Term Definition
Abdomen The 9 body segments lying posterior to the three thoracic segments.
Accessory Blade A thin, flat appendage of blade, usually on apex of basal antennal segment, joined with blade at base.
anal In the direction or position of the anus, near the anus or on the last abdominal segment; towards the posterior.
Anal setae Setae mounted apically on the procercus.
Anal tubule 1-3 (usually 2) pairs of mostly oblong (but also ovoid, tapering, etc.) appendages of the anal segment above and between posterior parapods.
annulate Comprised of ring(s).
Antennal pedestal Base or platform on which antenna is located.
Antennal Ratio (AR) (of larva) the ratio of the 1st antennal segment to the combined lengths of the distal ones (the flagellum).
anterior At or towards the front.
apical At or towards the apex (tip).
Apotome Dorsal sclerite of head.
basal At or towards point of attachment or main body.
biarticulate Two-jointed, as in SIV bisensilla.
bifid Cleft or divided into two parts; forked.
Blade Any thin, flat structure like a leaf or a sword or knife; an elongate, flattened, usually stiff spicule; specifically the structure located generally on the apex or subapex of the basal antennal segment.
B seta Of maxillary palp: basal lamellate and apically attenuate, or laceolate to bristle-like seta on apical surface of maxillary palp near bisensillum.
cephalic Pertaining to the head
Cephalic setae Dorsal and lateral setae of head capsule, numbered with arabic numerals starting from labral sclerite setae.
Chaetae A thin, elongate outgrowth of the cuticle, specifically on the labrum with 2-11 (usually 6-9) pairs of non-sensitive, non-articulated, simple or mostly mesally serrated, occasionally bilaterally serrated blades to each side of setae anteriores.
Claw Any hooked structure, specifically the sclerotized structures on the apices of anterior and posterior parapods.
Clypeus Part of the insect head to which the labrum is attached anteriorly; specifically a dorsal apotome that may be delimited from the frontal apotome, anterior to the clypeus (all, some or none of these may be delimited).
composite Compound, as in median mentum.
crenulate Having the margin with small rounded teeth.
distal Further from the body.
dorsal On the upper surface.
Dorsal Pit A sensory pit located on the latero-median region of the dorsal head.
Dorsal Tooth On the mandible, a tooth that lies dorsal to the eclosion line near the midpoint of the head.
Dorsomentum Dorsal wall of double-walled mentum.
Epipharynx Anteriormost part of labrum bordered by labral margin, ungula and basal sclerite.
Fenestra A window; a transparent glassy spot or mark; specifically an area of thinned cuticle on the anterior frontal apotome, lying slightly posterior to the cephalic setae SIII.
Flagellum The apical antenna; more generally, any whip or whip-like structure.
Frons The single medio-anterior sclerite of the insect head, usually lying between the epicranium and the clypeus.
Frontal apotome The most dorsal sclerite of the head carrying frontal setae, delimited anteriorly from the clypeus.
Fronto-clypeal apotome The fused clypeus and frontal apotome.
Gena (pl. genae) Sclerite on each side of head making up larger portion of head capsule (except frontal apotome and postmentum), meeting dorsally at coronal suture when frontal apotome not reaching postoccipital margin.
Gula Throat sclerite extending from submentum to posterior margin, i.e. sclerite posterior to posterior tentorial pits; laterally bounded by genae.
Hypopharynx Median lobe of the preoral cavity of the mouthparts.
Labral brush A brush of chaetae on the anterior palatum.
Labral lamella One to several, smooth to pectinate lamellae (or teeth) between setae anteriores on labrum and tormal bar.
Labral sclerites Sclerites on dorsal side of labrum carrying labral setae (SI and SII); apparently lacking in Aphroteniinae, may be fused with clypeus to form a clypeolabrum, with both clypeus and frontal apotome to form a frontoclypeolabral apotome consist of a single sclerite or divided into two central, unpaired sclerites and 1-3 pairs of lateral sclerites.
Labral setae Cephalic setae (SI and SII), situated on labral sclerites or corresponding areas.
Labrum (adj. labral). The 'upper lip', forming the roof of the preoral cavity and mouth; derived from the first head segment, specifically the anteriormost sclerite of the head bordered anteriorly by the tormal bar.
lamelliform Made up of or resembling leaves, blades or lamellae.
lateral At, or close to, or towards the side.
Lateral tubules Small tubule laterally on each side of segment X in some Chironomini.
Lauterborn organ pedicel A stalk or stem supporting the Lauterborn organs.
Lauterborn organs Compound organ generally at apex of second antennal segment, consisting of a peg sensillum and 2 series of digitiform, thin-walled extensions; may be opposite (usually) or alternate (rarely) or present apparently on different segment than 2nd.
Ligula The glossae plus paraglossae of the prementum of the labium, whether fused or separate.
Mandible (adj. mandibular). The jaws, paired, usually toothed, structures inserted laterally, dorsal to the maxillae.
Mandibulae basal striae
M-Appendage Medio-ventral appendage of prementum which may be reduced to fine teeth (as in several Diamesini), very large and pronounced with several serrations, smaller with only median and paramedian lamellae relatively distinct (as in most Orthocladiinae and Chironominae), or consisting of a triangular plate with lateral vesicles carrying a pseudoradula and apparently belonging to ventromentum (in Tanypodinae).
Maxilla (pl. maxillae) The second pair of jaws, jaw-like in chewing insects, variously modified in others; derived from the 5th head segment.
medial At or towards the middle.
median at the middle (midline), e.g. median mentum.
Mentum The ventral, fused, usually toothed plate derived from the labium.
Mola Area of inner margin of mandible between seta subdentalis and seta interna, often weakly sclerotized, sometimes spinose.
palmate Like the palm of a hand, with fingerlike processes.
Palpiger Part of maxilla carrying maxillary palp.
Palp (palpus; pl. palpi) An often finger-like, usually segmented appendage of the maxilla (maxillary palp).
Paraligula Curved scales, small sclerotized rods, deeply serrated plates, single pointed or serrated scales at each side of ligula at ventral apex of prementum.
Parapod Fleshy, unjointed, ventral protuberances on prothorax (anterior parapods) and last abdominal segment (posterior parapods) nearly always carrying apical claws.
Pecten A comb-like structure, as in pecten hypopharyngis on hypopharynx of Tanypodinae.
Pecten ephipharyngis Usually three median scales, lamellae, spines, or rods directly behind labral margin (tormal bar), being smooth or apically pectinate or serrate.
pecten hypopharyngis
Pecten mandibularis Comb of mostly stiff, straight setae often present on distal mesal side of mandible in Chironominae.
Pedestal A projecting, supporting structure, especially for antenna or Lauterborn organs in Tanytarsiini.
plumose Feather-like.
posterior At or towards the rear.
Post-occipital margin Extreme posterior, often sclerotized, rim of head capsule.
Precercal elaboration
Premandible A pair of ventral appendage-like structures on labrum, taking the form of toothed plates or processes.
Premandibular brush Brush of microtrichia sometimes present on mesal margin of premandible.
Premento-hypopharyngeal complex Soft double-lobed structure dorsal of, and to a large extent covered by, mentum in ventral view, and posterior and opposed to labrum. Consists of prementum and hypopharynx.
pro- Designating the first of a series of structures such as thorax.
Procercal seta
Procercus (pl. procerci) Preanal tubercle, carrying 1-20 apical setae (procercal setae) and usually 2 lateral setae, rarely absent; may carry procercal spurs.
proximal Nearer to body.
Pseudoradula In larval Tanypodinae, excl. Tanypus, longitudinal band of minute spinules on dorsal side of M-Appendage.
retractable antenna
retractile (As of antenna in Tanypodinae), capable of retraction into the head capsule.
Ring organ Campaniform sensillum present on basal antennal segment, at base of mandible, and on ventrobasal sclerite of maxillary palpus.
Scar Characteristic delineated spot, usually representing the site of a seta that is lost.
sclerite Any plate of the body wall bounded by membrane or sutures.
Sensillum A simple sense organ, as in SIV and Sensillum minusculum.
Sensillum minisculum Tiny sensillum ventrolaterally on mandible just lateral to long external seta near angle of convex edge.
serrate Saw-like, i.e., with notched edges like the teeth of a saw.
Seta intera (of mandible) Seta on inner dorsomedial seta of mandible with 3-40 usually pectinate branches.
Seta (pl. setae) A cuticular extension, a trichoid sensillum.
Seta subdentalis Bristlelike, peglike, lanceolate or scalelike, filiform, or pectinate seta ventrally on inner margin of mandible below mandibular teeth.
Seta submenti [SSm] Simple, bifid, branched or plumose pair of setae immediately posterior to mentum, anteriorly on submentum.
SIII (setae minuscula) Pair of small to minute hair-like sensilla chaetica usually between and slightly above SII on labrum.
SII (seta posteriores) Sensilla chaetica above and slightly lateral of SI on labrum.
simple Undivided.
SI (seta anteriores) Sensilla chaetica mesally on labrum above sclerotized labral margin.
SIV A (labrum sensillum) Larger, more prominent and mesal peg of bisensillum SIV, occasionally pointed and on tubercle thus apparently 3-“segmented”.
SIV B Smaller, less prominent and lateral peg of bisensillum SIV, occasionally on a common tubercle with SIV A.
SIV (bisensillum of labrum) Two pairs of short, thick-walled pegs or sensilla basiconica to each side of and above SII and SIII.
Spinulae Slender cuticular outgrowths lacking innervations; usually 2-6 sclerotized, mostly pointed scales in each lateral corner of membranous labral area, situated just mesad of triangular sclerite.
Spiracle An external opening of the tracheal system: in Chironomidae evident only in few Podonominae, on the penultimate segment.
Spur An articulated spine.
star chart (a frivolous name for) the constellation-like arrangements of certain setae and sensory pits on the larval head, comprising ventrally the setae S9, S10 and SSm and the ventral pit (VP), dorsally the setae S5, S7 and S8 and the dorsal pit (DP) if present. Especially valuable in identification of Tanypodinae.
Stria (pl. striae) fine longitudinal impressed line(s), specifically ridges and/or furrows of the striate ventromental plate of most Chironominae, and mandibular striae in Chironomus.
Style Apical or slightly subapical peg- to bladelike non-articulated process on second antennal segment.
sub- Under, slightly less than or not quite so.
subqadrate Nearly square.
Swim setae Broad (taeniate, q.v.) setae, arranged along the lateral margin of the body, especially in certain Tanypodinae.
taeniae (adj. taeniate) Broadened setae as in swim setae (q.v.)
terminal Situated at the tip or extremity.
Thorax (adj. thoracic) The anterior 3 body segments, lying immediately posterior to the head, comprising pro-, meso- and meta-thoracic
Tormal Bar Sclerotized medial part of labral margin consisting of mesal arms of tormae fused with secondary sclerotizations of labral margin (labralia) to transverse bar.
trifid Cleft in 3.
Tubercle A small knoblike or rounded protuberance.
Ungula U-shaped sclerite surrounding epipharyngeal area laterally, carrying basal sclerite posteriorly, anterior opening closed by tormal bar, chaetulae basales usually attached on lower, inner, posteriolateral margins.
ventral Towards or at the lower surface.
Ventral Pit [VP] A sensory pit located on the genae of the ventral surface of the head.
Ventral tubules One to two pairs of tubules ventrally on 11th abdominal segment, probably at least originally acting as respiratory gills.
Ventrobasal spine A spine located ventrobasally on the posterior parapod in Corynoneura and Thienemanniella.
Ventromental beard Setae on dorsal, inner surface of ventromental plate.
Ventromental plate Lateral parts of ventromentum which may have internal striae in Chironominae.
Ventromentum (adj. ventromental) Ventral wall of double-walled mentum, can include ventromental plates

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