stargazer mysid

Crustaceana 87 (11-12) 1411-1429
DESCRIPTION OF THE ‘STARGAZER MYSID’ MYSIDOPSIS ZSILAVECZI
SP. NOV. (MYSIDA, MYSIDAE, LEPTOMYSINAE) FROM
THE CAPE PENINSULA, SOUTH AFRICA
BY
K. J. WITTMANN1,3 ) and C. L. GRIFFITHS2 )
1 ) Abteilung für Ökotoxikologie, Institut für Umwelthygiene, Zentrum für Public Health,
Medizinische Universität Wien, Kinderspitalgasse 15, A-1090 Vienna, Austria
2 ) Department of Biological Sciences and Marine Research Institute, University of Cape Town,
Cape Town, Republic of South Africa
ABSTRACT
Mysidopsis zsilaveczi sp. nov. shows colour patterns on the eye that mislead the observer in
thinking that the eyes are facing upwards, largely irrespective of their actual orientation, and have
resulted in local divers naming these animals ‘stargazer mysids’. To date, only males of the new
species could be sampled. Within the species-rich genus Mysidopsis G. O. Sars, 1864 the males of
M. zsilaveczi are characterized, besides their unique colour patterns, by a subdivided antennal scale;
by a small, mid-dorsal protuberance on the carapace; by endopods of all pleopods having a large,
expanded, plate-like exite on the basal segment; by the comparatively large, two-segmented endopod
of pleopod 1; by uropodal endopods that extend well beyond the telson; and by having a linguiform
telson with spines all along its lateral margins. The new species also shows diverse, very small, lobelike structures on basis and dactylus of thoracic endopods 3-8. Closely similar structures were for
the first time also found in Mediterranean material of M. angusta G. O. Sars, 1864 and M. gibbosa
G. O. Sars, 1864. This new species raises the number of southern African Mysidopsis species to nine,
confirming the coastal waters of this subcontinent as being one of the major hotspots of diversity in
this genus. An updated key to the Mysidopsis species from southern Africa (Namibia plus South
Africa) is provided.
Key words. — Mysidopsis, taxonomy, new species, key to species, South Africa, South East
Atlantic
ZUSAMMENFASSUNG
Farbmuster auf den Augen von Mysidopsis zsilaveczi sp. nov. suggerieren dem Beobachter, dass
die Augen weitgehend unabhängig von ihrer tatsächlichen Ausrichtung ständig nach oben blicken.
Das brachte den Tieren bei lokalen Tauchern die Bezeichnung ‘Sterngucker Mysiden’ ein. Bisher
wurden nur Männchen gefunden. Innerhalb der artenreichen Gattung Mysidopsis G. O. Sars, 1864,
3 ) Corresponding author; e-mail: [email protected]
© Koninklijke Brill NV, Leiden, 2014
DOI:10.1163/15685403-00003364
1412
K. J. WITTMANN & C. L. GRIFFITHS
wird M. zsilaveczi neben ihrer Färbung besonders durch folgende Merkmale charakterisiert: Antennenschuppe unterteilt; kleiner Buckel über der Mittellinie des Carapax; alle Pleopoden-Endopoditen
mit je einem großen, plattenartig verbreiterten Exiten am Basalsegment; Pleopod 1 mit vergleichsweise großem, zweigliedrigem Endopoditen; die Uropoden-Endopoditen überragen das Telson
deutlich; und Dornen stehen überall entlang der Seitenränder des zungenförmigen Telsons. Die neue
Art zeigt auch diverse, sehr kleine, lobenartige Strukturen an Basis und Dactylus der thorakalen Endopoditen 3-8. Sehr ähnliche Strukturen wurden erstmals auch bei mediterranen Vertretern von M.
angusta G. O. Sars, 1864, und M. gibbosa G. O. Sars, 1864, gefunden. Einschließlich der neuen Art
kennt man inzwischen neun Mysidopsis-Arten aus Südafrika und Namibia, entsprechend gelten die
Küstengewässer dieses Subkontinents als eine wichtiger Brennpunkt der Biodiversität dieses Genus.
Ein Bestimmungsschlüssel wird für die südafrikanischen Mysidopsis-Arten gegeben.
Schlüsselworte. — Mysidopsis, Taxonomie, Erstbeschreibung, Bestimmungsschlüssel für Arten,
Südafrika, Südost-Atlantik
INTRODUCTION
The new species described below was first observed by local Cape Town divers,
who named it the ‘stargazer mysid’. The species is unusual by virtue of its
comparatively robust body shape and epibenthic habit, but its most remarkable
feature is the conspicuously banded eyes, which give the illusion that the animals
are permanently gazing upwards (fig. 1).
The most recent addition to the southern African inventory of Mysidopsis G. O.
Sars, 1864, was made by Wooldridge (1988), whose description of M. buffaloensis
raised the number of known southern African Mysidopsis species to eight. The
key given by him summarizes the most important diagnostic characters of these
species, and it is modified in a condensed version below, including the ‘stargazer’
M. zsilaveczi as an additional species.
O. S. Tattersall (1969) provided a first major synopsis of the genus Mysidopsis,
listing 21 species (plus one not yet described) known at that time. Two of these
species were later transferred to the genus Americamysis Price, Heard & Stuck,
1994. Since 1970 numbers of acknowledged Mysidopsis species have more than
doubled, despite the fact that Price et al. (1994) transferred four species to the
genus Americamysis, and tentatively synonymized Mysidopsis cojimarensis Ortiz
& Lalana, 1993 with Parvimysis bahamensis Brattegard, 1969. They also queried
the generic status of Mysidopsis incisa, which has already been queried upon the
first description by Sars (1884); the accepted classification of this species is now as
Australomysis incisa (G. O. Sars, 1884). Finally, Price et al. (1994) listed 44 extant
species acknowledged by them without query. We add M. scintilae dos Reis & da
Silva, 1987, and the more recently described M. lata Bravo & Murano, 1996, M.
cachuchoensis San Vicente, Frutos & Sorbe, 2012, and M. iluroensis San Vicente,
2013. With the new species described below, this gives a total of 49 acknowledged
MYSIDOPSIS ZSILAVECZI NOV., THE ‘STARGAZER MYSID’
1413
Fig. 1. Colour patterns in adult males of the ‘stargazer mysid’ Mysidopsis zsilaveczi sp. nov.
(specimens with about 12 mm body length; C, holotype); from marine hard substrates overgrown
mainly by sponges, also by bryozoans, encrusting algae, etc., in sublittoral habitats off the Cape
Peninsula, South Africa. Note the concentric colour bands on the eyes, and the semiocellate spots on
the thorax. In situ photos by Guido Zsilavecz (Cape Town).
extant full species. For the sake of completeness one may add the subspecies M.
mortenseni cubanica Băcescu, 1968. In addition, the badly preserved body remains
of a fossil species from Oligocene deposits in Italy were tentatively referred to
Mysidopsis and described as M. oligocenicus by De Angeli & Rossi (2006) (for
agreement in gender corrected to M. oligocenica by Wittmann et al., 2014).