Alpheus paracrinitus Miers, 1881
Click for larger version of picture A Click for larger version of picture B
| Original Description | Alpheus paracrinitus Miers, 1881b: 365, pl. 16, fig. 6. |
| Classification | Arthropoda: Crustacea: Malacostraca: Decapoda: Alpheidae. |
| Synonymy | (?) Alpheus ascensionis Ortmann, 1893; (?) Crangon togatus Armstrong, 1940; (?) Alpheus paracrinitus sp. B in Williams et al., 2001. |
| Type Locality | Goree, Senegal (symbol  on the map). |
| Type Material | NHM 000000 (syntypes), in ethanol, condition: ????. |
| Common Name | Miers' banded snapping shrimp. |
| Taxonomic Status | Valid but taxonomic status unclear (Anker et al., in prep.), nominal species of a worldwide species complex. |
| Geographic Distribution | Tropical eastern, central and western Atlantic [EA-CA-WA]: Cape Verde to Gulf of Guinea and south to Angola; Ascension Island; Bermuda and throughout Caribbean region to Panama and Brazil (see map). |
| Frequency | Fairly common. |
| Habitat | Sandy-rocky bottoms, also sand patches with rubble on coral reefs and sea grass with rubble. |
| Depth Range | Intertidal and shallow subtidal to about 10 m. |
| Life History and Behavior | Free-living, in pairs or single under rocks and in crevices in algal conglomerates and coral rubble; occasionally among black corals, Antipathes sp. (Türkay, 1982). |
| Related Species | Alpheus "coeruleocinctus" Anker et al., in prep. [EA]; A. "subparacrinitus" (Anker et al., in prep.) [WA]; A. fasciatus Lockington, 1878 [EP]; A. aff. paracrinitus (Anker, pers. obs.) [IWP]; A. "pararostratus" Anker et al., in prep. [EA]; A. "geminirostratus" Anker et al., in prep. [WA]; A. rostratus Kim and Abele, 1988 [EP]; A. aff. rostratus (Anker, pers. obs.) [IWP]; A. bengalensis Coutière, 1905 [IWP]; A. alpheopsides Coutière, 1905 [IWP]; A. paralpheopsides Coutière, 1905 [IWP]; A. tenuipes De Man, 1910 [IWP]; A. mitis Dana, 1852 [IWP]. Alpheus paracrinitus is extremely difficult to distinguish from other species without knowing the color pattern. ?For instance, A. paracrinitus differs from A. "coeruleocinctus" by the more slender, purple-reddish (instead of bluish) bands, without notch on the sixth abdominal segment (see comparison photos); from A. fasciatus by the different pattern of the major chela; from A. "pararostratus", A. "geminirostratus", A. rostratus and A. aff. rostratus by the very different color pattern on the major chela and absence of dark dorsal spots on the third abdominal somite (see comparison photos); from A. bengalensis by the second pereiopod with the first carpal segment longer than the second (the two segments being subequal in A. bengalensis) and the minor chela with acute distal tooth on the palm (without such a tooth in A. bengalensis); from A. aff. paracrinitus by the dark purple-red (instead of pink-red) bands and a more marked pattern on the major chela (see comparison photos); from A. alpheopsides by the longer rostrum and presence of small orbitorostral process (absent in A. alpheopsides); from A. paralpheopsides by the shape of the anterior margin of the orbital hoods and shorter major chela (see Coutière, 1905); from A. tenuipes by the presence of a subdistal tooth on the merus of the major cheliped, as well as color pattern (see comparison photos); and from the poorly known A. mitis by the relatively longer and more slender major chela. |
| Size | Body length to about 18 mm. |
| Color Pattern | See photo EA or WA. |
| Molecular Barcode | GenBank number AF321356, AF321357. |
| Remarks | The taxonomic identity of A. paracrinitus is problematical due to the presence of at least five genetically distinct cryptic species in the Atlantic Ocean, all three having similar color patterns; three of them lack spots on the abdomen and are very closely related to A. paracrinitus; the remaining two species are closer to A. rostratus. The problem is further complicated by two nominal species, A. ascensionis from the central Atlantic and A. togatus from the western Atlantic, that were placed in synonymy of A. paracrinitus, and by the presence of at least three species in the Indo-West Pacific region (besides A. bengalensis also A. aff. paracrinitus = sensu Coutière, 1905 and A. aff. rostratus). Most identifications of A. paracrinitus in the Indo-West Pacific (e.g., Banner and Banner, 1982, as A. paracrinitus and A. mitis) are erroneous. Notewiorthy, in at least some Indo-West Pacific taxa, the fingers of the minor chelae bear balaeniceps setae, a feature never found in the Atlantic and eastern Pacific specimens. |
| Major References | Miers, 1881b [original description and illustrations]; Ortmann, 1893 [description of A. ascensionis]; Armstrong, 1940 [description of Crangon togatus]; Chace, 1962 [records, taxonomic notes]; Crosnier and Forest, 1966 [records in E Atlantic, description, new figures, synonymy]; Hendrix, 1971 [records in Florida, figures,]; Chace, 1972 [records in W Atlantic]; Banner and Banner, 1982 [erroneous synonymy conclusions]; Manning and Chace, 1990 [record form Ascension]; Knowlton and Mills, 1992 [recognition of cryptic species based on color patterns]; Knowlton et al., 1993 [confirmation of cryptic species based on behavioral and molecular studies]; Christoffersen, 1998 [records in Brazil]; Williams et al., 2001 [recognition of further cryptic species in W and E Atlantic based on DNA studies]; Anker et al, in prep. [precision of taxonomic status, photos, revision of A. paracrinitus complex]. |