Mimonecteola Woltereck, 1909

Zeidler, Wolfgang, 2009, A review of the hyperiidean amphipod superfamily Lanceoloidea Bowman & Gruner, 1973 (Crustacea: Amphipoda: Hyperiidea), Zootaxa 2000, pp. 1-117 : 97-98

Genus Mimonecteola Woltereck, 1909

Mimonecteola Woltereck, 1909: 153 . Bowman & Gruner 1973: 18. Vinogradov et al. 1982: 99–100.

Type species. Mimonecteola diomedeae Woltereck, 1909 by monotypy. Type material could not be found in any major European museum or in the USNM and is considered lost. Woltereck does not mention the number of specimens at hand or the sex but merely records material from Albatross stations 4655 and 4717 ( eastern Pacific , off the coast of Peru), and illustrates a specimen measuring about 9 mm (judging from his illustration), from one of the stations. The species is briefly described and schematically illustrated, making it difficult to determine specific characters. However, the specimen figured by Woltereck clearly belongs to the genus Mimonecteola as is understood by modern taxonomists .

Diagnosis. Body length of females up to 15 mm, of males up to 11 mm. Head with short, hook-shaped rostrum. Eyes small. Antennae 1 as long as head and first 1.5 pereonites combined, or marginally longer. Antennae 2 marginally longer than A1, rarely shorter. Mandibles with rectangular shaped body; palp almost twice as long as body, length third article about 0.7x second. Gnathopoda simple. Pereopods 3 & 4 always simple. Pereopods 5–7 also simple, or P5 weakly subchelate and P7 with partly retractile dactylus, sometimes forming weak subchela with propodus.

Six species.

Sexual dimorphism. Females have a slightly more inflated pereon than males, especially in mature specimens. In males the callynophore of the first antennae is more robust with a distinct proximal lobe in mature specimens and is covered by numerous aesthetascs. Males also have very small genital papillae, medially near the base of the seventh pereopods. In M. mixta the dactylus of pereopod 5 is stronger in females and the palmate margin of the propodus has stronger setae than in males ( Fig. 42).

Remarks. Specimens of Mimonecteola are extremely rare in museum collections making it difficult to determine specific limits. The genus was established by Woltereck (1909) to accommodate his new species, M. diomedeae , which he states does not fit into any recognised family, but he retained it in the old Pygmaeidae because of similarities to Archaeoscina . Unfortunately, Woltereck’s description and corresponding figure are inadequate to characterise the species and, apart from what one can gather from the schematic illustration ( Fig. 37), Woltereck is clear on only two characters; the short dactyls of pereopods 3–7 and the expanded carpus, relative to the propodus of pereopods 3–6. In addition, it is clear from the figure that the first antennae are marginally shorter than the second.

Vinogradov (1964) tried to establish the status of M. diomedeae by describing a specimen with short dactyls, from the Indian Ocean, that he believed to be the same as Woltereck’s species. In particular he noted that the propodus of pereopod 5 has a tuft of strong setae near the anterodistal corner, a relatively obvious character not mentioned by Woltereck but also found in M. mixta Vinogradov, 1964 . Vinogradov makes no mention of the relative lengths of the antennae but, in their diagnosis of the genus, Vinogradov et al. (1982) state that “antennae II are thin, in females equal to or longer than antennae I, in males shorter”.

Following Vinogradov (1964) and Vinogradov et al. (1982), I have identified three female specimens as M. diomedeae amongst the material examined. However, two of these differ from that illustrated by Woltereck (1909) in that the second antennae are clearly shorter than the first and pereopods 4–6 are of similar length ( Fig. 44). In Woltereck’s figures, and that of Vinogradov (1964), pereopods 4 & 6 are of similar length and pereopod 5 is relatively shorter (about 0.8x). This brings into question the identity of Vinogradov’s (1964) material because my specimens are similar to that described by him but differ from Woltereck’s figure primarily in the relative lengths of the antennae. If the antennae of Vinogradov’s specimens are of similar length then they might represent M. diomedeae but if the second antennae are markedly shorter than the first then they would be most similar to my specimens which I believe represents a species separate from M. diomedeae . Therefore, I propose to describe them here as a species new to science because Woltereck’s species is practically unrecognisable and there is some uncertainty regarding the true identity of Vinogradov’s (1964) specimens, described as representing this species. Unfortunately, I have been unable to gain access to the specimens held in Russian Institutions in order to clarify the matter.

Regarding the character of carpus expanded for pereopods 3–6; all currently recognised species have pereopods 3 & 4 with the carpus expanded, relative to the propodus, but none as extreme as that illustrated by Woltereck (1909). The material referred to above and M. mixta and M. subchelata Vinogradov, 1964 also have pereopods 5 & 6 with an expanded carpus but to a lesser extend than for pereopods 3 & 4. In M. macronyx Barnard, 1932 and M. beebei Shoemaker, 1945 the carpus of pereopods 5 & 6 is not noticeably expanded and the anterior margin is straight or slightly concave.

A re-examination of the type of M. macronyx Barnard, 1932 ( Fig. 38) combined with additional material from the Dana expeditions has enabled me to firmly establish the validity of this species. It is most similar to M. beebei and may have been confused with it in the past. This may account for some of the geographic differences recorded for M. beebei by Vinogradov et al. (1982). Mimonecteola macronyx is readily distinguished from M. beebei by the relatively longer dactyls and shorter telson. Thus, in consideration of the above, six species of Mimonecteola are recognised in this review.