Zoonomen has Siptornis (f.) Reichenbach 1853 Handb.spec.Orn.(Icon.Syn.Av.no.10) p.146,171 so maybe Palaeornis is female and since dupha is a noun it must match gender??
In Latin, adjectives agree in gender (as well as number and grammatical case) with the noun they qualify; nouns do not. If "
duphaä" is not an adjective, its formation should not have been affected by the gender of
Paloeornis.
ὄρνις (
ornis) is a noun of common gender in Greek: a word that can be used as either masculine or feminine, usually depending on the biological sex of the denoted creature -- thus, "ὁ ὄρνις", masculine = the bird / the he-bird; "ἡ ὄρνις", feminine = the she-bird (this was often used for hens). Under the current Code, the gender of a name ending in such a word depends on how the original author used it in the OD.
Siptornis is feminine because Reichenbach originally used it as a feminine word (for a species he called
S. flam(m)ulata -- a feminine adjective).
Palaeornis is masculine because Vigors used it as masculine (including under it:
[P.] torquatus,
bitorquatus,
xanthosomus,
erythrocephalus,
pondicerianus; also calling one species a "
P[alaeornis] sanguineo-coccineus" in one of the diagnoses). But our current rules have not always be followed in the past; thus
Palaeornis has also been used as feminine by some authors (e.g., as "
Palaeornis torquata"); and
Siptornis has been treated as masculine too. It's not really possible to see which (if any) gender McClelland had in mind for his "
Paloeornis".
-
ae is a genitive ending used for a-stem words in Latin; these words include genuine Latin words with a nominative singular in -
a, and some Greek nouns passed into Latin with a nominative singular in -
e (Gr: -η), -
as (Gr.: -ας), or -
es (Gr.: -ης). Latin adjectives in -a are always feminine; most Latin nouns in -
a are feminine too, but some are masculine (just as, e.g., in Spanish); Greek nouns in -
e are feminine, Greek nouns in -
as or -
es are masculine.
An -
ae ending in a name formed from a masculine personal name ending in -a (-
a inflected to -
ae as if the name was a Latin noun) is perfectly normal whatever the gender of the dedicatee (i.e., not indicative of this gender); an -
ai ending in such a name (unmodified name + -
i, a much more artificial variant than -
ae) should in principle indicate a man; an -
aae ending (= "-
aä" if
ä stands for
ae) is not something I can remember having seen, but might arguably indicate a woman (unmodified name + -
ae: feminine equivalent of the "more artificial" masculine variant -
ai). For a people rather than a person, a genitive plural (-
arum /
-orum) would in principle be more expectable, I believe.