Trichromia onytes (Cramer, [1777])

Cock, Matthew J. W. & Laguerre, Michel, 2021, Taxonomic changes in the Neotropical Arctiinae, Arctiini (Lepidoptera, Erebidae) relating to the fauna of Trinidad and Tobago, Zootaxa 5071 (2), pp. 253-270 : 261-264

Trichromia onytes (Cramer, [1777])

Figs. 6–9 . BIN: BOLD:AAG6256 (dx.doi.org/10.5883/BOLD:AAG6256)

Cramer described Phalaena Noctua onytes from Surinam ( Cramer [1777], pp. 107, 150, plate 165E) and Sphinx Adscita psamas Cramer, [1779] from Guyana ( Berbice) and Suriname ( Cramer [1779], pp. 72, 176, plate 234G). We are not aware of any surviving type material (Cramer gives no details for P. onytes , while P. psamas was from the collection of Mr. A. Gevers), but Cramer’s figures ( Fig. 6 ) serve to recognise both taxa; the dark grey hindwing in particular is distinctive.

Hampson (1901) placed them both in the genus Neritos Walker, 1855 , with psamas as the male of the female onytes . However, he subsequently realised that he had misidentified the male that he had used to illustrate the male of this species (i.e. Hampson 1901, Fig. 100) and described it as N. macrostidza Hampson, 1905 ( Hampson 1905, 1920). In the same works, Hampson maintained N. psamas as the male of N. onytes , noted that in the male the yellow patches on costa and termen may be confluent or separate, and gave the distribution as Panama, Guyana, French Guiana, Bolivia and Peru.

Rothschild (1910) held a different opinion and recognised N. psammas [sic] which he knew only from males from Trinidad and the Guianas, and N. onytes which he knew only from females from Suriname and British Guiana. However, Seitz (1920–1925) followed Hampson (1905, 1920) but added that the female as well as the male occurs with the yellow spots both separate and joined.

Watson and Goodger (1986) reinstated Neritos psamas as a valid species, and placed onytes in Trichromia Hübner, [1819] , of which it is the type species. They offered no explanation for the former action, but explained that most of the species placed in Neritos in their list would need to be transferred to Trichromia . Toulgoet (1991) clarified the composition of Trichromia , made Neritos a synonym and made the new combination Trichromia psamas . There have been no subsequent changes and both species are currently treated as valid and placed in Trichromia ( Vincent and Laguerre 2014) . Through these different changes, no one reported examining and comparing the genitalia of T. psamas and T. onytes . There are public barcodes for T. onytes in BOLD from Brazil and French Guiana (BIN BOLD:AAG6256) and both morphs are included in this BIN (dx.doi.org/10.5883/BOLD:AAG6256).

In Trinidad and French Guiana, we have observed that T. onytes and T. psamas are the two principle morphs of a single variable species that occurs with the yellow discal forewing band uninterrupted ( Fig. 7A–B ), with it split by the apical patch being joined to the basal-discal one ( Figs. 7C, E–F , 8B ), and occasionally as in intermediate morph with the band only very narrowly interrupted ( Figs. 7D , 8A ). We compared dissections of males of both main morphs from Trinidad and French Guiana and found the genitalia to be identical ( Fig. 9 ). Noting also the occurrence of intermediate morphs, it is clear that Hampson (1901, 1905, 1920) and Seitz (1920–1925) were right, and the two names are synonyms, T. psamas being a syn. rev. of T. onytes . Where it is useful to distinguish these two morphs, they may be referred to as onytes morph and psamas morph.

Material examined. Trichromia onytes onytes morph: FRENCH GUIANA: 2♂ Piste de Kaw, PK 36, 6– 7.viii.1994 [ ML one ♂ dissected Gen. ML3370 ]. ♂ Piste de Kaw, PK 41, 25.i.1996 [ ML]. 2♀ Piste de Kaw , PK 38, 19.i.1996; 3♀ same data but 20.i.1996 [ ML]. ♀ Piste de Kaw , PK 36, 6.viii.1994 [ ML]. 2♀ Piste de Kaw , PK 36, 11 & 13.viii.1994 [ ML]. TRINIDAD AND TOBAGO, TRINIDAD: Arima Valley, Simla, MVL: ♂, ♀ 28.ix.1981 (M.J.W. Cock) [ MJWC]. Balandra, at light: ♂ 21.viii.1969 (F.D. Bennett) [ UWIZM CABI.1124]. Cumaca Road, 4.6 miles, MVL: ♀ 18.vii.1981 (M.J.W. Cock) [ MJWC]; ♂, 2♀ 21.x.1982 (M.J.W. Cock) [ MJWC]. Curepe, MVL trap: ♀ i.1971 (R.E. Cruttwell) [ UWIZM CABI.1122]. Morne Bleu, Textel Installation, at light: ♀ 5.ix.1978 [ UWIZM CABI.1127]. Rio Claro-Guayaguayare Road , milestone 6.5, MVL: ♀ 30.ix.1978 (M.J.W. Cock) [ UWIZM CABI.1126]. Valencia Forest , MVL: ♂ 31.vii.1980 (M.J.W. Cock) [ MJWC, dissection 1105]; ♀ 5.viii.1981 (M.J.W. Cock) [ MJWC]. VENEZUELA: ♂, ♀ Bolivar, Road El Dorado - Sta Elena, PK 38, 16.viii. 1996, 200 m [ ML] .

Trichromia onytes psamas morph: FRENCH GUIANA: 3♂ Piste de Kaw, PK 36, 5–6.viii.1994 [ ML]. 2♂ Piste de Kaw, PK 38, 19.i.1996 [ ML, one ♂ dissected Gen. ML3371 ]. 2♂ Piste de Kaw , PK 37, layon km 3.3, 24.vii.2001 [ ML]. ♂ Piste de Kaw , PK 38, 21.i.1996 [ ML]. ♂ Piste de Kaw , PK 38, 10.ii.1999 [ ML]. VENEZUELA: ♂ Bolivar, Road El Dorado - Sta Elena , 6.viii.1995, PK 70, 250 m [ ML]. ♂ Bolivar, Road El Dorado - Sta Elena, PK 38, 16.viii. 1996, 200 m [ ML]. ♂ Bolivar, Road El Dorado - Sta Elena, PK 13, 5.viii. 1995, 100 m [ ML]. TRINIDAD AND TOBAGO, TRINIDAD: Arima Valley, Simla, MVL: ♂ 5.v.1989 (R.G. Brown) [ UWIZM CABI.1123]. Caparo: 2♂ xi.1905 (S.M. Klages) [ NHMUK]. Chatham: ♂ 5.i.1985 (M. Alkins) [ UWIZM.2014.9.1291]. Cumaca Road, 0.5 miles, MVL: ♂ 27.x.1980 (M.J.W. Cock) [ MJWC]. Cumaca Road, 4.6 miles, MVL: ♂ 18.vii.1981 (M.J.W. Cock) [ MJWC, dissection 1106]; 1♂ 21.x.1982 (M.J.W. Cock) [ UWIZM CABI.8017]. Hollis Reservoir, at light: ♂ 2.xi.1978 (M.J.W. Cock) [ UWIZM CABI.1121]. Morne Bleu, Textel Installation, at light: ♂ 20.ix.1978 (M.J.W. Cock) [ MJWC]. Valencia Forest , MVL: ♂ 31.vii.1980 (M.J.W. Cock) [ UWIZM CABI.1125] .

Trichromia onytes intermediate morph: TRINIDAD AND TOBAGO, TRINIDAD: Balandra , at light: ♂ viii.1970 (F.D. Bennett) [ UWIZM CABI.1128]. Caparo: ♂ (S.M. Klages) [ NHMUK]. Inniss Field, MVL: ♂ 17.v.1999 (M.J.W. Cock) [ MJWC] .

Figures

FIGURE 6. Cramer’s published figures of female Trichromia onytes (Cramer [1777], plate 165E) (edited from Biodiversity Heritage Library) and male T. psamas (Cramer [1779], p. 72, plate 234G) (edited from an original copy).

FIGURE 7. Trichromia onytes from Trinidad (M.J.W. Cock) [MJWC]. A–B, psamas morph, dorsal and ventral views, Morne Bleu Textel Installation, at light, 20.ix.1978, 29 mm. C, onytes morph (dissected), dorsal view, Valencia Forest, MVL, 31.vii.1980, 30 mm. D, intermediate morph, dorsal view, Inniss Field, MVL, 17.v.1999, 31 mm. E–F, female onytes morph, dorsal and ventral views, Cumaca Road, 4.6 miles, MVL, 18.vii.1981, 31 mm. Not to scale; wingspans in legend.

FIGURE 8. Live Trichromia onytes. Left, male intermediate morph, Trinidad, Brasso Seco, 14.iii.2015 (K. Sookdeo). Right, female psamas morph, Trinidad, Grand Riviere, 16.v.2015 (K. Sookdeo). Not to scale. © K. Sookdeo, with permission.

FIGURE 9. Male genitalia of Trichromia onytes onytes morph (ML3370) (above) and T. onytes psamas morph (ML3371) (below) from French Guiana, Kaw Road.A, dorsal view; B, ventral view; C, lateral view; D, aedeagus lateral views.All to scale as shown.