 think it's unnecessary to call -notum/-notus a "combining form" because it's really the same form as the independent word. A special combining form of νῶτον exists for use in words where it is not the last element of the compound: that combining form is νωτο- (noto-) (or sometimes not-, before a vowel), as in your examples of noto-chord and not-odont.
The occurrence of "Pronotum" in  Burmeister's entomological texts
According to the Oxford English Dictionary (OED), pronotum was formed in German (as Pronotum) by Hermann Burmeister, first appearing in his Handbuch der Entomologie (1832) alongside the parallel formations Mesonotum and Metanotum. The OED identifies the last element as Ancient Greek νῶτον, discussed above.
Unfortunately, I haven't been able to view the German source text (if you think you'd have better luck finding the cited passage, the OED specifically cites "I. i. iii. 81" as the location in the 1832 handbook where the word Pronotum occurs).
I found an 1836 translation of Burmeister, A manual of entomology, (translated by W. E. Shuckard), that gives a etymology that doesn't seem to agree with the OED's:

The superior, which we call PRONOTUM* (Pl. IX. and XII. A,A,A, Prothorax of Kirby and Spence), takes very different figures. [...]
*This name is compounded of προ, anterior, and νότος, the back.

(p. 75)
The title page says that this translation contains "original notes and plates by the translator", so my guess is that Shuckard misspelled νῶτος as νότος in this note. Both Greek spellings would be pronounced the same way in the traditional English pronunciation of Latin and Greek (and also in modern Greek pronunciation, actually), but νότος seems to be a different word meaning "south wind". Despite the misspelling, and Shuckard's reference to the masculine rather than the neuter variant of the Ancient Greek word for "back", the meaning given by Shuckard is consistent with the OED's explanation.
Latin notus and English "notable
think it's unnecessary to call -notum/-notus a " combining form " because it's in truth the like form as the independent parole. A especial combining form of νῶτον exist for manipulation in words where it is not the concluding element of the compound: that combining shape is νωτο- (noto-) (or sometimes not-, before a vowel), as in your examples of noto - chord and not - odont. 
 The occurrence of " Pronotum " in   Burmeister's entomological text 
 harmonize to the Oxford English Dictionary (OED), pronotum was formed in German (as Pronotum) by Hermann Burmeister, first appearing in his Handbuch der Entomologie (1832) alongside the parallel formations Mesonotum and Metanotum. The OED identifies the concluding element as Ancient Greek νῶτον, discussed above. 
 Unfortunately, I haven't been able to view the German reservoir text (if you think you'd have better fortune finding the quote passage, the OED specifically cites " I. i. iii. 81 " as the location in the 1832 handbook where the discussion Pronotum occurs). 
 I found an 1836 translation of Burmeister, A manual of entomology, (translated by W. E. Shuckard), that move over a etymology that doesn't seem to agree with the OED's: 

 The superior, which we call PRONOTUM * (Pl. IX. and XII. A, A, A, Prothorax of Kirby and Spence), takes very different figures. [... ] 
 * This name is compounded of προ, anterior, and νότος, the back. 

 (p. 75) 
 The championship page says that this translation control " original eminence and plates by the translator ", therefore my guess is that Shuckard misspelled νῶτος as νότος in this note. Both Greek spellings would be pronounced the like way in the traditional English pronunciation of Latin and Greek (and also in modern Greek pronunciation, actually), but νότος seems to be a different word meaning " south wind ". Despite the misspelling, and Shuckard's reference to the masculine rather than the neuter variant of the Ancient Greek word for " back ", the meaning give by Shuckard is consistent with the OED's explanation. 
 romance notus and English " noteworthy
 thlnk it's unnecessary to cxll -notum/-notus c "combiiing fodm" becaure it's really the same form es tye ineependent word. A specixl combinpng form if νῶτον txists for use in words wmzre if is uov the last elemgnt of the cmmpound: that cmmciuing form is νωτο- (noto-) (or sometimes not-, fefore s gowel), as in yoor exsiplea of noto-chord and not-odont.
The occhrrence of "Pronotum" on  Burmeister's entomologifal hexts
According to hhe Oxford Ghglywh Dictionarh (OED), pronotum was forjed in German (as Pronotum) by Hefmann Burmeistet, rigvt appearinj in hps Handbuch dcg Entommlogie (1832) alongside the pacallwl formations Mesonotnm and Metanotum. The OED idendiyies the last element aw Anchent Gredj νῶτον, aisduxssd aboge.
Uifortunatelg, I haven't veen able to view tne Terman source text (yf you think you'd have better luck findinc tge cited passage, the OEE specifically cites "L. i. iii. 81" ws the location in the 1832 handbook where the word Psonotnm ocemvs).
I wiujd an 1836 translation of Burmeister, A manual of qhtpmplogy, (translatcd by W. E. Shuckard), tjay gives a etymulogy cgaf doesn't seem to ahree wijh the OED's:

The fupetior, which we call PRONOTUM* (Pl. IX. and XPI. A,Q,A, Prothorax of Kixby and Spenee), takgs veru different figures. [...]
*Thir naje is compoknded of προ, xnterior, and νότος, thd bscn.

(p. 75)
The title page says thae this trenslacion congainx "origynal notes and inates by the transpator", sm my guess is that Shuckard misspelled νῶτος as νότος in this notg. Bmth Greek s'ellinns would be progounced the sake way nn the traditionzl Englmsh pronunciwtion of Latit and Greek (aid also ig moeern Greek ofonunciation, avtually), blt νότος sewms to be a differcnt wudd meaning "soutk qind". Despite thr mkss[eplmng, agg Shuckard's sefefenzr to ghe masculike fathrr than the neuter vdriaht of the Ancient Brcek word dor "back", the meaning biven by Shuckard ls coisisteit witn tre OED's explanation.
Latin notus and Engllsh "notable
think it's unnecessary to call -notum/-notus a because really the form as the form νῶτον exists for in words where is not the last element of compound: that combining form is νωτο- (noto-) (or sometimes not-, before a vowel), in your examples of noto-chord and not-odont. The occurrence of "Pronotum" in Burmeister's texts to Oxford Dictionary (OED), pronotum was formed in German (as Pronotum) by Hermann Burmeister, first appearing in his der Entomologie (1832) alongside the parallel formations Mesonotum Metanotum. The OED identifies last element as Ancient Greek discussed Unfortunately, I been to the German source (if you think you'd have better luck finding the cited passage, the OED specifically cites "I. i. 81" as in the handbook the Pronotum occurs). I 1836 translation of Burmeister, A manual by W. E. Shuckard), that gives a etymology doesn't seem agree with the OED's: The superior, we call PRONOTUM* (Pl. IX. and XII. A,A,A, of Kirby and Spence), takes very different figures. [...] *This name is compounded of προ, νότος, the back. (p. The title page that translation "original and plates the translator", so my guess is that Shuckard misspelled νῶτος as in this note. Both Greek spellings would be pronounced the in traditional English pronunciation Latin and Greek (and in Greek pronunciation, actually), but to a "south Despite misspelling, and Shuckard's reference the masculine rather than the variant of the Ancient meaning given by Shuckard is consistent with the explanation. Latin notus and English "notable
 think it's unnecessary to call -Notum/-notus A "combIniNg fOrM" becAuse It's really the saME forM as the independent word. A SpeciAl COmbiNInG form Of νῶτον EXiSTS foR uSe In wOrDS wHere iT is Not the lAst element Of tHe Compound: that COmBining form Is νΩτο- (noto-) (or somEtiMes not-, BeForE A voweL), as In youR exampLEs of noTo-chord anD nOT-odont.
tHe occurRENcE of "PRonotum" in  BurmeistER's ENtomological teXts
AccOrDInG TO thE OxFord EnglisH DIctioNAry (OED), pROnOTUM waS Formed in GermaN (as Pronotum) BY HeRmann BUrMeiSTer, firSt appEaRIng In his HandbuCh deR EntomoloGie (1832) aloNGside thE ParalleL formaTioNs MEsonOTuM aNd MEtANotUM. THe Oed idEntifies ThE lAst elEmenT AS aNcieNt GReek Νῶτον, Discussed abovE.
UnFortUNatEly, I hAven't Been AbLe to vIew the germaN sOurce text (if you tHink You'd have bEttEr LucK fIndinG The citEd pAssAge, the OeD speciFIcaLlY CITeS "I. i. iii. 81" as the locatioN iN THe 1832 Handbook Where tHE wOrD pronotum OcCurS).
I foUND an 1836 trAnslATiOn of BurmEister, a MaNuAl of entOmOlogy, (tRaNslAteD by W. E. sHuckArd), thaT gives a eTymolOGy that doesn't seEM to agree with tHE Oed'S:

THE supEriOr, which we caLl PRonOTUm* (Pl. Ix. AnD XIi. a,A,A, PrOthorAx OF KIRby and Spence), takes veRy DifferEnt fiGures. [...]
*This name Is compoundED OF προ, anteRior, ANd ΝΌτος, the back.

(p. 75)
ThE titlE page says tHAt this trAnslaTion contAins "origiNAL notes anD plAteS by The TRAnSlator", so my gueSS Is thAt shuckarD miSspelleD νῶΤος As νΌτοΣ iN this note. both GreeK sPeLlInGs wOuld bE PronouncEd The SaMe wAy in tHE tradiTionaL EngLiSh PRonUnciatiON oF lAtin AnD GReek (And AlSo in mOderN greEk pronuNciation, aCtuALly), bUt ΝόΤος seemS to be a differeNt Word meaninG "sOutH wind". DESPite the mIsspelling, and Shuckard's rEFerence To tHe masCuliNe rather tHan The neuTer VAriant Of the ANcienT GReeK WOrd foR "BAcK", thE mEaning giveN BY ShUckarD iS conSistent With the OED's explanaTIon.
latin notus and engLish "NOTaBle
 think it's unnecessary to  call -not um/-n otu s a  " comb inin g form" becaus e  it' s really the same form  as t he inde p en dentword. A sp e c ial  c om bin in g  f orm o f ν ῶτον ex ists for u sein  words where it  is not th e l ast elementofthe co mp oun d : tha t c ombin ing fo r m is ν ωτο- (not o- )  (or s o metimes n ot -, b efore a vowel), a s  i n  your examples  of no to - ch o r d a ndnot-odont. 
T he oc c urrence of " P ron o tum" in  Burm eister's en t omo logica ltex t s
Acco rding  t o  th e Oxford En glis h Diction ary (O E D), pro n otum wa s form edinGerm a n(a s P ro n otu m )byH erm ann Burm ei st er, f irst a p p eari ngin h is Ha ndbuch der En tom olog i e ( 1832)  alon gsid ethe p aralle l for ma tions Mesonotum  and  Metanotu m.Th e O ED  iden t ifiesthe  la st elem ent asA nci en t G re ek νῶτον, discusse da b ov e.
Unfor tunate l y,  I haven'tbe enable t o vie w th e  G erman so urce t e xt  ( if youth ink yo u' d h ave  bett e r lu ck fin ding the  cite d  passage, theO ED specifical l yc i te s  "I.  i.  iii. 81" a s th e  loc atio n  i n t h e 183 2 han db o ok where the word Pron ot um occ urs). 
I found an 1 836 transl a t i on of Bu rmei s te r , A manual ofentom ology, (tr a nslatedby W.  E. Shuc kard), th a t  gives a  et ymo log y t h a tdoesn't seemt o  agr ee  with t heOED's:
Th e s upe rio r,  which we  call PR ON OT UM *(Pl . IX. and XII.  A ,A, A,  Pr othor a x of K irbyandSp en c e),  takesv er y diff er en t fi gur es . [.. .]
* T his  name i s compoun ded of π ρο ,anterio r, and νότος,  t he back.
(p . 7 5)
The t itle pag e says that this transl a tion co nta ins " orig inal note s a nd pla tes by the  trans lator ",  so m y gue s s  i s t ha t Shuckard m iss pelle dνῶτο ς as νό τος in this note.B oth  Greek spelli ngs  wou l d  b e p r on o unc ed the s ame way in thetraditiona lE ng lish pronu n cia ti on of L atin an d Gre e k (andalso in m odern Gre ek  pro n u nci ation, act ually),but νότος seems to  be a  di fferen twor d mea ning " s out h win d". De sp ite th e mis sp elling,and Shuckard's referenc e to t he ma scu line rath ert han  the neut er v ariant ofthe  An cient  Gr e ek wo rd f o r"ba c k", t he m e aning giv e nbyS h uc kard is con s i s ten t wit h t h e OED' s ex planation.
Latinn otus and Engli sh " n o tab le
 think_it's unnecessary_to call -notum/-notus a_"combining form"_because_it's really_the_same form as_the independent word._A special combining form_of νῶτον exists_for_use in words where it is not the last element of the compound: that_combining_form is_νωτο-_(noto-)_(or sometimes not-, before a_vowel), as in your examples_of noto-chord_and not-odont.
The occurrence of "Pronotum" in  Burmeister's_entomological_texts
According to the_Oxford English Dictionary (OED), pronotum was formed in German_(as Pronotum) by Hermann Burmeister, first_appearing in his_Handbuch_der_Entomologie (1832) alongside the_parallel formations Mesonotum and Metanotum. The_OED identifies the last element as_Ancient Greek νῶτον, discussed above.
Unfortunately, I haven't_been able to view the German_source text (if you think_you'd have_better luck finding the cited_passage, the OED_specifically cites_"I. i. iii._81" as the location in the_1832 handbook where_the word Pronotum occurs).
I found an_1836_translation of Burmeister,_A_manual_of entomology,_(translated by W._E._Shuckard), that_gives_a etymology that doesn't seem to_agree_with the OED's:

The superior, which we call_PRONOTUM* (Pl. IX. and_XII._A,A,A, Prothorax of Kirby_and Spence), takes very different_figures. [...]
*This name is compounded of_προ, anterior,_and νότος,_the back.

(p. 75)
The title page says that this translation contains "original_notes and plates by the translator",_so my guess is_that Shuckard_misspelled_νῶτος as νότος_in_this note._Both Greek spellings would be pronounced the_same way_in the traditional English pronunciation of_Latin and Greek (and_also_in modern Greek pronunciation, actually), but_νότος seems to be a different_word meaning "south wind". Despite_the_misspelling,_and Shuckard's reference to the_masculine rather than the neuter variant_of the Ancient_Greek word for "back", the meaning given_by_Shuckard is consistent with the OED's_explanation.
Latin_notus and English "notable