Processa hawaiensis ( Dana, 1852 )

Ayón-Parente, Manuel, Hendrick, Michel E. & Ríos-Jara, Eduardo, 2012, Notes on two species of Processa (Decapoda: Processidae) from the Mexican Pacific, Nauplius 20 (1), pp. 63-73 : 65-71

Processa hawaiensis ( Dana, 1852) ( Figs. 1-3 )

Nika hawaiensis Dana, 1852: 20 ; 1852a: 538; 1855, pl.33, fig. 7.- Weitenweber, 1854: 10.

Processa hawaiensis .- Rathbun, 1903: 912.- De Man, 1920: 199 (list).- Edmondson, 1935: 5.- Chace, 1962: 616. Hayashi, 1975: 106, figs. 22, 23a-j.- Álvarez et al., 1996: 721, fig. 5.

Processa paucirostris Edmondson, 1930: 3 , fig. 1; 1946: 248, fig. 148b.- Gurney, 1937: 87 (list).- Manning and Chace, 1971; 13 (list).

Processa hawaiiensis . - Manning and Chace, 1971: 13 (list).

Processa cf. aequimana .- Hendrickx and Wicksten, 2011: 31.

Material examined: Male, 2.7 mm, Isla Cocinas (ca 19°32’09”N, 105°05’09”W), Bahía de Chamela , Jalisco, Mexico, 5m, scuba diving, 26 June 2009 ( EMU- 9585 ) ; 2 males, 2.0- 2.2 mm, beach at Punta Mita, near village (20°47’20”N, 105°31’5”W), rocky intertidal, collected manually, 12 November 2004 ( EMU- 8834 ) ; 1 ovigerous female, 3.2 mm, Isla Cocinas (ca 19°32’09”N, 105°05’09”W), Bahía de Chamela , Jalisco, Mexico, 5m, scuba diving, 26 June 2009 ( EMU- 9586 ) ; 4 males, 1.8-2.2 mm, same locality ( EMU- 9587 ) ; 3 males, 2.5-2.7 mm, El Novillo, Bahía de Chamela , Jalisco, Mexico, 5 m, scuba diving, 28 November 2011 ( EMU- 9588 ) .

Description of Mexican material collected during this survey

Rostrum straight, short, reaching proximal one-third of ocular peduncles, ending in simple, acute spine with 2 subdistal very short setae, ventral margin convex ( Fig. 1B, C ). Carapace with lower orbital angle rounded, inconspicuous; antennal spine present; pterygostomialanglebroadly rounded.

Abdomen smooth ( Fig. 1A ). First to fourth pleura rounded. Fourth to sixth abdominal somites bearing short spiniform setae on dorsal and dorsolateral surfaces; fifth abdominal somite slightly shorter than sixth; pleura of fifth and sixth abdominal somites with posteroventral spine; fifth abdominal sternite ( Fig. 1D, E ) with a posteriorly curved spine.

Telson ( Fig. 1A, D, F, G ) about 1.7 times longer than sixth abdominal somite, length about 3 times greatest width; 2 pairs of dorsal and 3 pairs of distal spines, one pair of distal setae; anterior pair of dorsal spines of telson set at end of proximal third, posterior pair slightly beyond midlength; distance between anterior margin and anterior pair of spines about 1.3 times distance between pairs of dorsal spines; inner of distal spines shorter and plumose; dorsal surface with two irregular longitudinal rows of short spiniform setae; apex of telson produced into sharp projection.

Eye ( Fig. 1A, B ) moderately large; cornea width subequal to length of stalk and cornea combined, slightly more than 2 times greatest width of antennal scale.

Antennularpeduncle ( Fig. 1B ) extending beyond rostrumby distal 2 segments andabout 0.75 of proximal segment, latter longer than combined length of distal segments; proximal segment unarmed. Second segment sligthly shorter than third. Stylocerite ( Fig. 1H ) obtusely rounded laterally, unarmed, rounded distally. Dorsolateral flagellum of antennule as long as carapace; ventromesial flagellum about twice as long as carapace.

Antennal scale ( Fig. 1B, I ) extending to end of antennular peduncle, length of scale about 4 times longer than wide; distal spine of scale not overreaching blade. Antennal peduncle extending to middle of third segment of antennular peduncle. Basal segment of antenna lacking ventrolateral spine. Antennal flagellum about 5 times as long as carapace.

Third maxilliped ( Fig. 2G, H ) overreaching antennal scale by ultimate 2 segments; ultimate segment slightly longer than penultimate, apex acute; dorsomesial margin with 2 strong mobile spines, distal spineflankedby 4 smallerspines; mesial surface with short transverse rows of short bristles; dorsolateral margin with strong mobile spine on proximal fourth; lateral surface with edge of carina bearing row of small spines, posterior spines larger than others; penultimate segment with 2 mobile spines at dorsodistal margin, inner smaller; exopod rudimentary.

Mandible with 8-9 spines on posterior margin of molar process ( Fig. 2A, B ); Remaining mouthparts ( Fig. 2 C-F) similar to those figured by Manning and Chace (1971) for other species of Processa .

First pereopods with merocarpal articulation not extending beyond eye. Right first pereopod chelate ( Fig. 3A ); fingers about 0.75 length of palm; carpus shorter than palm; merus almost as long as carpus and chela combined. Left first pereopod ( Fig. 3B ) with simple dactyl, about 0.33 as long as propodus; carpus about 0.67 as long as propodus; merus almost as long as distal segments combined.

Second pereopods – asymetrical, right ( Fig. 3C ) longer than left, reaching distal third of antennal scale; merus with 7-9, and carpus with 17-19 articles; fingers as long as palm; carpus about 5 times as long as chela; merus 3 times as long as chela. Merus and carpus of left pereopod ( Fig. 3D ) with 5-7 and 11- 14 articles, respectively; fingers about 0.67 length of palm; carpus 4 times as long as chela; merus about 2.50 times as long as chela. Ischia of both pereopods bearing 2 to 3 indistinct articulations.

Third pereopod overreaching antennal scale by combined length of dactyl and propodus ( Fig. 3E ); dactylslender, simple, with apical setae; propodus 3 times as long as dactyl, unarmed, ornamented with scattered tufts of setae more numerous on ventral margin, longer tufts at apex; carpus 1.30 times as long as propodus, unarmed; merus as long as propodus, with a single subterminal spine on outer surface; ischium shorter than merus, unarmed.

Fourth pereopod overreaching antennal scale by dactyl, propodus, and 0.50 of carpus length; dactyl slender, simple, apex with tufts of setae ( Fig. 3F ); propodus about 3 times as long as dactyl, unarmed, with some scattered tufts of setae; carpus 1.25 times as long as propodus, unarmed, with scattered setae; merus about 1.20 times as long as propodus, unarmed, with scattered setae on ventral margin; ischium shorter than merus, unarmed; combined length of propodus and carpus of fourth pereopod greater than that of ischium and merus.

Fifth pereopod overreaching antennal scalebylengthofdactyl( Fig.3G );dactylslender, simple, with some apical setae; propodus about 3 times length of dactyl, provided with 9-12 spines on posterior margin; dorsal and ventral margins with scattered tufts of setae; carpus shorter than propodus, unarmed; merus as long as propodus, unarmed; ischium shorter than merus, unarmed; combined length of propodus and carpus slightly greater than that of ischium and merus.

Male endopod of first pleopod about 0.50 as long as exopod, tapering at apex ( Fig. 2J ). Appendix masculina ( Fig. 2I ) with 5 distal spines and 3 marginal spinules; appendix interna with 10 diminute distal coupling hooks.

Outer margin of uropodal exopod ending in triangular spine, flanked by longer mesial spine ( Fig. 1F ); with distinct suture. Endopodal upper surface with some short spiniform setae.

Ovigerous female with small and numerous eggs, 0.35 mm in diameter.

Color in life unknown.

Distribution in continental Mexico: Known from Isla Isabel (21°50’N, 105°54’W), Punta Mita, Nayarit (20°47’20”N - 105°31’5”W), and Bahía de Chamela (19°32’09”N - 105°05’09”W), Jalisco, Mexico ( Alvarez et al., 1996; this study).

Remarks: The fresh material from the Mexican Pacific examined herein differs in minor details from the description presented by Edmondson (1930) for P. paucirostris and from the redescription of P. hawaiensis by Hayashi (1975) ( Table 1 ). In our specimens, the rostrum is short, triangular and the apex is simple,with2 shortsubdistal setae. Edmondson (1930) described the rostrum as “shorter than eyes, straight, without keels, spines or hairs”. Hayashi (1975), who revised Edmondsońs (1930) type material and additional material of P. hawaiensis from the Pacific Ocean and East Africa, reported a short rostrum, triangular in dorsal view, with a simple apex. However, a reexamination of the material reported by Álvarez et al. (1996) indicates that the rostrum bears two short subdistal setae (J.L. Villalobos- Hiriart, pers. comm., March 2012).

The presence of a pair of setae (in addition to spines) on the posterior margin of telson was not reported by previous authors; however, presence of these in the material reported by Álvarez et al. (1996) was confirmed by J.L. Villalobos-Hiriart (pers. comm., March 2012). The number of articulations on the right and left carpus and merus of second pereopods seems to vary considerably (right: 15 to 18 and 7 to 9, respectively; left: 10 to 14 and 4 to 7, respectively; Table 1), but this is to be expected within the genus. Although it seems unlikely, Edmondson (1935: 5) reported an equal number of articulations (11) in both the right and left carpi of the second pereopods. Hayashi (1975) indicated that the ischium of third pereopod usually bears a single spine on proximal third, but he also observed three specimens lacking that spine. In all the specimens examined during this study, the ischium was always unarmed. The merus of the right cheliped in the material examined is about 2.5 times longer than carpus. Edmondson (1930) reported a cheliped merus twice as long as the carpus. According to Álvarez et al. (1996), the merus of the right cheliped is 2.2 to 2.6 times the length of carpus. In the case of the material examined, the propodus of fourth pereopod is 3 times as long as dactylus, and only 2 times as long in the type of P. paucirostris ( Edmondson, 1930) . Álvarez et al. (1996) also indicated that the propodus of the fourth pair of pereopods is more than three times as long as the dactylus. Hayashi (1975) did not give proportions between the propodus and dactyl of third to fifth pereopod. However, based on one of the illustrations he provided, the relationship between propodus and dactyl of pereopods 3-5 is less than 3 to 1. In the examined material, the first pair of pleopods bear long, plumose setae on both the outer and inner margins, and the apex is tapering, while in the material reported by Hayashi (1975) the apex is broad and the inner margin bears short (apparently non-plumose) setae.

Although these small differences might not be sufficient to justify recognition of a distinct species in the eastern Pacific, they seem to justify a thorough revision of material of P. hawaiensis throughout its currently recognized distribution range, including an analysis of their relationships based on molecular data.

Figures

Figure 1. Processa hawaiensis, male 2.7 mm (EMU-9585). (A) Lateral view; (B) Anterior region of carapace and cephalic appendages, dorsal view; (C) Rostrum, lateral view; (D) Abdominal somites 5-6, telson and right uropods, lateral view; (E) Detail of abdominal sternite 5, lateral view; (F) Sixth abdominal somite, telson and right uropods, dorsal view; (G) Magnification of the telson; (H) Details of stylocerites, removed, dorsal view; (I) Right antenna, dorsal view. Scale bars, 1 mm.

Figure 2. Processa hawaiensis, male 2.7 mm (EMU-9585). (A) Left mandible; (B) Right mandible; (C) Left maxillule; (D) Left maxilla; (E) Left first maxilliped; (F) Left second maxilliped; (G) Left third maxilliped; (H) Dactyl and propodus, left third maxilliped; (I) Endopod of right first pleopod; (J) Right second pleopod. Scale bars: A, B, I, 0.25 mm; C-H, J, 0.5 mm.

Figure 3. Processa hawaiensis, male 2.7 mm (EMU-9585). (A) Right first pereopod; (B) Left first pereopod; (C) Right second pereopod; (D) Left second pereopod; (E) Right third pereopod; (F) Right fourth pereopod; (G) Right fifth pereopod. Scale bar, 1 mm.

Tables

Table 1. Characters used in the original description and previous redescriptions of P. hawaiensis, and comparison with observations made using fresh material collected in Pacific western Mexico. ND, no data.

Characters	Edmondson (1930)	Hayashi (1975)	Álvarez et al. (1996)	This study
Rostrum	Short, straigth, without keels, spines or hairs	Short, triangular in dorsal view; apex simple	Short, triangular in dorsal view, with 2 short subdistal setae; apex simple	Short, triangular in dorsal view, with 2 short subdistal setae; apex simple
Posterior margin of telson	Three spines	Three pairs of spines	ND	Three pair of spines and one pair of setae
Rigth carpus of second pereopod	18 articulations	15 to 18 articulations	19 articulations	17 to 19 articulations
Right merus of second pereopod	8 articulations	7 to 9 ariculations	8 articulations	7 to 9 articulations
Left carpus of second pereopod	ND	10 to 14 articulations	12 articulations	11 to 14 articulations
Leftt merus of second pereopod	ND	4 to 7 articulations	7 articulations	5 to 7 articulations
Ischium of second pereopod	ND	Divided in 2 articulations	ND	Divided in 2 to 3 indistinct articulations
Ischium of third pereopod	ND	Usually with a single spine on proximal third of posterior margin	ND	Unarmed
Length proportion of merus/carpus of right cheliped	2 times carpus length	ND	2.2 to 2.6 times carpus length	About 2.5 times carpus length
Length proportion of propodus/ dactylus of fourth pereopod	2 times dactylus length	About 3 times dactylus length	More than 3 times dactylus length	About 3 times dactylus length
Propodus of fifth pereopod	ND	Provided with 9-12 spines on posterior margin	ND	Provided with 9-12 spines on posterior margin
Endopod of first male pleopod	ND	Broadened at apex; outer margin with long, plumose setae; inner margin with short setae	ND	Tapering at apex; outer and inner margins with long, plumose setae