Fenneralpheus orabovis, Anker, Arthur, 2011

Anker, Arthur, 2011, Six new species and three new records of infaunal alpheid shrimps from the genera Leptalpheus Williams, 1965 and Fenneralpheus Felder & Manning, 1986 (Crustacea, Decapoda), Zootaxa 3041, pp. 1-38 : 32-35

publication ID	https://doi.org/ 10.5281/zenodo.278802
DOI	https://doi.org/10.5281/zenodo.4893594
persistent identifier	https://treatment.plazi.org/id/03BB87D5-FF8B-FFAA-FF7F-21CFFEE09A9A
treatment provided by	Plazi
scientific name	Fenneralpheus orabovis
status	sp. nov.

Treatment

Fenneralpheus orabovis View in CoL sp. nov.

Figs. 23–27 View FIGURE 23 View FIGURE 24 View FIGURE 25 View FIGURE 26 View FIGURE 27

Type material. Holotype: male (cl 8.2 mm), MNHN-IU-2011-5237, Panama, Caribbean coast, Bocas del Toro, Isla Bastimentos, near Bastimentos village, mudflat between mangrove stands, yabby pump, 0.2–0.5 m, leg. A. Anker, I. Marin, 0 3.05.2007 [fcn 07-163B1]. Paratype: 1 ov. female (cl 9.2 mm), RMNH D54557, same collection data [fcn 07-163B2].

Description. Frontal margin of carapace broadly rounded centrally, somewhat convex anterolaterally; pterygostomial angle not protruding anteriorly, rounded; cardiac notch very deep ( Fig. 23 View FIGURE 23 A–D). Sixth abdominal somite with large articulated plate ( Fig. 23 View FIGURE 23 E). Telson widest in proximal third, distinctly tapering distally; dorsal surface with one or two pairs of strong spiniform setae inserted in deep pits at some distance from lateral margin; posterior margin rounded, with two pairs of spiniform setae at posterolateral angles, lateral much more slender and shorter than mesial ( Fig. 23 View FIGURE 23 F, G).

Eyestalks with anteromesial margin bluntly projecting ( Fig. 23 View FIGURE 23 A). Antennular peduncles moderately stout, flattened dorsoventrally; stylocerite appressed, not exceeding distal margin of first article; ventromesial carina ending in small acute point and large rounded convexity, latter reaching beyond acute point; second article almost twice as long as wide; lateral flagellum with short secondary ramus ( Fig. 23 View FIGURE 23 A, B, H). Antenna with stout basicerite armed with sharp distoventral tooth; scaphocerite elongate, ovate, with small, subacute distolateral tooth reaching slightly beyond anterior margin of blade; carpocerite stout, overreaching scaphocerite and reaching slightly beyond end of antennular peduncle ( Fig. 23 View FIGURE 23 A, B). Mouthparts typical for genus, as illustrated ( Fig. 24 View FIGURE 24 A–E). Third maxilliped with lateral plate on coxa elongate, distally subacute, not reaching beyond arthrobranch ( Fig. 24 View FIGURE 24 F).

Major cheliped elongate, stout; basis with (female paratype) or without (male holotype) well-developed exopod; ischium stout, with smooth margins; merus robust, elongate, ventrally depressed, with smooth margins; carpus short, cup-shaped; chela elongate, with palm excavated ventrally, with smooth surface; fingers slender, about 0.6 palm length, twisted laterally, slightly curved, not gaping when closed, tips strongly crossing; finger cutting edges armed with several, widely spaced, strong teeth, diminishing in size distally; larger teeth with rounded distal surface minutely ridged on margins; adhesive disks feebly developed ( Fig. 25 View FIGURE 25 ). Minor cheliped with ischium unarmed; merus slender, ventrally depressed, ventrolateral margin ending in subacute tooth; carpus short, cupshaped; chela slender, simple, palm flattened mesially; fingers about as long as palm, tips crossing distally; cutting edges armed with widely spaced, small teeth, except on most distal portion ( Fig. 26 View FIGURE 26 A–C).

Second pereiopod slender, with merus shorter than carpus; carpus five-articulated, with article ratio approximately equal to 4.5: 1: 1: 1: 2 ( Fig. 26 View FIGURE 26 D). Third and fourth pereiopods similar; third pereiopod very stout, compressed; ischium unarmed or with small spiniform seta on ventrolateral surface; merus about 3.2 times as long as wide; carpus about 0.4 length of merus, with stout distoventral spiniform seta; propodus with one small and four large spiniform setae on ventral margin; dactylus about half length of propodus, slender, somewhat flattened on flexor margin, almost subspatulate, acute distally ( Fig. 26 View FIGURE 26 E–I). Fifth pereiopod much more slender than third or fourth, not compressed; propodus with seven setal rows distolaterally (26J, K).

Male second pleopod with appendix masculina exceeding appendix interna, with five stiff setae on apex and at least two more on outer margin ( Fig. 23 View FIGURE 23 I). Uropod with lateral lobe of protopod ending in two small, widely spaced teeth; exopod with truncate margin; diaeresis with very broad, feebly protruding lobe laterally, adjacent to spiniform seta, a large, blunt tooth lateral to deep mesial incision, and a large, sharp tooth at mesial margin ( Fig. 23 View FIGURE 23 J).

Size. The type specimens range from 8.2 mm cl (male) to 9.2 mm cl (female).

Colour in life. Pale reddish, due to numerous red chromatophores forming broad diffuse bands on the abdomen, antennular and antennal peduncles and telson with red chromatophores; in contrast, uropods and major and minor cheliped mostly colourless; major chela hyaline-white; walking legs also colourless ( Fig. 23 View FIGURE 23 ).

Etymology. Derived from the Latin translation of the type locality, Bocas del Toro, (ora bovis—bull’s mouth or boca del toro in Spanish); used as an adjective.

Type locality. Panama, Caribbean coast, Bocas del Toro.

Distribution. Western Atlantic: presently known only from the type locality on the Caribbean coast of Panama.

Ecology. Shallow mudflat near mangroves, in burrow of unknown host; several species from the genera Glypturus , Lepidophthalmus , Neocallichirus (Callianassidae) and Upogebia (Upogebiidae) were also collected at this site (A. Anker, pers. obs.; Dworschak & Anker, in study).

Remarks. Fenneralpheus orabovis sp. nov. differs from its only congener F. chacei by the pterygostomial angle not projecting anteriorly (vs. subacutely projecting in F. chacei ); the major chela fingers more slender and completely crossing when closed (vs. stouter and incompletely crossing in F. chacei ), and with the cutting edges armed with more widely spaced, distally rugose teeth (vs. armed with teeth closer to each other and bearing transverse-oblique ridges in F. chacei ); the presence of small adhesive disks on the major chela (absent in F. chacei ); the tooth on the ventromesial carina distally bearing a small acute point and a large convexity (vs. a very stout point and no convexity in F. chacei ); and the ischium of the fourth pereiopod with small spiniform seta on ventrolateral surface (vs. unarmed in F. chacei ) (cf. Figs. 20 View FIGURE 20 , 21 View FIGURE 21 , 23–26 View FIGURE 23 View FIGURE 24 View FIGURE 25 View FIGURE 26 ; see also Felder & Manning 1986, figs. 1– 3).

The presence of a well-developed exopod on the major cheliped of the female paratype of F. orabovis sp. nov. is highly unusual for the Alpheidae and therefore very intriguing. Rudimental exopod-like structures on the first pereiopods are known in several species of Athanas Leach, 1814 and some related genera (Anker et al. 2006). However, in the paratype of F. orabovis sp. nov., the exopod is long, reaching far beyond the distal margin of the ischium ( Fig. 25 View FIGURE 25 A, B), representing the only well-developed pereiopodal exopod presently known in the family Alpheidae (A. Anker, pers. obs.). Curiously, the minor cheliped of the female paratype and also both the major and the minor chelipeds of the male holotype show no trace of an exopod. With only two specimens, it is impossible to say whether an exopod is present only on the female major cheliped or whether its presence is inconsistent, i.e., it may be present or absent on either major or minor cheliped, and in either sex. For the time being, the presence of a well-developed exopod on the major cheliped (or chelipeds in general) cannot be treated as a specific feature of F. orabovis sp. nov. The two Panamanian specimens of F. chacei do not possess an exopod on neither major nor minor cheliped.