Chironomus fusciceps Yamamoto 1990

as new name for Chironomus lugubris sensu Tokunaga 1938,
and Sasa & Yamamoto (1977).
Also called Chironomus thmini (misspelling of thummi?) Tokunga 1940
and Chironomus riparius Sasa & Yamamoto 1977.

In BOLD Bin: BOLD:ACH4992
This is the same Bin as C. sulfurosus, which has 99.83% homology.

(based on Yamamoto 1990)

Adult:

A dark species, similar in coloration to C. acerbiphilus and C. sulfurosus but legs and anterolateral margin of scutum paler.

Male:
Wing length 1.8- 2.6 mm, width 0.6-0.8 mm.  VR 0.91 (0.88-0.93).  Squama with 10-20 setae.
Head: AR 2.40 (2.15-2.67).  Frontal tubercle about 12.5-30 µm long, 10-15 µm wide.
Palpal proportions: 52 : 62 : 164 : 164 : 208.
Clypeus with 30-39 setae.Thoracic setae: Antepronotum without setae; acrostichals 6-16; dorsolaterals 15-27; prealars 5-7; supraalar 1; scutellars 13-30 (biserial).
Leg proportions (micron):

 
Fe
Ti
Ta1
Ta2
Ta3
Ta4
Ta5
LR
F/T
Ta5/Ti
PI
1280
980
1460
730
610
470
270
1.43-1.52
1.31
0.28
PII
1290
1100
570
340
270
200
170
0.51-0.53
1.17
 
PIII
1420
1260
800
450
380
240
170
0.63-0.65
1.13
 

At least 6 setae on TIX (only part shown).
Genitalia resembling that of C. acerbiphilus but S-type Superior volsella much stouter with 6-8 setae on base; anal point narrower at base; Inferior volsella with 20-29 long recurved setae on apical half; gonostyle with 6-8 apical setae.

Female
Coloration almost the same as the male.  Cercus brown.
Head: Antennal proportions: 134 : 88 : 106 : 100 : 244.  AR - 0.57; A5/A1 – 1.82Frontal tubercle 12.5-17.5 µm long and 10.0-15.0 µm wide.
Palpal proportions (micron): 56 : 68 : 172 : 170 : 232.  Vertex with 23-25 setae; Clypeus with 29-40 setae.
Wing length 2.2-2.9 mm, width 0.8-1.0 mm.  VR 0.85 (0.76-0.89); squama with 14-24 setae.
Thoracic setae: acrostichals 9-18; dorsocentrals 19-34; prealars 6-9; supraalar 1; scutellars 21-41.
Leg proportions (micron):


 
Fe
Ti
Ta1
Ta2
Ta3
Ta4
Ta5
LR
F/T
Ta4/Ti
PI
1370
1000
1420
690
590
470
280
1.32-1.52
1.37
0.28
PII
1360
1160
590
330
260
200
160
0.49-0.54
1.17
 
PIII
1460
1320
510
450
390
240
190
0.60-0.62
1.11
 

Genitalia almost the same as in C. acerbiphilus, but segment X separated from TIX by a slender membranous area.  Laterosternite with 3-7 setae, Segment X with 9-18 setae.

Pupa: Body dark brown, length 4.5-6.5 mm.  Cephalic tubercles acutely pointed, with subapical spine.  Abdominal segment II with a row of about 60 hooks, pedes spurii B developed.  Postero-lateral spurs of segment VIII with 1-2 spines.  Chaetotaxy and shagreen as shown in his figures.

Fourth instar larva:  A small (length - 10 mm) thummi-type larva, i.e. lacking lateral tubules.  Anal tubules well developed, of a single lobe, dorsal pair shorter than the ventral pair, which are about 3/4 the length of the posterior pseudopods.  Head uniformly dark brown.
Mentum of type I, in fact Yamamoto’s illustration suggests that the 5th and 6th laterals are reduced, central tooth could be type III.  Ventromentum not described and illustrated by olny a vague outline, which indicates they are longer than the mentum width.
Pecten epipharyngis with about 20 uneven but pointed teeth, suggesting possibly type B.  Premandible with 2 teeth, outer tooth shown as much longer than the inner tooth and only relatively narrower.
Antenna with 5 segrnents, relative lengths of segments 42 : 10 : 2 : 4: 2 ; segment A1 with a ring organ at basal 2/5.  Antennal blade long, reaching the base of 5th antennal segment, accessory blade indistinct.  AR about 2.3.
Distance between the S4 setae greater then that between the antennal bases.Mandible possibly of type IIIC, furrows not illustrated or recorded; 3 spines on inner margin; Pecten mandibularis with 10 taeniae.

Cytology:  no information.

Found in sulphur-containing water.

Found: Japan - Mount Unzen, Nagasaki Prefecture, Kyushu. (Type locality).

DNA sequence: There is one accession from GenBank which could be this species.
            Other sequences from GenBank or BOLD appear to be misidentified:
            GenBank accession number AB704937 is actually for a species of Kiefferulus
            That in the BOLD database (in BOLD Bin: BOLD:ACH4991) appears to be a species of Glyptotendipes, possibly G. tokunagai.

Noted by Yamamoto (1990) to be closely related to C. acerbiphilus and C. sulfurosus.The adult can be distinguished from C. acerbiphilus by the higher LR, and the male from C. sulfurosus by the more slender anal point.
The larva can be distinguished from C. acerbiphilus and C. sulfurosus by the uniformly dark head capsule.

DNA analyses:

If correctly identified, the barcode for C. sulfurosus has 99.73% homology, while C. acerbiphilus is in a different BOLD Bin: BOLD:AAJ4234.

MtCOI: there are sequences in GenBank: Accessions AB704938 and LC377640 (mined to BOLD database).

[ See also C. acerbiphilus; and C. sulfurosus]

[ Return to Index | Go to References ]


Modified: 23 February 2020
Access: Unrestricted
Copyright © 2015-2020, Jon Martin.