!6 4 DISCOVERY REPORTS 



Leptomysis apiops G. O. Sars, 1877 



1877 Leptomysis apiops G. O. Sars, p. 51. 

 19156 Leptomysis apiops, Zimmer, p. 319, fig. 9. 

 1915 c Leptomysis apiops, Zimmer, p. 167, fig. 19. 

 1941 Leptomysis apiops, Bacesco, p. 25. 



Occurrence : 



St. 274. 4. viii. 27 (day). Off St Paul de Loanda, 65-64 m., 1 adult <£, 7 mm., 1 ovig. $, 7 mm. 



St. 277. 7. viii. 27 (night). South-west of Cape Lopez, 63(-o) m., 8 S3, all imm., largest 5-5 mm., 58 9$, nearly 



all ovigerous, largest 7 mm. but many breeding at 5-8 mm. 

 St. 279. 10. viii. 27 (day). Off Cape Lopez, 58-67 m., 2 <J<J, adult, 7-5 mm. 



Remarks. These specimens agree closely with the published descriptions and figures of Leptomysis 

 apiops, except as regards the size at which they attain maturity and, in the females only, in the relative 

 lengths of the median spinules and large apical spines of the telson. 



In his description of the types Sars did not comment on any peculiarity of the eyes, but Zimmer 

 (19156, p. 319, fig. 9), examining specimens taken near to the same locality as the types, noted that 

 a group of facets in the outer proximal region of the cornea were enlarged and elongated, giving the 

 eye a peculiar distorted appearance. Later workers have confirmed this observation and the Discovery 

 specimens have eyes exactly as figured by Zimmer. 



Sars gave the length of adults from the Mediterranean as 11 mm., but in the Discovery material, 

 males are fully adult at 7 mm., while many females of 5-8-6 mm. are carrying advanced embryos. It 

 is quite common for animals from warmer waters to attain sexual maturity at a smaller size than those 

 in cooler localities. Although the Discovery specimens are smaller, they were taken in equatorial 

 waters and I have no hesitation in referring them to L. apiops, but the variations, which I find in the 

 relative proportions of the spinules and spines arming the apex of the telson, especially in the females, 

 have caused me much misgiving. The inner pair of apical spines in Sars's figure of the types are from 

 one-fifth to one-sixth of the length of the telson, but in my specimens they are fully one-third of the 

 telson in length, in juveniles and adults of both sexes. The length of the median spinules increases 

 with the age of the animal, being relatively small in young specimens. In adult males, the apex of the 

 telson is almost exactly as shown by Sars (1877, p. 18, fig. 9), with the median spinules less than half 

 as long as the long inner pair of apical spines, and the outer pair of apical spines only a little longer than 

 the spinules. In the females, however, the median spinules are much longer and may be more than 

 three-quarters of the length of the inner pair of apical spines. The distal lateral spines increase re- 

 gularly in size towards the apex of the telson, forming an evenly graduated series culminating in the 

 outer apical spines, which are almost equal in length to the inner pair. Thus in the females the contour 

 of the apex is more evenly rounded than in the males and the inner pair of apical spines does not 

 project markedly. These females are, in fact, similar to the single damaged females from the Indian 

 Ocean which Zimmer (1915 c, p. 167, fig. 19) referred doubtfully to L. apiops. 



In all other respects the Discovery specimens agree so closely with the descriptions of L. apiops 

 that, in spite of this sexual dimorphism, I feel that they must be referred to that species. I consider 

 that Zimmer's specimen from the Indian Ocean should also be referred to L. apiops. 



Distribution. Apart from the specimen mentioned above, and two questionable records from the 

 English Channel, 1 this species has never before been recorded outside the Mediterranean. Sars's 

 types were taken near Naples, and the species has been recorded by Bacesco (1941, p. 25) from the 



1 Pubs. Circs. 48, 1909 and Pubs. Circs. 70, 1916. 



