G. S. Tulloch.
A Key to the Mosquitoes of Massachusetts.
Psyche 47:113-136, 1940.

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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 Tulloch (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. 1 Grateful acknowledgment is made to the following for assistance: Dr. R. F. Feemster, Director, Division of Communicable Diseases, Massachusetts Department of Public Health; Dr. V. A. Getting, Tech- nical Director. Massachusetts Mosauito Survev: Prof. J. C. Beauaert. Consulting ~ntomologist; V. A. ~elc R. P. ~oldkkorth, Jr., C. E. ~lliott; 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, l928), Dyar and Shannon (1%4), Matheson (1925, l929), Bradley (1936), Edwards (1932), Johannsea (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, Rz+-3 forked, R4+s simple, no cross vein connecting R, and Rn; media two branched ; cross veins r-m and m-cu both present; cubitus 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 pleurae. These characters, however, are not distinctive since they are shared by one or more families of Diptera. The larvae of the Culicidaa 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) (Chaobonts). .
TO SI~WAMILIE,~ OF CLXICIDAE
Adults
1. Antennal flagellum 14 segmented ; vein Sc ending above or before base of Rs (Fig. 5). Mouthparts short, wings without scales : Ì£.̣̣̣...Ì£....-ÌÔ_... Dixins3 Antennal flagellum IS segmented ; vein Sc ending much beyond base of Rs. Wings with scales at least on fringe -..-.ÌÔ.-L.--ÌÔ_..ÌÔ. .ÌÔ-_ÌÔÌÔ..-..ÌÔ..ÌÔÌÔ. 2 2. Mouthparts short, palpi incurved; scales almost con- fined to wing fringe : Ì£._.-.---_Ì£-Ì£_..Ì Chao bodnss Mouthparts modified to form a long proboscis, palpi not incurved ; wing veins and legs scaly: CuJicinse



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19391 Mosquitoes of Massachusetts 115
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. .
2 1 ) : _.-..--ÌÔ_--._-._-...-ÌÔ__.ÌÔÌÔ ÌÔÌÔ--. -.ÌÔ__.~----_._ Dzxznz Thorax distinctly broader than abdomen, without dis- tinct segmentation, paired prolegs lacking- ._---...--.. __.__2 2. Antennae prehensile, with long and strong apical spines, (Fig. 17) : ....___ÌÔ_.-__._.._._.-ÌÔÌÔ.ÌÔ-.___...____ ..Chaoboring3 Antennae not prehensile (Fig. 8) : _._-.__-ÌÔ.__----. Culicinz Subfamily Dixinse
This group is represented by the single genus Dixa. 1. Tips of hind tibiae 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 :--.-.Aavata Tips of hind tibiae not so sharply differentiated ,-.-_-..-..... 2 2. Petiole of Ra+3 (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 :ÌÔÌÔ.-_..ÌÔ......,.te Wing with other characters- _.-_ÌÔÌÔ.--.._____Ì£__ __ ..-_ _--___3 . .
3. Wing with one distinct spot ~ÌÔ_._-._______~.-ÌÔ.._...-ÌÔ--._.~ÌÔ 4 Wing spot very indistinct or wanting_.___ ..-.........-...... _...__ 5 4. Petiole of R2+3 and R:, subequal in length; proboscis and scutellum blackish : ÌÔÌÔ_..-._______-..._-_----... centralis Petiole shorter ; proboscis and scutellum yellowish :-------- _ _ _ _ _ _ _ _ _ _ _ _ _ notata
5. Dorsum of the thorax as well as the upper part of the pleura black ; proboscis, halteres and scutellum dark : _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ fusca 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 -----------------------------------------.----------------------_.----.-------- 6 6. First tarsal joint of fore leg about % as long as the . .
tibia : ÌÔ_--__--ÌÔ--------ÌÔÌÔ-ÌÔÌÔÌÔÌÔÌÔÌÔÌÔ_--_ cornuta First tarsal joint of fore leg about % as long as the . .
tibia _-_.-----_-----------------ÌÔ--------Ì£---ÌÔÌÔ--ÌÔ-------_-_.-_-_ 7 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 1/9 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---ÌÔÌÔ-- -----_-_------ szmz7zs 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 (l934).
Subfamily Chaoborinae
KEY TO GENERA
Adults
Larvse
1. Eighth abdominal segment with an elongate single dor- sal respiratory siphon or air tube ---- _ --.----. __ ----- -_.___.-_---2



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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) : -_-_ÌÔ---ÌÔÌÔ--ÌÔÌÔÌÔÌÔÌÔÌÔ- 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 CHAOBORTJS
Adults
Wings spotted or clouded ---- ÌÔÌÔÌÔÌÔÌÔÌÔÌÔ---ÌÔÌÔ-- Wings without spots or clouds ------- ---------- ---- - ----------------- ---4 Width of hind marginal wing fringe nearly as great as distance between cubitus and hind margin --ÌÔ..__..__.Ì£Ì 3 Hind marginal wing fringe less than half the distance between cubitus and hind margin : ___--Ì£_ÌÔ. trivittatus Femora and tibiae with numerous distinct spots : ------------ punctipennis
Femora and tibiae without distinct spots except at bases and apices : -_-_._.__Ì£__Ì£____-.ÌÔÌÔÌÔÌÔ-_ÌÔÌÔ_--_-____ albatus Mesonotum with dark longitudinal bands : -. americanus Mesonotum with yellowish red longitudinal bands :-------- - albipes
Pre-labral leaf-like appendages very narrow and lan- ceolate : ----__-ÌÔÌÔÌÔÌÔÌÔÌÔÌÔÌÔÌ punctwennis Pre-labral leaf-like appendages less than seven times as long as broad __--...ÌÔ.A..__-ÌÔÌ£_ÌÔÌÔ_ÌÔ.___-.__.._ _-_.-.__ 2 Mandibular fan with 25 or more rays:------americanw Mandibular fan with not over 18 rays ÌÔÌÔÌÔÌÔÌÔ 3 Mandibular fan with 16-18 rays : ---------------- trwittatus Mandibular fan with not more than 12 rays :----albi'pes Larva of C. albatus is unknown.




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Psyche
[December
KEY TO THE GENCS A~OCHLOXYX
Adults
Wing vestiture entirely pale yellow --ÌÔ.-.--ÌÔ.ÌÔ-.ÌÔÌÔ-. 2 Wing vestiture black and yellow : ..------.---.------.- cinctipes Scutellar setae numerous, arranged in two or three ir- regular rows : _...-ÌÔÌÔÌÔ.--.--ÌÔ--ÌÔÌÔ.--ÌÔ-- karnerensis Scutellar setae sparse, arranged in a single row: -.---------- . . . f uliginosus
Larvz*
Clypeal and frontal spines barbed from base to a little beyond middle : -.--Ì£_.---ÌÔÌÔÌÔÌÔÌÔ 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 bmkeleyi Coquillett and Eu- corethra underwoodi Underwood.
Subfamily Culicinae
I~:Y TO GEXEEA
Adults
Postnotum with a median tuft of setae located near the posterior margin (Fig. 2) : --_..--ÌÔ-.-ÌÔ_Ì£-Ì£ Wyeomyia Postnotum without a tuft of setae .....--.--ÌÔ.-Ì£-....ÌÔÌÔÌÔ-- 2 Wings with the second marginal cell not half as long as its petiole (Fig. 5) : Ì£--._.Ì£..-_ÌÔ..__-ÌÔ--Ì Uranotsenia Wings with the second marginal cell more than half as long as its petiole -ÌÔ.__.--ÌÔÌÔ.ÌÔÌÔÌÔ.--------ÌÔ---ÌÔÌÔ-- 3 Scutellum rounded or crescent-shaped with an even fringe of marginal set= (Fig. 3) : -------.---.--..Anopheles Scutellum distinctly trilobed (Fig. 4) with marginal set= aggregated on the lobes ---- .ÌÔ.__.__.-.-.-Ì£ÌÔ--.Ì 4 Spiracular bristles present (Fig. 2) ----___.Ì£--ÌÔÌÔ.-..ÌÔ. 5 Spiracular bristles absentÌÔÌÔÌÔÌ --ÌÔ.Ì£ÌÔÌ£ÌÔÌÔ 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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Mosquitoes of Massachusetts 119
tending to lie in line, or mesonotum with bare areas devoid of scales or both : --ÌÔ_--.._---___.-_-.--.--- Theobaldia 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 : _._...._----..-._---...--... Orthopodornyia Pronotal bristles more than two, generally a prominent row ; proboscis without longitudinal striae ; mesonotum without six longitudinal lines of white scales -------------_ 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 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.-..-...-.-.--.---.--ÌÔÌÔÌÔ_--ÌÔ-------- Culex Eighth segment of abdomen provided with a distinct, elongate respiratory or air tube (Fig. 8) ....----Ì£ÌÔ--.- -2 Eighth segment of abdomen without a distinct, elongate respiratory or air tube (Fig. 9) : .__.___--_-._-_--. Anopheles Air tube without a pecten (Fig. 12) Ì£ÌÔÌÔ----._ÌÔÌÔ- 3 Air tube with a pecten (Fig. 8) ---.---_- - ---- ---------- -------------- 5 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 : -._.~__~..._._-.Ì£_.--ÌÔÌÔ-~~.-~ÌÔ.---- Mansonia Air tube about three times as long as wide, tapering more or less uniformly to the apex.__ ..--ÌÔ---_Ì£_-..--.-ÌÔ-- 4 Air tube with many short single hairs; larva found in the water of the pitcher plant : --..---------------- 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 : --------------------------.-,---.- Orthopodomyia Head elongate, elliptical; head hairs single, stout like heavy spines : Uranotasnia
Head nearly circular or transverse; head hairs not like heavy spines ÌÔÌÔÌÔÌÔ-ÌÔÌÔÌÔÌÔ---ÌÔ-ÌÔÌÔÌÔÌÔ------ 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 : .................... Theobaldia Air tube with the paired hair tufts placed near or be- yond the middle -------------- ----- ---ÌÔ---------------ÌÔÌÔ------ÌÔ------ 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 GENFS AEDES
Adults
Proboscis of female ringed with white (Fig. 1) 2
Proboscis of female not ringed with whiteÌÔÌÔÌÔÌÔ 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 : ----Ì£----------ÌÔ- tasniorhynchus Tarsi with white rings on at least some of the segments (Fig. 1) --------------------------------------------------------------------------4 s . . .
Tarsi without white rings ------- ---- ------------------- ---------------- 11 White tarsal rings involving both ends of segments-----5 White tarsal rings basal only ............................................ 7 Wings scales markedly bicolored : -----------.------------ dorsalis Wings scales uniformly dark, or nearly
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
Tarsi with pale broad rings especially on hind legs; wings scales bicoloredÌÔÌ ---- ------ÌÔÌÔÌÔ---ÌÔ--- ---- ---8 Tarsi with narrow rings; wing scales uniformly dark or nearly so ---- ------------- -------------------------------_-----------------.- 10 Lower mesepimeral bristles absent : -.-------------- excrucians Lower mesepimeral bristles present (Fig. 2) -----------------, 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 : -----_--------.--------. 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 :-.--fitchii Last two abdominal segments nearly entirely white scaled, venter entirely yellowish white : _---------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 : -~--.-_.---ÌÔ---_---._----.-.------....-...... vexans Lower mesepimeral bristles absentÌÔÌÔÌÔÌ --------------- 12 Lower mesepimeral bristles present ------------- ---------- ---- ---I7 . .
Mesonotum with silvery scales- ---.-----_-ÌÔÌÔÌÔÌÔÌÔÌÔ-- 13 Mesonotum without silvery ~cales---~--~--~-------------~--~-----15 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 silvered- --------------.---------------------------- 14 Mesonotum with a broad well-defined median silvery stripe : ÌÔ.-_-_--.-ÌÔ.------_----.------__-ÌÔ--_---_ÌÔ-------- atlanticus Mesonotum with a narrower poorly defined or diffuse median stripe ; mesonotum of male entirely silvery ; a very small blackish species : ----------------------------. dupreei Abdomen with a continuous lateral white line; mesono- turn uniformly colored with golden-brown scales, paler about the antescutellar space : ----------------..--.---.. cinereus Abdomen without a continuous lateral white line; me-



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122 Psyche [December
sonotum with a median dark band- --_.ÌÔ.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 : ÌÔÌÔ..ÌÔÌÔÌÔ..-. trimttatus Mesonotum with the golden brown median stripe slightly constricted at the middle; with two short sublateral stripes posteriorly : --.-......~..-ÌÔ.---ÌÔÌÔÌÔ,...,, Mrsuteron Mesonotum with the median band widening posteriorly ; apical margins of abdominal segments with fine long brownish hairs : --..--ÌÔÌÔ-..-.--ÌÔ--ÌÔÌÔ.ÌÔÌÔ-Ì aurif er 17. With one to three small mesepimeral bristles; mesono- turn with brownish-yellow scales uniformly distrib- uted : -ÌÔ--_-ÌÔ.ÌÔÌÔÌÔÌÔÌÔÌÔÌÔÌÔÌÔ intrudens With three or more stout mesepimeral bristles ; mesono- turn with a median stripe or paired brown median lines ----.-- ---- ÌÔÌÔ--.ÌÔÌÔÌÔÌÔ---ÌÔÌÔÌ ----------.-- 18 18. Mesonotum with paired brown median lines- ------------..- 19 Mesonotum with a median brown stripe- --------.-.----------.- 20 19. Mesonotum yellow or bronzy with a pair of black median lines, often joined into a median stripe; legs deep black : Ì£..._--.._......._..-.--ÌÔ..ÌÔ-..ÌÔ-Ì£ÌÔÌÔÌ£ diantseus Mesonotum with paired median lines separated by a 0 .
broad golden brown line : ÌÔ---ÌÔÌÔ---ÌÔÌÔ.--.-. zmpzger Mesonotum with paired median lines separated by a narrow yellow line ; sides grayish : -.-......-.... communis *There are no satisfactory characters with which to separate these species. In A. wtor 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
1. Air tube with tuft within pecten ÌÔ-.....Ì£_Ì£...__-Ì£..--Ì£Ì 2 Air tube with tuft beyond peeten--_ ÌÔÌÔ--.ÌÔ.---.-ÌÔ.- 3



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19391 Mosquitoes of Massachusetts 123




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124 Psyche [December
Lateral abdominal hairs triple on segments three to five ; scale of comb with a fringe of spines of approximately equal length : ------.----------------_------------.----- t~niorhynchus Air tube at least four times as long as wide : ---------.fitchii Air tube three times or less as long as wide ------------------ 18 . .
Head hairs single
-------- ---- .................... -------------- 19 Head hairs double or multiple
21
Anal gills at least as long as anal segrnent---------------------.20 Anal gills much shorter than anal segment: -----.dorsalis Scale of comb with broad apex bearing four to seven stout spines : ------------- ---- ------- ............................ communis Scale of comb with single stout spine : ---.--,----.---- impiger Both pairs of dorsal head hairs multiple- 22 Both pairs of dorsal head hairs not multiple- --.--.-----.-. 23 Anal gills budlike ; found in salt water : ------------ cantator Anal gills well developed : ------------_-----..---.-------- canadensis Lower head hairs double, upper triple :-----,--hirsuteron Lower head hairs single, upper double : -----,-----. stimulans KEY TO THE GEI^US THEOBALDIA
Adults
Tarsi with poorly defined yellowish white rings at both ends of some of the joints : --------,.....----.--------, morsitans Tarsi without rings on any of the jointsÌÔÌÔÌÔÌ 2 Scales of the wings mixed, black or brown and white especially along the costal margin; proboscis with intermixed black and white scales : ------------_--- inornata Scales of the wings all brown or blackÌÔ- ----.--.- _ .--_--.-- -- ---. 3 Mesonotum brown marked with yellowish lines or spots ; wings with some of the scales slightly aggregated along the third vein ; a large species : -------- impatiens Mesonotum entirely reddish brown ; wing scales normal ; each abdominal segment with an apical row of coarse yellow hairs ; a small species (4 mm.) : -------. mdanum Larvas
Pecten produced into long hairs on outer half (Fig. 13) --------,---------------------------------------------------------------------------------- 2 Pecten not produced into long hairs on outer halfÌÔ----.