PEREZ FARFANTE: REVISION OF PENAEID SHRIMP GENUS PENAEOPSIS 



sternite XIII, plate on stemite XIV elongate and 

 bearing paired seminal receptacles disposed lon- 

 gitudinally rather than transversely. Pleuro- 

 branchia on somites IX-XIII; rudimentary, 

 filamentose arthrobranchia on somite VII, an- 

 terior and posterior arthrobranchiae on somites 

 VIII-XII, and only posterior arthrobranchia on 

 somite XIII. Epipod on first maxilliped (if proxi- 

 mal exite of coxa is considered an epipod) and 

 second maxilliped and on first to third pereopods. 



In this genus the petasma is structurally very 

 simple, consisting of a plain trough that is 

 neither produced as distal or distolateral hornlike 

 or broad projections, nor bears distal elements as- 

 sociated with the four lobules. The pestasmal 

 lobules are reinforced by plates and ribs: a distal 

 plate and a proximal plate on the dorsomedian 

 lobule, and two longitudinal ribs. One of the lon- 

 gitudinal ribs extends along the dorsolateral 

 lobule and is typically produced proximally as a 

 process the shape of which varies with the 

 species, the other rib forms the ventral costa and 

 occupies the free margin of the ventrolateral 

 lobule. This petasma is similar to that of the 

 genus Penaeus, but, in other respects, Penaeopsis 

 does not resemble the latter; instead, it is closely 

 related to Metapenaeopsis which, surprisingly, 

 exhibits an asymmetrical petasma that is also the 

 most complex among the Penaeoidea. 



Small juvenile Penaeopsis are armed with £m 

 anteriorly directed, sharp spine on sternites XIII 

 and XIV. Both spines disappear in larger males, 

 whereas in females that on sternite XIII is either 

 lost or persists, although considerably reduced, at 

 the apex of the median plate, which, in itself, rep- 

 resents an expansion of the basal portion of the 

 spine. The spine on sternite XIV disappears en- 

 tirely or becomes incorporated in the median 

 ridge or protuberance of that sternite. As Bur- 

 kenroad (1934a) has stated, the occurrence of 

 these sternal spines is a larval character present 

 on the postmysis stages of many Penaeidae. 



Despite the homogeneity of the few species (six, 

 of which only four were known prior to 1976) cur- 

 rently assigned to the genus Penaeopsis, the first 

 three described were assigned to two genera 



(Bate 1881). Subsequently, various authors have 

 referred Bates species to four different genera. 

 Schmitt (1926) contributed to our knowledge of 

 the genus when he recognized common 

 superspecific characters in the "small 'Penaeopsis 

 serratus' group." Unfortunately, the characters 

 he chose led him to include within this as- 

 semblage two species that are currently recog- 

 nized as members of the genus Metapenaeopsis: 

 M. coniger (Wood-Mason 1891) and M. an- 

 damanensis (Wood-Mason 1891). Schmitt cited 

 the absence of anterior arthrobranchia on somite 

 XIII as one of the characters of the "group," a 

 valid Penaeopsis character common to all of the 

 species except those two mentioned above, which 

 he assigned to Penaeopsis although he was aware 

 that they possessed such arthrobranchia. 



A few years later Burkenroad (1934a) pre- 

 sented an enlightened discussion of two of the 

 four Series — Parapenaeus and Trachypenaeus 

 — into which he ( 1934b) divided the Penaeinae [ = 

 Penaeidae]. His excellent choice of characters for 

 the definition of the genera resulted in very few 

 changes in his classification during the 45 yr that 

 have elapsed since the publication of the two con- 

 tributions. Among the few alterations that have 

 been made in the taxa recognized by him was the 

 reelevation of Metapenaeopsis to generic rank; he 

 had considered Penaeopsis and Metapenaeopsis to 

 be subgenera of the genus Penaeopsis. The mem- 

 bers of these two species-groups are closely allied, 

 because both species-groups possess a carapace 

 lacking longitudinal and transverse sutures but 

 bearing pterygostomian spines, two or more 

 well-developed movable spines on the lateral 

 margins of the telson anterior to the fixed pair, 

 and exopods on all maxillipeds and pereopods. 

 However, the two taxa exhibit characters that are 

 now considered to be of generic value, i.e., bran- 

 chial formula, thelycal features, and basic struc- 

 ture of both the petasma and appendix masculina 

 ( for a detailed account of Metapenaeopsis see Perez 

 Farfante 1971). These characters were employed 

 by Kubo (1949) in diagnosing the two groups as 

 distinct genera, a revision that is now generally 

 accepted. 



Key to Species of Penaeopsis 



1. Telson bearing three pairs of movable spines 2 



Telson bearing two pairs of movable spines 3 



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