Species l.    C. alchichica Acosta & Prat 2017.

Male: Total length 4.34 (3.95-5.07) mm; Wing length 3.53 (2.99-4.25) mm.
Coloration: Head yellowish brown, thorax dark brown.  Abdomen pale brown with dorsal dark markings on TI-VII, wider on TVIII.  Legs uniformly pale yellow.
Head: AR 3.79 (3.75-3.83); clypeus with 15-20 setae; 30-40 temporal setae.  Palps (segs 2-5) 47 : 171 : 189 ; 245; P5/P4 1.30; P5/P3 1.43.
Wings transparent without setae, anterior veins pale brown, r-m crossvein and C, M, R1, R4+5 dark brown.  Squama with 20-26 setae, 2 SCf on brachiolum. VR 0.94 (0.91-0.95).
Leg lengths (micron) and proportions:
 

	Fe	Ti	Ta1	Ta2	Ta3	Ta4	Ta5	LR	F/T	BR
PI	1088	1081	1579	860	580	470	220	1.03-1.27	0.97-1.01	1.9
PII	1224	1223	715	440	321	203	148	0.56-0.60	1.01-1.08
PIII	1446	1519	995	609	440	263	164	0.66-0.71	0.93-0.96

Setae on TIX not clear; anal point narrowing to end; Superior volsella of type E of Strenzke 1959); Inferior volsella about to end of anal point, apparently with simple setae.  Gonostylus moderately swollen and narrowing significantly over distal third, 6-7 setae at distal end.

Male hypopygium of C. alchichica from Acosta et al. 2017

Female: Not described.

Pupa: Length of abdomen 5.4 (4.9-6.2) mm.  Cephalic tubercles (males?) conical 145.2-209.7 µm; no mention of frontal warts.  Basal ring of thoracic horn 122.4 (107.4- 137.6) µm. Thorax scarcely granular.  Abdomen without dorsal shagreen patches evident.  Hooks at posterior of segment II continuous but not counted.  Pedes spurii B and A well developed on segments II and IV respectively.

Pupal spur of C. alchichica from Acosta et al. 2017

Spur of segment VIII with 5-6 closely applied teeth; more than 115 taeniae in anal fringe, apparently in multiple rows.

Larva a small plumosus-type about 9-10 mm in length, ventral tubules appear relatively short.
Ventral head length 0.28 (0.26-0.31) µm.  Gula slightly darkened, slightly wider than the mentum and widest part way up from posterior margin.

Larval mouthparts of C. alchichica from Acosta et al. 2017

Mentum of type II and median tooth of type III; ventromentum with a smooth outer margin, VMR perhaps about 0.17, striae not counted.
Premandible with outer tooth very narrow and coming to a sharp point, inner tooth about 6 times wider but still coming to a relatively sharp point (type B2).  Pecten epipharyngis with 13-14 teeth (type A).
Antenna with basal segment about 3 times longer than wide, RO about 1/3 up from base (0.23, 0.18-0.29).  Segment proportions 118 : 30 : 8.5 : 16 : 8, AR 1.9 (1.69-2.39).
Mandible of type IIB, number of taeniae in PecM not given, nor the presence or number of furrows at the base, MTR about 0.43.

Cytology:  Four polytene chromosomes with the thummi-cytogroup combination, AB, CD, EF, G.  Centromeres clearly visible and heterochromatic.  Arm G with 2 BRs and an NOR, partially unpaired; Bulb of arm B (groups 8-7) near the telomere.
NORs also on arm C (in some cells) and arm D, both near the centromere.

alchA1:    1, 13 - 16, 2c, 10 - 12, 3 - 2d, 9 - 4, 17 - 19.
alchB1:    Puff with proximal dark bands)(7-8) near telomere.
alchC1:    Constriction (2-5b) near distal end of arm.
alchD1:   NOR near centromre.
alchE1:    1 - 3e, 10c - 3f, 4 - 10b, 5, 11 - 13;                            Inv5-10 from maturus, 'proulxi', etc.
alchF1:    1 - 8c, 12 - 17, 10 - 8d, 11, 18 - 23.
alchG1:    terminal NOR, nearby small BR and a large subterminal BR near the other end.

Polytene chromosomes of C. alchichica from Acosta et al. 2017

Molecular:
mtCOI: Barcode sequence of seven specimens are in GenBank: MG603057-63.These sequences indicate a relationship to species of the C. decorus-gp, particularly, C. 'proulxi' and C. 'butleri'.

Found:  (Type locality), Lake Alchichica (19.412°N, -97.400°W), Puebla, Mexico.