Lachlan: New Gnathothlibus and Theretra sphingid moths 
75 
Discussion 
Gnathothlibus fijiensis is readily distinguished from G. 
saccoi, G. vanuatuensis and the sympatric G. eras by the 
distinctive olive green colour on the forewings of the male, 
particularly in fresh specimens. It is a brighter green than 
seen on the forewings of G. saccoi males and most males 
of G. vanuatuensis. Gnathothlibus eras males from Fiji do 
not exhibit any green colouring to this degree and usually 
not at all. Elsewhere in the Australian-Pacific region, they 
are brown. Also, the forewings of G. fijiensis are much less 
heavily patterned than G. saccoi and it is a much smaller 
species than G. saccoi. The oblique line on the forewing of 
G. fijiensis is clearly straighter on all specimens examined 
than seen on G. eras. The forewings of the female of G. 
fijiensis easily distinguish it from the females of G. saccoi, 
G. vanuatuensis and G. eras by being less heavily patterned 
and the prominent dark brown post median line on G. fijiensis 
is angled distad slightly more than seen on the other three 
species and is very clearly much straighter. This is also the 
case in the males of G. fijiensis. 
The distinctive mauve lateral stripe on the outer edges of 
the tegulae above the wings on the males of G. fijiensis is not 
seen on the other three species; they all have creamy-white 
lateral stripes. The hindwing dark marginal band on male 
and female G. fijiensis is not as narrow at the apex of the 
hindwing as seen on G. saccoi and G. vanuatuensis. This 
dark brown marginal band is always much narrower overall 
in G. eras, particularly in males where it is often very thin. 
In G. fijiensis and G. saccoi this marginal band does not 
spike inwardly along vein 1A+2A as clearly as it does in G. 
eras and G. vanuatuensis. This situation is the same in the 
females of each of the four species. 
The fore-tarsi of G. fijiensis are covered in long hair scales; 
in G. vanuatuensis they are without such hair scales. On 
the underside of the hindwings of both male and female G. 
fijiensis the short, dark brown median line, beginning at the 
costa, does not touch the end of the discal cell as it does in 
G. saccoi and G. vanuatuensis. In G. eras this line is vestigial 
or entirely lacking in most specimens. 
The male genitalia of G. fijiensis (Fig. 14) differ from 
those of G. vanuatuensis (Fig. 17) in having the uncus, in 
lateral view, narrower, less arched, parallel-sided for nearly 
the whole of its length and lacks the distally enlarged apex. 
Gnathothlibus vanuatuensis also has a larger dorsal crest. 
When compared to G. fijiensis, the uncus of G. saccoi (Fig. 
19), in lateral view, is more steeply arched, slightly wider 
and distally enlarged without a dorsal crest. The sacculus 
process is not as robust as it is in G. eras (Fig. 18) and G. 
vanuatuensis and the upturned distal end of the harpe is 
slightly more needle-like and straight-sided than in either 
G. vanuatuensis or G. eras. The valvae are clearly narrower 
between the dorsal and ventral margins than in G. vanuatu¬ 
ensis and G. eras. G. eras also has a clearly concave dorsal 
margin which is straight in G. fijiensis. 
When placed in series, or side by side as individuals, all 
four species are readily separated by their different external 
morphological characters. 
Gnathothlibus samoaensis n.sp. 
Figs 5-9, 16 
Type material. Holotype 6, Samoa: Approx. 10 km S-W 
of Apia, Upolu Is. Alt. 410 m. 13°52’53.9"S 171°49’26"W 18 
Nov. 2008, R.B. Fachlan, AM K266028. Paratypes 526 6, 
49 9, all with same data as holotype but dated between 13th 
and 19th November, 2008. 4 6 6 and 1$ (AM K266029- 
K266032, and K266033 9 ) in AM, remainder in RBFC. 
Other material examined. 3 6 6 , Western Samoa: 
Mulivai Beach area, central south coast of Upolu Island, 9, 
12 May, 1985, R.B. Fachlan, in RBFC. 
Diagnosis. Head, thorax and abdomen uniform olive-green. 
Forewing upperside olive green in colour with prominent 
darker markings. The unicolorous band enclosing the stigma 
is about 5 mm wide along vein CuA,. Hindwing upperside 
ground colour orange; a dark, slightly variable, well-devel¬ 
oped terminal band from apex to tornus at least 2 mm wide 
with most specimens exhibiting some dark scaling along 
inner margin from tornus. Female forewing upperside with 
ground colour and pattern in shades of darkish brown, lacking 
olive green tinge of male but with a lustrous appearance in 
fresh specimens, particularly on the median and marginal 
areas of wing. 
Description. Male. (Figs 5,6,9,16). Antennae creamy-brown 
above, brown below; palpi olive green above, contrasting off 
white below; dorsal surface of head and prothorax darker 
olive green, remainder of thorax and abdomen uniform olive 
green; small dark median spot with vestigial posterolateral 
orange-brown on prothorax; thin lateral creamy-olive stripe 
from base of antenna to costa of forewing, continuing as 
creamy-white on the outer edges of the tegula above both 
wings. Thorax ventrally with creamy, light brown patch 
immediately posterior to palpi, remainder of narrow median 
band creamy-olive edged laterally with reddish-brown 
pilosity, dissipating as it reaches upper abdominal segments. 
Abdominal segments laterally (Fig. 9) each with distinct 
orange-brown posterior margin contrasting with olive green 
ground colour; abdomen with three small lateral black spots 
surrounded clearly by white. Fore-tibae covered in long, 
creamy, light olive hairs cales with very distinct dark, distal, 
ventral edge; proximal three segments of fore-tarsi covered 
in short, creamy hair scales above, edged ventrally with 
cream hair scales suffused with dark scales, shortest on distal 
segment, longest on proximal segment. 
Forewing upperside as in Fig. 5. Forewing length 
35.4-44.3 mm, mean 40.4 mm (n = 68). Ground colour olive 
green (brighter in fresh specimens) with darker markings on 
distal area of wing; some specimens appear browner but dark 
olive-green scaling is still clearly present on the forewings 
and body to varying degrees; small black stigma with light 
coloured centre at end of discal cell; small, dark, postmedian 
line from costa to vein Mj becoming a line of dark dots on 
each vein to vein 1A+2A; irregular submarginal patch of dark 
scales from vein M, to vein CuA,; this patch is variable; a 
prominent, dark, straightish oblique median line runs from 
costa, where it is curved distally, to inner margin; a short, 
irregular, subbasal band edged on each side by thin dark lines 
and curved gently distally, runs from costa to the dark basal 
