Alpheus millsae, Anker & Hurt & Knowlton, 2007

Anker, Arthur, Hurt, Carla & Knowlton, Nancy, 2007, Revision of the Alpheus nuttingi (Schmitt) species complex (Crustacea: Decapoda: Alpheidae), with description of a new species from the tropical eastern Pacific, Zootaxa 1577 (1), pp. 41-60 : 50-55

publication ID	https://doi.org/ 10.11646/zootaxa.1577.1.5
publication LSID	lsid:zoobank.org:pub:2DF6B6E7-0509-4D92-8DD6-96768B2BBE93
persistent identifier	https://treatment.plazi.org/id/039787DD-221C-2803-BEDF-F93CFF48FE31
treatment provided by	Felipe
scientific name	Alpheus millsae
status	sp. nov.

Treatment

Alpheus millsae View in CoL , n. sp.

Figs. 3 View FIGURE 3 , 4 View FIGURE 4 , 5C View FIGURE 5 , 6C View FIGURE 6 , 7G–H View FIGURE 7 , 8C View FIGURE 8

Alpheus canalis View in CoL sp-b— Knowlton & Mills, 1992: 2.

Alpheus canalis View in CoL sp. b— Knowlton et al., 1993: 1630.

Alpheus canalis View in CoL “blue”—Williams et al., 2001: 377.

Alpheus canalis “blue antennae”—Williams et al., 2001: 385. Material examined.— 1 male, holotype, CL 13.7 mm, USNM 1100686 About USNM , Panama, Panama City, off Casco Viejo , rocky intertidal, near extreme low tide mark, under rocks on coarse sand, coll. A. Anker, C. Hurt, J. Jara and E. Tóth, 30 Mar 2006 [fcn 06-343]; 1 male, 1 ovig. female, paratypes, USNM 1100687 About USNM , same collection data as for holotype [fcn 06-346] ; 1 male, 1 ovig. female, paratypes, MNHN-Na 16369, same collection data as for holotype [fcn 06-345] ; 1 ovig. female, paratype, RMNH D 51746, same collection data as for holotype [fcn 06-344] ; 1 male, USNM 1100688 About USNM , Río Mar , rocky intertidal, under rocks, coll. N. Knowlton lab., 19–20 Feb 1992 [fcn B-112, C-391, dissected]; 1 ovig. female, USNM 1100689 About USNM , same collection data as previous specimen [fcn B-112, C-392] ; 1 female, 2 ovig. females, USNM 1100690 About USNM , Panama, Panama City, off Casco Viejo , rocky intertidal, under rocks, coll. N. Knowlton lab., Feb 1999 ; 1 male, 1 ovig. female, UP, Panama, Río Mar , under large rocks at low tide, coll. A. Anker, I. Marin and J. Jara, 19 Apr 2007 [fcn 07-121].

Description.—Carapace smooth, not setose, laterally not compressed. Rostrum moderately long, slender, subtriangular, horizontal or slightly ascendant ( Fig. 4B View FIGURE 4 ), subacute distally ( Fig. 4A, C View FIGURE 4 ), not reaching half length of first segment of antennular peduncle ( Fig. 4A View FIGURE 4 ); rostral carina sharply delimited between orbital hoods, broadening and becoming blunt posterior to orbital hoods, continuing as very flat, barely noticeable ridge to half length of carapace ( Fig. 4A, C View FIGURE 4 ); adrostral furrows deep, markedly (but not abruptly) delimited posteriorly ( Fig. 4A, C View FIGURE 4 ); orbito-rostral process rather feebly developed, with V-shaped median notch. Orbital hoods inflated, distally rounded, unarmed ( Fig. 4A, C View FIGURE 4 ), sloping gradually into adrostral furrows; margin between rostrum and orbital hoods not protruding. Pterygostomian angle broadly rounded, not protruding ( Fig. 4B View FIGURE 4 ); cardiac notch well developed. Eyes completely concealed in dorsal, lateral and frontal view. Ocellar beak dorsally projecting between eyes, fitting into V-shaped notch of the orbito-rostral process.

Antennular peduncles moderately slender, second segment slightly more than twice as long as first; stylocerite with acute tip, reaching to distal margin of segment ( Fig. 4A View FIGURE 4 ); mesioventral carina of first segment with tooth usually bearing small acute point ( Fig. 4D View FIGURE 4 ); lateral flagellum with numerous tufts of aesthetascs, secondary ramus rudimentary. Antenna with basicerite bearing strong, acute ventrolateral tooth ( Fig. 4B View FIGURE 4 ); carpocerite stout, reaching slightly beyond distolateral tooth of scaphocerite; scaphocerite not reaching distal margin of antennular peduncle ( Fig. 4A View FIGURE 4 ), distolateral tooth of scaphocerite reaching far beyond relatively narrow blade ( Fig. 4E View FIGURE 4 ), lateral margin slightly concave ( Fig. 4E View FIGURE 4 ).

Mouthparts (mandible, maxillule, maxilla, first and second maxillipeds) typical for Alpheus . Third maxilliped moderately stout ( Fig. 4F View FIGURE 4 ); lateral plate with blunt apex ( Fig. 4G View FIGURE 4 ); antepenultimate segment subtriangular in cross-section, lateral surface flattened, ventral margin straight; penultimate segment about twice as long as wide, distally widening; ultimate segment particularly setose, distally tapering ( Fig. 4F View FIGURE 4 ).

Male major cheliped ( Fig. 4I–J View FIGURE 4 , 5C View FIGURE 5 ) with short ischium and stout merus; merus about twice as long as proximally wide; ventral surface flattened; dorsal margin distally bluntly projecting ( Fig. 4I View FIGURE 4 ); ventromesial margin straight, distally with small blunt tooth ( Fig. 4H View FIGURE 4 ); carpus short, cup-shaped; chela ovate, laterally somewhat compressed; dorsal and ventral margins of palm with broad transversal grooves, dorsal groove about half as high as long, adjacent shoulder rounded, not overhanging groove, sloping with angle of about 80° into groove ( Fig. 4J View FIGURE 4 ); ventral groove broad, deep, oblique, adjacent shoulder rounded, not protruding, sloping with angle of about 90° into groove ( Fig. 4J View FIGURE 4 ); lateral surface of palm with deep longitudinal groove extending from dorsal groove to linea impressa ( Fig. 4I, J View FIGURE 4 ); deep oblique-transversal groove extending from ventral groove onto lateral surface ( Fig. 4 View FIGURE 4 , I, J); very shallow depression extending from pollex to area between longitudinal and oblique-transversal grooves ( Fig. 4J View FIGURE 4 ); mesial face with longitudinal groove extending from dorsal groove ventrally and posteriorly to below linea impressa ( Fig. 4H View FIGURE 4 ); deep oblique-transversal groove extending from ventral groove onto mesial surface; linea impressa well marked; adhesive disks small ( Fig. 4J View FIGURE 4 ); fingers about half-length of palm; pollex with mesiodorsal margin forming large blunt angle ( Fig. 4H View FIGURE 4 ), distally without ridge; dactylus reaching slightly beyond pollex, proximally with longitudinal ridge or crest on mesial face ( Fig. 4H–J View FIGURE 4 ); plunger moderately large, distally truncate ( Fig. 5C View FIGURE 5 ), with stamen-shaped sensillae. Female major cheliped similar to male major cheliped, but smaller and more slender, chela also with somewhat different proportions ( Fig. 4S View FIGURE 4 ).

Male minor cheliped ( Fig. 4K–M View FIGURE 4 ) with very short ischium; merus dorsally and ventrally somewhat inflated, about three times as long as wide proximally, ventromesial margin straight, distally blunt, without acute tooth; carpus cup-shaped, more elongated than carpus of major cheliped, distally with dorsomesial lobe ( Fig. 4K View FIGURE 4 ); chela with palm slightly longer than fingers ( Fig. 4M View FIGURE 4 , 6C View FIGURE 6 ), without sculpture, distomesial margin of palm with blunt tooth ( Fig. 4K, L View FIGURE 4 ), ventral margin slightly concave below base of pollex; linea impressa well marked; adhesive disks inconspicuous; fingers elongate, slender, about half of palm height, without rows of balaeniceps setae ( Fig. 4K–M View FIGURE 4 ), cutting edges sharp, blade-like, that of pollex proximally slightly convex ( Fig. 4M View FIGURE 4 ). Female minor cheliped similar, but with more slender fingers.

Second pereiopod ( Fig. 4N View FIGURE 4 ) slender; ischium subequal to merus; carpus five-segmented, first segment longest, ratio of carpal segments (from proximal to distal) approximately 5: 3: 1: 1: 2; chela as long as second segment, simple, with fingers equal to palm ( Fig. 4N View FIGURE 4 ). Third and fourth pereiopods similar in shape and length; third pereiopod with ischium ventrally without spine ( Fig. 4O View FIGURE 4 ); merus with unarmed distoventral margin, about four times as long as wide; carpus with unarmed ventral margin, more slender than merus; propodus armed with about 10 spines or pairs of spines on ventral margin, and two spines on distoventral margin ( Fig. 4P View FIGURE 4 ); dactylus simple, conical, gradually curved towards subacute tip, about one third length of propodus ( Fig. 4P View FIGURE 4 ). Fifth pereiopod smaller and more slender than third and fourth pereiopods; ischium ventrally unarmed; propodus ventrally with at least nine spines (including distoventral spine), distolaterally with numerous rows of grooming setae; dactylus simple, conical [see Fig. 1P View FIGURE 1 for almost identical fifth pereiopod in A. nuttingi ].

Abdominal segments with broadly rounded posteroventral margins; sixth segment without articulated flap, posterior margin straight, dorsolateral projections rounded; preanal plate rounded. Male second pleopod with appendix masculina subequal to appendix interna, apex furnished with at least eight stiff, elongated setae ( Fig. 4Q View FIGURE 4 ). Uropod with sympodite bearing distally two large subacute teeth; exopod with diaeresis bearing two large rounded lobes on lateral half ( Fig. 4R View FIGURE 4 ), distolateral spine moderately long, slender; distal margin of endopod with row of spinules ( Fig. 4R View FIGURE 4 ). Telson broad, tapering posteriorly; dorsal surface with median depression and two pairs of strong spines, situated far from lateral margins, anterior and posterior to telson mid-length, respectively ( Fig. 4R View FIGURE 4 ); posterior margin broadly rounded, with two pairs of small posterolateral spines, mesial longer than lateral, and row of spinules between mesial spines ( Fig. 4R View FIGURE 4 ); anal tubercles well developed. Gill/exopod formula typical for Alpheus .

Size.—The largest examined male is the holotype with 13.7 mm CL and 41.8 mm TL; the largest paratype female is 12 mm CL and 36.2 mm TL.

Color.—Body greenish-brown or greenish (combination of reddish and bluish chromatophores) speckled with numerous pale green or yellow dots or small yellowish spots, most of them isolated and not interconnecting; flanks of carapace whitish; legs reddish with some spots and white patches marking articulations; third and fourth abdominal somite with pair of minute dark dorsolateral spots; fifth somite with one minute brown mediodorsal spot; major and minor chelae mesially brown-greenish or olive-green with numerous irregular white spots and dots, most isolated, not interconnecting; pale orange areas marking palmar depressions; dactylus of major chela pink and white distally; antennular and antennal flagella pale blue or bluish-greenish ( Figs. 3 View FIGURE 3 , 7G, H View FIGURE 7 ); ovigerous females with olive-green eggs ( Fig. 8C View FIGURE 8 ).

Type locality.— Casco Viejo , Panama .

Distribution.—Eastern Pacific: presently known only from the Pacific coast of Panama, near Panama City (Amador, Casco Viejo) and Río Mar.

Ecology.— Alpheus millsae , n. sp. is ecologically similar to A. galapagensis , but appears to occur in slightly deeper water; all specimens were collected near extreme low tide mark on rocky shores, under rocks on coarse sand, locally also silt and various debris (shells, urchin tests etc.). Some specimens were found under rocks together with fire worms ( Amphinomidae ).

Remarks.— Alpheus millsae , n. sp. may be distinguished from its transisthmian sister species, A. nuttingi , and from the sympatric A. galapagensis , by the higher and posteriorly further extending rostral carina ( Figs. 4C View FIGURE 4 ) and shorter plunger of the dactylus on the major chela ( Fig. 5C View FIGURE 5 ); from A. nuttingi by the mostly non-interconnected pale-greenish dots (vs. interconnected in A. nuttingi ) (cf. Fig. 7 View FIGURE 7 ); from A. galapagensis by the absence of a small spine on the ischium of the third pereiopod ( Fig. 4O View FIGURE 4 ), which is always present in A. galapagensis ( Kim & Abele, 1988, fig. 30j), the more densely spaced, often irregular and interconnecting spots on the mesial face of the major claw (vs. less densely spaced, rounded spots in A. galapagensis ), and the bluish (vs. orange in A. galapagensis ) antennal and antennular flagella (cf. Fig. 7 View FIGURE 7 ) (see also Table 1).

The color of freshly laid eggs of A. millsae , n. sp. was not recorded; the developing eggs are dull olivegreen ( Fig. 8C View FIGURE 8 ). Thus it remains to be confirmed whether egg color in A. millsae , n. sp. can be used as a diagnostic character to distinguish it from A. galapagensis and A. nuttingi .

Etymology. —The species is named after DeEtta K. Mills, in recognition of her help in earlier studies of neotropical cryptic species of Alpheus .

GenBank number.— COI 5’ EF092283 View Materials (fcn 06-334); COI 3’ AF309881 View Materials (fcn 99-004), AF309882 View Materials (fcn 99-005) .