
) originating from underground streams. In central Tennessee adults are already on the wing by early March, earlier than other dixids found in the region. This species has been collected in association with
Dixa fusca
,
D. modesta
sensu Peters
,
Dixa
nr.
repanda
Peters, and a member of the
Dixella indiana
complex. This species is expected to occur in northeastern Alabama and possibly, southern
Indiana
. Morphologically and molecularly, this species is more distantly related to the other two species in the group than they are to one another.