Nelphe Herrich-Schaeffer, [1858] vs. Eucereon Huebner, [1819]
(notes compiled 2026-10-22 from the literature; see sources at the end)

The genus Nelphe has never been separated from Eucereon by external characters
in print. It is a genitalia-based genus that Travassos revived in 1952 for the
setosum/confinis group of Hampson's Eucereon.

HISTORY

- Herrich-Schaeffer [1858] published Nelphe (as a Boisduval manuscript name) for
  four of his Charidea species: abdominalis, costulata, confinis and tigrata
  (= pica Walker). Kirby 1892 fixed confinis as type species.
- Hampson 1898 sank it into Eucereon. In his vol. 1 the group sits as nos. 1115
  setosum, 1116 rogersi, 1117 confine, with relegata (1115a) and moeschleri
  (1115b) added in Suppl. 1 (1914).
- Travassos 1952 (Rev. Bras. Biol. 12(3): 325-330 and 12(4): 369-384) revived
  Nelphe on genitalia, kept Galethalea Butler for pica, and transferred setosa,
  rogersi, relegatum, moeschleri and mara as new combinations, adding arpi and
  hagmanni.
- Pinheiro 2016 (Zootaxa 4079: 487-494) added trimaculata (Haiti) and dominica
  (Dominica) and counts 13 species: amazonum, arpi, carolina, confinis,
  confusum, dominica, hagmanni, mara, moeschleri, relegatum, rogersi, setosa,
  trimaculata. Her genus-level comments are in the paywalled article; only the
  two species treatments are accessible (Plazi).

TRAVASSOS'S GENERIC CHARACTERS (translated from the Portuguese)

- Palpi 3-segmented, the distal segment much reduced, upturned but not reaching
  the level of the vertex. (Hampson's Eucereon diagnosis: palpi "upturned to
  vertex of head, the 3rd joint moderate".)
- Antennae with long pectinations in the male, very short ones in the female.
- Hind wing Sc much reduced in the male, arising just beyond the middle of the
  cell and not reaching the margin; entirely absent in the female.
- Male genitalia: two long scent organs invaginated on the ventral side of the
  7th segment; armature heavily sclerotised; valvae very strong, narrow and
  long, joined by a large, strongly sclerotised juxta; aedeagus simple, vesica
  unarmed. Female: complex bursa of a thin-walled sac plus a round thick-walled
  one.
- Travassos states explicitly that the species are so alike in colour and
  pattern that only comparison of figures, and really only genitalia, allows
  identification.

Two groups within Nelphe (Travassos 1952b):
- confinis group (confinis, moeschleri, arpi): relatively broader wings with
  sharper spots; a Sc rudiment in the male hind wing; slightly asymmetric
  valvae, curved subconical aedeagus; female 8th sternite with a median
  digitiform process.
- relegatum group (relegatum, mara, hagmanni): longer wings with larger, less
  distinct spots on a darker ground; no Sc rudiment in the male hind wing;
  equal valvae, straight cylindrical aedeagus; female 8th sternite with a deep
  median notch.

AGAINST GALETHALEA (the pica group): Nelphe has large functional valvae with big
transtillae, whereas in Galethalea the valvae are rudimentary and fused to the
vinculum.

AGAINST EUCEREON SENSU STRICTO: no diagnosis has been published. Hampson's
Sect. I (type archias) is defined by male lateral tufts of long hair from the
basal abdominal segment and a lobed, thickly scaled hind wing tornus. Travassos
only said that Eucereon as Hampson conceived it belongs in Arctiidae rather than
Ctenuchidae and announced a study of it that apparently never gave a comparative
diagnosis.

PRACTICAL: the authors define Nelphe by the shared wing pattern: pale grey to
whitish ground, dark veins edged with ochreous or olive-yellow, transverse rows
of elongate dark spots ringed with yellow, semihyaline whitish hind wings with
dark veins and narrow margins, and an ochreous-yellow abdomen with a dark brown
triangular basal patch above and a white venter. A specimen with that pattern is
a Nelphe; the species inside it is the hard part.

SOURCES
- Herrich-Schaeffer, G.A.W. [1855-1858]. Sammlung aussereuropaeischer
  Schmetterlinge 1: 74, 81; figs 275-278.
- Hampson, G.F. 1898. Cat. Lep. Phal. 1: 485 (genus), 508-510 (nos. 1115-1117);
  1914, Suppl. 1: 342-343 (1115a relegata, 1115b moeschleri).
- Travassos, L. 1952a. Contribuicao ao conhecimento dos Arctiidae. XXIX. Genero
  Nelphe H.-Schaeffer, 1858. Rev. Bras. Biol. 12(3): 325-330.
- Travassos, L. 1952b. Contribuicao ao conhecimento dos Arctiidae. XXX. Especies
  do genero Nelphe H. Schaeffer, 1855. Rev. Bras. Biol. 12(4): 369-384.
  (Both downloaded from archive.org, OCR in tmp/nelphe/.)
- Travassos, L. 1952. Contribuicao ... XXVIII. Galethalea Butler, 1876. Rev.
  Bras. Biol. 12(2): 151 ff.
- Pinheiro, L.R. 2016. Description of two new species of Nelphe Herrich-Schaeffer,
  with comments on the genus. Zootaxa 4079(4): 487-494.
- funet: ftp.funet.fi/index/Tree_of_life/insecta/lepidoptera/ditrysia/noctuoidea/
  arctiidae/ctenuchinae/nelphe/