A Grammatical Dictionary of Botanical Latin

-theca (s.f.I), -thece (s.f.I): in Gk. comp. -theca.

The declension of generic names that end in -a (-theca) are different in the singular from those ending in -e (-thece).

1. Those that end in -a are declined in the singular and plural according to the standard Latin first declension.

2. Those ending in -e are declined differently in the singular, but according to the standard Latin first declension in the plural (see Stearn 1983 p. 70); 1. -theca,-ae (s.f.I);

       singular          (the plurals are with standard endings)
Nom. Dimorphotheca                 -thecae
Gen. Dimorphothecae                -thecarum
Dat. Dimorphothecae                -thecis
Acc. Dimorphothecam                -thecas
Abl. Dimorphotheca                 -thecis

Acanthotheca, Arctotheca, Campylotheca, Dimorphotheca, Gonotheca, Helminthotheca, Heterotheca, Omalotheca, Podotheca, Rhabdotheca, Stenotheca, Trigonotheca

2. -thece,-es (s.f.I), generic name ending in;
       singular          (the plurals are with standard endings)
Nom.  Aphanothece                      -thecae
Gen.  Aphanotheces                     -thecarum
Dat.  Aphanothecae                     -thecis
Acc.  Aphanothecen                     -thecas
Abl.  Aphanothece                      -thecis

Aphanothece, Cyamathece

-thecal, -thecous: -thecalis,-e (adj.B), -thecus,-a,-um (adj.A);

- hypothecalis,-e (adj.B), hypothecus,-a,-um (adj.A), relating or belonging to the hypotheca of a Diatom.

-theca,-ae (s.f.I); theco-: in Gk. comp., -cover, -case, -container; (in fungi) “case, sac, capsule” (S&D);

- bibliotheca,-ae (s.f.I): library, collection, list or catalogue of books.

- used of various exsiccatae: Bryotheca Braziliensis, Hepaticotheca Polonica.

- hypotheca,-ae (s.f.I), abl. sg. hypotheca, ‘the inner half-frustule of a Diatom’ (Jackson after O. Mueller).

Acanthothecomyces: Acantho- theco- -myces.