G. S. Tulloch.
A Key to the Mosquitoes of Massachusetts.
Psyche 46:113-136, 1939.

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PSYCHE
VOL. XLVI DECEMBER, 1939 No. 4
A KEY TO THE MOSQUITOES OF MASSACHUSETTS BY GEORGE S. TULLOCH, Chief Entomologist1 Massachusetts Department of Public Health Boston, Massachusetts
During the summer of 1939 the Department of Public Health of the State of Massachusetts conducted a state-wide mosquito survey with the cooperation of the Works Projects Administration. This survey was one phase in the program of a study of the general problem of encephalitis. It was initiated following an outbreak of encephalitis in man in 1938 which was traced to the eastern virus of equine en- cephalomyelitis. The identification of biting mosquitoes was made by using a key compiled by Tulloeh (1930) which was taken from Dyar (1922) and Matheson (1929) and modified to include those species reported from New England. The present key is a revision of the earlier one which has been enlarged to include the non-biting as well as the biting mosquitoes and is based on the examination of over 100,000 specimens. Although this key is restricted to the species which may be found in Massachusetts it is sufficiently inclu- sive for use in any of the New England states. It is ac- companied by illustrations of many of the characters of taxonomic importance and by a summary of the species of Culicidse which have been taken in Massachusetts. 1Grateful acknowledgment is made to the following for assistance: Dr. R. I?. Feemster, Director, Division of Communicable Diseases, Massachusetts Department of Public Health; Dr. V. A, Getting, Tech- nical Director, Massachusetts Mosquito Survey; Prof. J. C. Bequaert, Consulting Entomologist; V. A. Bell, R. P. Holdsworth, Jr., C. E. Elliott, Dr. B. W. Parker, Dr. J. W. Hawkins, G. C. Tower, H. D. Rose, and R. 0. Bohm, Entomologists and to Mr. J. Milano for preparation of the plates.




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114 Psyche [December
The material for this key has been modified from the works of many authors, notably Smith (1903). Headlee (1921). Dyar (1922, 1928), Dyar and Shannon (l%M), Matheson (1925, 1929), Bradley (19361, Edwards (1932). Johannsen (1903,1923,1934), Marshall (1938) and King, Bradley and McNeel (1939).
Mosquitoes are small two-winged insects belonging to the order Diptera, family Culicidse. The Culicidse are separated from all other Diptera by a characteristic wing venation which is outlined by Edwards (1932) as follows: Subcosta (Sc) long and reaching costa; radius 4-branched, Ra+a forked, Ri+3 simple, no cross vein connecting R, and En; media two branched ; cross veins r-m and m-cu both present; cubitua forked; anal vein long and reaching wing margin; axillary vein absent or very faint (Fig. 5). There is no other single character which separates the family from other Dip- tera. Other common family characters are (1) the small or rudimentary first antenna1 segment and the more or less en- larged second segment, (2) the completely divided pronoturn, the posterior divisions of which appear to form part of the pleurse. These characters, however, are not distinctive since they are shared by one or more families of Diptera. The larvse of the Culicidae are distinguished from all other dipterous larvae by the presence of a complete head capsule and of only one pair of functional spiracles situated dorsally on the eighth abdominal segment opening free to the surface (Fig. 19) or into an air tube or by the presence of a com- plete head capsule and air sacs in the thorax and seventh abdominal segment (Fig. 17) (Ckaoborus) . KEY TO SVBFA~ULIBS OF CL-LICIDAE
Adults
1. Antennal flagellum 14 segmented ; vein Sc ending above or before base of Rs (Fis. 5). Mouthparts short, wings without scales : ..Ì£,Ì£,Ì£_Ì£.Ì£--Ì -A3ixinse Antenna1 flagellum 13 segmented ; vein Sc ending much beyond base of Rs. Wings with scales at least on fringe ÌÔÌ£_ÌÔ-ÌÔ_.-Ì£. ...ÌÔ..ÌÔ.-̣̣...ÌÔÌÔ..-_ÌÔ 2 2. Mouthparts short, palpi incurved; scales almost con- fined to wing fringe: ̣̣..Ì£._..Ì£ -
Cbborinse
Mouthparts modified to form a long proboscis, palpi not incurved; wing veins and legs scaly: ____,--CWicwia?



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19391 Mosquitoes of Massachusetts 115
Larvae
1. Thorax narrow with distinct segmentation ; prolegs on the first 2 abdominal segments; tracheae ending in a pair of discs on eighth abdominal segment (Fig. . .
21) : --ÌÔ.--.--.-----..-.ÌÔÌÔÌ£ÌÔÌÔ.ÌÔ-ÌÔÌÔ.-ÌÔ Dzxznse Thorax distinctly broader than abdomen, without dis- tinct segmentation, paired prolegs lacking -.---------------- 2 Subfamily Dixinse
This group is represented by the single genus Dixa. KEY TO THE GEXCS DIXA
Adults
1. Tips of hind tibise noticeably enlarged, deep black, sharply contrasting with the remainder of the mem- ber; wing veins with clouded margins ; proboscis black, halteres yellowish, scutellum fuscous testa- ceous ; terminal clasper segment tapering, mesa1 pro- cess of the basal segment simple, elongate :---...clavata Tips of hind tibiae not so sharply differentiatedÌÔÌÔÌÔÌ 2. Petiole of Ra+s (measured on a straight line from its base to base of fork) less than % as long as Ro; pro- boscis, scutellum, and knob of the halteres yellow; crossvein of wing very feebly clouded, r-m crossvein slightly distad of the base of R4+5 : -------------- ----,., terna Wing with other characters ---ÌÔÌÔÌÔ-----Ì£.._...__.-Ì£ÌÔ...- 3 . .
3. Wing with one distinct spotÌÔÌÔÌÔÌÔÌÔÌÔ 4 Wing spot very indistinct or wanting .ÌÔ_.ÌÔÌÔÌÔ __5 4. Petiole of R2+3 and Rn subequal in length; proboscis and scutellum blackish : ----.--.--.._---,..........--..-.. centralis Petiole shorter ; proboscis and scutellum yellowish :-------- . notata
5. Dorsurn of the thorax as well as the upper part of the pleura black ; proboscis, halteres and scutellum dark : - - fzisca
Dorsum of the thorax yellowish with thoracic darker



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116 Psyche [December
stripes which may be more or less confluent; palpi dark ̣̣.__-_.ÌÔÌÔ..--Ì£ÌÔÌÔÌÔÌÔÌÔÌÔÌÔÌÔÌÔÌ 6 6.
First tarsal joint of fore leg about 2)$ as long as the . .
tibia : .__-.__-._ÌÔÌÔÌÔ---ÌÔÌÔ--ÌÔ---ÌÔ.-----ÌÔÌÔ cornuta First tarsal joint of fore leg about 3/4 as long as the . .
tibia ÌÔÌÔÌÔÌÔÌÔ---ÌÔÌÔÌÔÌÔÌÔÌÔÌÔÌÔÌÔ
7. Apical segment of the clasper of the male fully as broad beyond the middle as at the base; Sc ends about opposite the base of Rs; distance between the cross- veins measured on the media usually not exceeding v2 the length of the m-cu crossvein : _-.-----_-----_-_--- modesta Apical segment of the clasper of the male tapering ; Sc ends distinctly proximad of the base of Rs; distance between the crossveins about equal to the length . of .
the m-cu crossvein : --ÌÔ-_-ÌÔÌÔ---ÌÔ_--_--ÌÔ_-------Ì szmiizs Larvse
Only two of the species given in the key above are known in the larval stage, D. modesta Joh. and D. cornuta (Joh.) which may be separated by using the key by Johannsen (1934).
Subfamily Chaoborinae
KEY TO GENERA
Adults
Larvse
1. Eighth abdominal segment with an elongate single dor- sal respiratory siphon or air tubeÌ ÌÔÌÔÌÔÌÔ--ÌÔ_ ---2



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19391 Mosquitoes of Massachusetts 117
Eighth abdominal segment without an elongate single dorsal air tube; with a flattened spiracular disc on the eighth segment or with air sacs in the thorax and the seventh abdominal segment ............................ -.------3 Antennae inserted close together, folding outwardly and fitting into grooves on the head (Fig. 20) : .-------.------. ...................................................................... Corethrella Antennae inserted far apart, pendent in resting posi- tion (Fig 18) : ................................................ Mochlonyx Air sacs present in thorax and seventh abdominal seg- ment (Fig. 17) : ............................................ Chaoborus Air sacs absent, a well-developed spiracular disc on ........
eighth abdominal segment (Fig. 19) :
Eucorethra
KEY TO THE GENT'S CHAOBORL'S
Adults
Wings spotted or clouded- ................................................. 2 Wings without spots or cloudsÌÔÌÔÌÔÌÔÌÔÌÔÌ ----------- 4 Width of hind marginal wing fringe nearly as great as distance between cubitus and hind margin .ÌÔ--.ÌÔ.-_.Ì 3 Hind marginal wing fringe less than half the distance between cubitus and hind margin : trivittatus Femora and tibiae with numerous distinct spots : ............ punctipennis
Femora and tibiae without distinct spots except at bases and apices : .......................................................... albatus Mesonotum with dark longitudinal bands : -_ americanus Mesonotum with yellowish red longitudinal bands :.----..- ....................~......~.................................................. albipes Pre-labral leaf-like appendages very narrow and lan- ...................................................... ceolate : punctipennis
Pre-labral leaf-like appendages less than seven times as long as broad -..-.......ÌÔ..-...-...ÌÔÌÔ--...ÌÔ---Ì£._...---- __.__2 ......
Mandibular fan with 25 or more rays:
americanus
Mandibular fan with not over 18 rays- ..................-.... 3 Mandibular fan with 16-18 rays : ................ trivittatus Mandibular fan with not more than 12 rays :.---albipes Larva of C. albatus is unknown.




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118 Psyche [December
Adults
2. Scutellar set2 numerous, arranged in two or three ir- regular rows : ------..----- ---------------- -------------- karnerensis Scutellar setae sparse, arranged in a single row : ------------ - - fuliginosus
1. Clypeal and frontal spines barbed from base to a little beyond middle : -.Ì£-.Ì£.-..ÌỘ̣_...__--.ÌÔ-.Ì karnerensis These spines with long barbs beyond middle : .---cinctipes *
The larva of M. fuliginosus is unknown.
The following genera of the Chaoborinse are represented by single species: Corethrella brakeleyi Coquillett and Eu- corethra underwoodi Underwood.
Subfamily Culicinae
KEY TO GENERA
Adults
Postnotum with a median tuft of set2 located near the posterior margin (Fig. 2) : _.-.---ÌÔÌÔÌÔ-.--- Wyeomyia Postnotum without a tuft of set=- -ÌÔÌÔ-.----_.Ì£ÌÔ--- _-2 Wings with the second marginal cell not half as long as its petiole (Fig. 5) : .-----.------------ -------------- --,- Uranotsenia Wings with the second marginal cell more than half as long as its petiole ---ÌÔÌÔÌÔÌÔÌÔÌÔÌÔÌÔÌÔÌÔ.-- 3 Scutellum rounded or crescent-shaped with an even fringe of marginal set2 (Fig. 3) : ÌÔÌÔ---_.-_ÌÔAnophe Scutellum distinctly trilobed (Fig. 4) with marginal setse aggregated on the lobes ----_.----.-----__----. _ ..--.. __..-_-.--4 Spiracular bristles present (Fig. 2) _--ÌÔÌÔÌÔÌÔ.-----ÌÔÌ 5 Spiracular bristles absentÌÔÌÔÌÔÌ -------------- ---- ---6 Post-spiracular bristles present (Fig. 2) ; abdomen of female with the eighth segment wholly retractile :_----- Psorophora
Post-spiracular bristles absent; cross veins of wings



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19391 Mosquitoes of Massachusetts 119
tending to lie in line, or mesonotum with bare areas devoid of scales or both : ÌÔ.-ÌÔ..Ì£.ÌÔ---.-.. TheobaZdia 6. Pronotal bristles only two stout setae (Fig. 2) ; proboscis with black and white scales so arranged as to form longitudinal striae ; mesonotum with six longitudinal lines of white scales : ----Orthopodomyia Pronotal bristles more than two, generally a prominent row ; proboscis without longitudinal striae ; mesonotum without six longitudinal lines of white scales- ------------- 7 7. Wings with scales distinctly large and broad ; first joint of all tarsi with broad median rings; all of the other tarsal joints black with basal half white scaled :--.------- . . Mansonia
Wings with scales normal ; tarsi not as above- ----------------- 8 8. Post-spiracular bristles present; female usually with the abdomen pointed and the cerci exserted or tarsi with white rings on both ends of joints : ..---------- Aedes Post-spiracular bristles absent; female with a blunt ab- domen ; tarsi without white rings involving both ends . .
of joints : _Ì£._.ÌÔ--..__._.ÌÔ-ÌÔÌÔ_.ÌÔ----ÌÔÌ Culex Larvse
1. Eighth segment of abdomen provided with a distinct, elongate respiratory or air tube (Fig. 8) .Ì£_.---.ÌÔ_..ÌÔ- 2 Eighth segment of abdomen without a distinct, elongate respiratory or air tube (Fig. 9) : ._._.Ì£--ÌÔ.... Anopheles 2. Air tube without a pecten (Fig. 12) ,------------ ---------- ---- ---3 Air tube with a pecten (Fig. 8) ÌÔ.----,ÌÔÌÔÌÔÌÔÌÔ 5 3. Air tube about twice as long as wide, the apical por- tion sharply attenuated and provided with saw-like teeth dorsally for penetrating into plant tissues (Fig. 12) ; larva found attached to the roots of certain aquatic plants : ----------.--- -------------- ---- Mansonia Air tube about three times as long as wide, tapering more or less uniformly to the apex --.ÌÔ--..ÌÔ.Ì£--.-ÌÔ 4 4. Air tube with many short single hairs; larva found in the water of the pitcher plant : __.-._----.-.ÌÔ_.- Wyeomyia Air tube without scattered single hairs but with a large pair of hair tufts before the middle; abdomen



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120 Psyche [December
with dorsal chitinous plates on the sixth, seventh and eighth segments : ---ÌÔ--------------------..----- Orthopodomyia Head elongate, elliptical; head hairs single, stout like heavy spines : .............................................. Uranotsenia Head nearly circular or transverse; head hairs not like heavy spines ------------------------------------------------------------------ 6 Air tube with several pairs of ventral tufts : .---------Culex Air tube with a single pair of ventral tufts or with a single pair of tufts and a median ventral row of 10 to 12 unpaired tufts or without any paired ventral tufts ........................................................................... 7 Air tube with the paired hair tufts placed close to the base between the pecten rows : -------------------- Theo baldia Air tube with the paired hair tufts placed near or be- yond the middle ............................... ---- ---- ---- ---- ---- - ---- ------8 Anal segment ringed by the dorsal plate, with tufts of the ventral brush piercing the ring : ----------Psorophora Anal segment not ringed by the dorsal plate, or if ringed, the tufts of the ventral brush posterior to the ring :---- Aedes
KEY TO THE GEXUS AEDES
Adults
Proboscis of female ringed with white (Fig. 1) ------------- 2 Proboscis of female not ringed with whiteÌÔÌÔÌÔÌÔ ---- 3 Abdomen with a pale longitudinal dorsal stripe (Fig. 1) ; wings with black and white scales : -------------- sollicitans Abdomen without a pale longitudinal dorsal stripe ; wings with black scales : ----.-.---------.-.-.-- tasniorhynchus Tarsi with white rings on at least some of the segments (Fig. I) -------------------------------------------------------------------------- 4 . . . .
Tarsi without white rings ---ÌÔÌÔÌÔÌÔ---------ÌÔ----------ÌÔ-- White tarsal rings involving both ends of segments-------5 White tarsal rings basal only ---- ........................... 7 Wings scales markedly bicolored : ---- ----.. dorsaUs Wings scales uniformly dark, or nearly so- --------_------------ 6 Mesonotum uniformly reddish brown, or nearly so :-------- canadensis
Mesonotum pale with a broad dark medium stripe; ab- domen rather bluntly rounded : .................... atropalpus



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19391 Mosquitoes of Massachusetts 121
7. Tarsi with pale broad rings especially on hind legs; wings scales bicolored ÌÔ-ÌÔÌÔ. L ÌÔÌÔ---ÌÔÌÔÌÔÌÔ 8 Tarsi with narrow rings; wing scales uniformly dark or nearly so .... __ .---. _.__.._.__..___ -._._...... ____ _._. _.._..._.__.._-______-. 10 8. Lower mesepimeral bristles absent : .._----.-.------ excrucians Lower mesepimeral bristles present (Fig. 2) -..------------- __9 9. With three to five lower mesepimeral bristles; mesono- turn bronzy-brown on the disc, the scales on the ante- scutellar space, lateral margins and a sub-dorsal line each side of the disc whitish : ---ÌÔÌÔ--ÌÔ.-._-___. stimulans With two lower mesepimeral bristles; mesonotum with a broad median stripe of yellowish brown scales, the anterior edge, the sides of the disc and antescutel- lar space with yellowish white to white scales :,,..jitchii 10. Last two abdominal segments nearly entirely white scaled, venter entirely yellowish white : __.__Ì£_ cantator Last two abdominal segments with apical and basal bands ; venter with each segment with a median black spot or stripe which may be joined to lateral black spots forming a Y : ._.__.._ ...-. _.._..-_._._..._.___.-__.__- ..-- _vexans Lower mesepimeral bristles absent- --------------------.----- - ---- 12 Lower mesepimeral bristles present -.--.,----.--- ÌÔÌÔÌÔÌÔ . .
Mesonotum with silvery scales- ---.ÌÔ-ÌÔÌÔ.--ÌÔÌÔÌ 13 Mesonotum without silvery scales ---- ÌÔÌÔÌÔÌÔÌÔÌÔÌÔ Mesonotum silvery on the sides with a dark brown median stripe which widens behind the middle and which is divided by the antescutellar space, the ante- scutellar space is margined by silvery scales : -------------- . . triseriatus
Mesonotum with a medium silvery stripe reaching scu- tellum or entirely silveredÌÔÌÔ ---- ÌÔÌÔÌÔÌ --.-------- 14 14. Mesonotum with a broad well-defined median silvery stripe : ---.--.----.ÌÔ--._--.._-_-.....--..--..ÌÔ---..----.....,-- attanticus Mesonotum with a narrower poorly defined or diffuse median stripe ; mesonotum of male entirely silvery ; a very small blackish species : ---.ÌÔ--ÌÔ.-ÌÔ_ÌÔÌÔ dupreei 15. Abdomen with a continuous lateral white line; mesono- turn uniformly colored with golden-brown scales, paler about the antescutellar space : -_-.ÌÔ._--ÌÔ_-________ cinereus Abdomen without a continuous lateral white line; me-



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122 Psyche [December
sonotum with a median dark band .-----ÌÔ---.--ÌÔ.--Ì 16 16.
Mesonotum with two yellow or yellowish-white stripes separated by a narrow, dark brown median band; sides dark brown to black : -.----_.-..----ÌÔ.--..-_ trivittatus Mesonotum with the golden brown median stripe slightly constricted at the middle; with two short sublateral stripes posteriorly : _-ÌÔ..--..--.....ÌÔÌÔ--..----Ì hirsuteron Mesonotum with the median band widening posteriorly ; apical margins of abdominal segments with fine long brownish hairs : ÌÔ-..Ì£..-ÌÔÌÔ._.ÌÔÌ£-...ÌÔ_.. aurif er 17. With one to three small mesepimeral bristles ; mesono- turn with brownish-yellow scales uniformly distrib- uted : _ÌÔ_..-ÌÔ---ÌÔÌÔÌÔÌÔÌÔÌÔ.--ÌÔÌÔÌÔ..-. intrudens With three or more stout mesepimeral bristles ; mesono- turn with a median stripe or paired brown median lines ÌÔÌÔ-.--ÌÔÌÔÌÔÌÔÌÔÌÔÌÔÌÔÌÔÌÔ..-.--ÌÔÌÔÌÔ.--ÌÔ 18 18. Mesonotum with paired brown median lines- ---.-..-------- 19 Mesonotum with a median brown stripe- -----..-ÌÔ..---ÌÔ 20 19. Mesonotum yellow or bronzy with a pair of black median lines, often joined into a median stripe; legs deep black : ......ÌÔÌÔ,ÌÔÌÔÌÔÌÔ.--.-...-ÌÔÌÔÌÔ diantseus Mesonotum with paired median lines separated . by . a broad golden brown line : -.--ÌÔ--~...ÌÔ.-.ÌÔÌÔ....- zmp~ger Mesonotum with paired median lines separated by a narrow yellow line ; sides grayish : ............., communis 20. Mesonotum with the median band laterally expanded near the middle : -ÌÔ.-ÌÔ...--ÌÔ,-ÌÔ..-.ÌÔÌÔÌ trichurus Mesonotum with the median band only slightly darker than the lateral margins : .__....-.-.ÌÔ.-.---- pzmctor* . . ~ implaca bilis
*
*There are no satisfactory characters with which to separate these species. In A. punctor the median band of the mesonotum may in some cases have a middle line of slightly paler scales. The last abdominal segment of A. implacabilis is usually pale scaled whereas in punctor it has a V-shaped dark area.
Larvse




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19391 Mosquitoes of Massachusetts 123
Air tube with several dorsal hair tufts, anal gills nor- mal : ------------- ---- ÌÔÌÔÌÔÌÔÌÔÌÔ ---- ---- ------- trichurus Air tube without several dorsal hair tufts, anal gills large and inflated : -.-ÌÔÌÔÌÔ-ÌÔÌÔÌÔ atropalpus Pecten with detached teeth outwardly (Fig. 15) ------------ 4 Pecten without detached teeth outwardly (Fig. 16) ----9 Antennae enlarged basally : .._--ÌÔÌÔÌÔÌÔÌÔÌÔ.-.--.- aurif er Antennae not enlarged basally ----ÌÔ.ÌÔÌÔÌÔÌ Antennae as long as head : _._.ÌÔ.ÌÔÌÔ---ÌÔÌÔ----.--- diantzus Antennae not as long as head ---- --------- -----------------6 Both pairs of head hairs (Fig. 8) double : --.--. excrucians Both pairs of head hairs not double ÌÔÌÔÌÔÌÔÌÔÌÔÌÔ 7 Lateral abdominal hairs (Fig. 8) single beyond second segment Ì£ÌÔÌÔ---ÌÔ-ÌÔÌÔ.-ÌÔÌÔÌ ------.------ ------------ 8 Lateral abdominal hairs not single beyond second seg- ment : .Ì£.---_--..-ÌÔ..ÌÔ-_-_ÌÔÌÔÌÔ__-ÌÔÌÔÌ vexans Air tube 2% to 3 times as long as wide, tuft on air tube large : ._._---̣̣ÌÔ.-_-.--..--..Ì£ÌÔ-- intrudens Air tube 3% to 4 times as long as wide, tuft on air tube small, located on outer third of tube : ----..----,--, cinereus Comb scales in a single or in an irregular single rowÌÔ-1 Comb scales in a triangleÌÔÌÔÌÔ -------------- -------------- ------ 13 Anal segment ringed by plateÌÔÌÔÌÔÌÔÌÔÌÔÌÔ ------ 11 Anal segment not ringed by plate : -------------.---, triseriatus Air tube five times as long as wide : .---.--.-------,--,--- dupreei Air tube 2 to 3y2 times as long as wide- --ÌÔÌÔÌÔ... 12 Dorsal brush of anal segment consisting of two pairs . .
of long hairs : -----------.--.- ---- ----.,.........-.....- implacabths Dorsal brush of anal segment consisting of a pair of long hairs and a pair of dorsal tufts : -----._.-.-. atlanticus Anal segment ringed by plate ------ ÌÔÌÔÌÔÌÔÌÔÌÔ -------- 14 Anal segment not ringed by plateÌÔÌÔÌÔÌÔÌÔÌÔÌÔÌÔ Upper and lower head hairs double : -.ÌÔ_.--....ÌÔ. punctor Upper and lower head hairs single --ÌÔÌÔÌÔÌÔ..--.--___--Ì 15 Anal gills at least as long as anal segment :---.trivittatus Anal gills shorter than anal segment ----- -------- 16 Lateral abdominal hairs double on segments two to five; scale of comb with a stout apical spine : -..-.... sollicitans



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