Latreillopsis okala, Castro & Naruse, 2014

Castro, Peter & Naruse, Tohru, 2014, New species of Latreillopsis Henderson, 1888 (Brachyura: Homolidae) and Neopalicus Moosa & Serène, 1981 (Brachyura: Palicidae) from the Hawaiian Islands, Zootaxa 3764 (2), pp. 169-180 : 170-175

Latreillopsis okala n. sp.

( Figs. 1–3 )

“ Homola (Parhomola) majora ?” — Edmondson 1951: 202, fig. 10.

“? Latreillopsis aff. cornuta ” — Guinot & Richer de Forges 1995: 414.

“ (?) Latreillopsis cornuta ” — Castro 2011: 35 [in list].

Material examined. Holotype male 6.0 mm [5.4 mm not including rostrum] × 4.0 mm, off southwestern Maui , dredged, 91 m (300 ft), Mike Severns & Shirley Speer coll., 26.10.2112 ( USNM 1220315 ).

Description of male holotype. Carapace ( Fig. 1 , 3a ) longitudinally rectangular, longer than wide (cl/cw = 1.5, cl [not including rostrum]/cw = 1.3); small size; dorsal regions strongly defined, granular. Mesogastric region elevated, surmounted by large median boss, 2 protogastric bosses. Cardiac region with high, wide boss. Anterior branchial region slightly inflated, with blunt tubercle. Subhepatic region ( Fig. 3b ) slightly inflated, with 3 teeth, anterior tooth strongest, anteriorly directed; second, third teeth small, laterally directed. Rostrum proportionally short, straight. Pseudorostral spines long, curved, slightly longer than rostrum, outer margins with several rounded tubercles plus short, tooth-like tubercle near base of spine. Posterolateral border with 2 small, truncate teeth, better developed on left side.

Antennular, antennal articles bordered by short, rounded granules. Ocular peduncles (basophthalmite) long, thin, bordered by short, rounded granules; podophthalmite broad, bordered by few rounded granules. Cornea of eyes proportionally large, well developed.

Third maxilliped ( Fig. 3b ) merus with large, rounded anterior tubercle, sharp but not pointed anteroexternal angle; ischium narrow, about as long as merus, smooth except few short granules.

Chelipeds (P1) ( Fig. 2 ) long, slender, conspicuous rounded granules, spatulate setae along margins of all articles; large triangular tooth on proximal margin of left dactylus; large dark spot proximal to pollex; propodus enlarged distally; merus slightly larger than other articles, spines absent.

Ambulatory legs (P2, P3 missing in holotype) ( Fig. 1 ) P4 merus longer, wider than other articles, conspicuous rounded granules along margins of all articles; dorsally-oriented distal tooth on merus; dactyli with row of sharp spines on ventral margins. P5 reaching base of pseudorostral spine when folded; with conspicuous rounded granules along margins of merus, carpus; propodus slightly curved, with short granules only on dorsal margin; 2 long, acute, at tandem, proximal teeth; 2 small, parallel, acute teeth distal to large teeth; dactylus smooth.

Male abdomen ( Fig. 2a ) wide, all 6 somites freely articulating plus telson; homoloid press-button system, with prominence on abdominal sternite 4 locking with socket on abdominal somite 6. G1 ( Fig. 3c ) triangular, with short basal part, tapering distally; lateral margin slightly rimmed in ventral view, mesial part folded onto ventral surface over proximal three-fourths of triangular part. G2 ( Fig. 3d ) with truncated distal part, U-shaped in cross-section ̇

Complete abdomen (somite 6, telson in Edmondson 1951: fig. 10).

Female unknown.

Color. A photograph of the live holotype ( Fig. 1b ) shows bright orange carapace and eyes, orange-brown pereopods.

Etymology. From ̍ ōkala, Hawaiian for “rough” or “coarse,” in reference to the granular carapace and pereopods diagnostic for the new species. The name is treated as a Latin noun in apposition.

Remarks. Edmondson (1951: 203) examined two small specimens (female cl 8 mm, second female specimen “of about the same size”) dredged from 120 ft (36.6 m) off O‘ahu, Hawai‘i, and identified them as “probable juveniles of Homola (Parhomola) majora Kubo, 1936 ” (type locality: Japan). Serène & Lohavanijaya (1973: 31) believed that Edmondson’s specimens, which they did not examine, were not juveniles and that they “belonged probably to Latreillopsis but to laciniata more than to bispinosa .” Guinot & Richer de Forges (1995: 414) did not examine Edmondson’s specimens either and questionably identified them as “? Latreillopsis aff. cornuta . ” Latreillopsis cornuta Guinot & Richer de Forges, 1995 , was described from an ovigerous female (13 × 9.2 mm) from the Macclesfield Bank, South China Sea. Gordon (1950) also examined this specimen (as L. laciniata ) and figured the posterior half of the thoracic sternum ( Gordon 1950: fig. 26A). Castro (2011: 35) could not locate Edmondson’s specimens originally deposited in the Bishop Museum, Honolulu, Hawai‘i (catalog number 5530; Edmondson 1951: 202) and followed Guinot & Richer de Forges’ (1995) revision by listing Edmondson’s record as “(?) Latreillopsis cornuta . ”

The similarities between Edmondson’s specimens, based on his description and rather stylized drawings ( Edmondson 1951: 202, fig. 10), and L. okala n. sp. are evident from the general morphology of the dorsal surface of the carapace, posterior portion of the abdomen, and P1, P2, and P5, all of which were illustrated by Edmondson. The surface of the carapace and appendages were furthermore described as “densely covered with flat, wartlike granules” ( Edmondson 1951: 202), which is diagnostic of the new species. There are some differences, however. The slender teeth on the dorsal regions and outer margins of the carapace and on the pseudorostral spines ( Edmondson 1951: fig. 10a, b) are more blunt and thick in the holotype of the new species ( Fig. 1 , 3a ). The two small teeth just anterior to the posterior margin shown in Edmondson’s figure ( Edmondson 1951: fig. 10a) are absent in the holotype. The rostrum is slightly shorter than the pseudorostral spines in Edmondson’s figure but much shorter than the pseudorostral spines in the holotype of the new species. The rostrum and pseudorstral spines are cut off in the holotype, however, so the actual size relation cannot be ascertained. The pseudorostral spines, also incomplete, are slightly less curved in the holotype. These differences can perhaps be explained by differences in size, Edmondson’s specimens (cl 8 mm, not including the rostrum) being larger than the holotype (cl 5.4 mm, not including the rostrum). The right cheliped of the female illustrated by Edmondson (1951: fig. 10c), is more slender than in the male holotype ( Figs. 1 , 2 ), but the discrepancy is most probably the result of a sex difference. We are therefore confident that the holotype of the new species and Edmondson’s two specimens are conspecific.

There are superficial similarities between L. okala n. sp. and the description and photographs of L. cornuta given by Guinot & Richer de Forges (1995). As noted by Guinot & Richer de Forges (1995: 415), however, there are differences between L. cornuta and Edmondson’s (1951) specimens, which are now identified as belonging to the new species. The rostrum is shorter in L. cornuta ( Guinot & Richer de Forges 1995: fig. 37e) than in Edmondson’s specimens, there are four equidistant spinules on the P2–P4 meri of L. cornuta (smooth in Edmondson’s specimens), and four teeth on the subhepatic region, including two salient ones (three teeth, including a salient one in Edmondson’s specimens). They also mentioned as an additional difference the absence or near absence of “tubercles” on the dorsal surface of Edmondson’s specimens. This is an error because Edmondson (1951: 202) described the carapace of his specimens as covered with granules, a character they share with the holotype of the new species (see above).

The preceding differences between L. cornuta and Edmondson’s specimens (i.e. L okala n. sp.) are also observed when the description and illustrations of L. cornuta are compared with the holotype of the new species: rostrum that is shorter in L. cornuta ( Guinot & Richer de Forges 1995: figs. 37e, f, 41C) than in the new species ( Fig. 3a ), P2–P4 meri bordered by spines ( Guinot & Richer de Forges 1995: figs. 37e) but unarmed ( Fig. 1 ) in the new species, and four subhepatic teeth ( Guinot & Richer de Forges 1995: figs. 37e, f, 41C) instead of three in the new species ( Fig. 3b ). Other differences are also evident. The third maxilliped merus of the new species has a large, rounded tubercle on its anterior half ( Fig. 3b ) in contrast with two well-developed but smaller tubercles, one anterior and a second on the posterior half, in L. cornuta ( Guinot & Richer de Forges 1995: fig. 41C), and the carapace is granular ( Fig. 3a ) in contrast to the absence of conspicuous granules in L. cornuta ( Guinot & Richer de Forges 1995: fig. 41C). Although the adult male holotype of L. okala n. sp., is less than half (6.0 × 4.0 mm) that of the holotype of L. cornuta (13 × 9.2 mm), these morphological differences are regarded as not to be related to size, notwithstanding the scarcity of material.

Latreillopsis okala n. sp. shares with the nine previously described species of Latreillopsis (see Ng et al. 2008: 9), a well-developed sub-hepatic region of the carapace, sculpted dorsal surface of the carapace, small lateral carapace teeth, absence of supraorbital teeth, subcheliform P5, moderately long pseudorostral spines without welldeveloped teeth, and reduced chelipeds that are shorter than the ambulatory legs. Having a small size can be added to the characters shared with Latreillopsis , as re-described by Guinot & Richer de Forges (1995: 393), even if only three small specimens of the new species are known. The small holotype of the new species is an adult, having fully chitinized G1 and G2.

The nine known species of Latreillopsis are: L. antennata Guinot & Richer de Forges, 1995 (Chesterfield Islands, New Caledonia), L. bispinosa Henderson, 1888 ( Japan, Philippines), L. cornuta Guinot & Richer de Forges, 1995 (South China Sea), L. daviei Guinot & Richer de Forges, 1995 (Queensland, Australia), L. gracilipes Guinot & Richer de Forges, 1981 ( Vanuatu, New Caledonia), L. laciniata Sakai, 1936 ( Japan) , L. mariveneae Richer de Forges & Ng, 2007 ( Philippines) , L. tetraspinosa Dai & Chen, 1980 ( Japan to Solomon Islands), and L. trispinosa Richer de Forges & Ng, 2008 ( Philippines) . “ Latreillopsis aff . tetrapinosa ” ( Guinot & Richer de Forges 1995: 406, figs. 39g, 42B, 43B) from Durban, South Africa may represent a separate species.

Diagnostic for L. okala n. sp. is the presence of conspicuous tubercles on the carapace and pereopods ( Fig. 1 ) in contrast to the relatively smooth surface of congeners. The new species belongs to the group of four species of Latreillopsis having weakly-developed accessory teeth or spines on the pseudorostal spines (see Guinot & Richer de Forges 1995: 394). The new species differs from L. tetraspinosa by having three short subhepatic teeth ( Fig. 3b ), one rounded tubercle on the third maxilliped merus ( Fig. 3b ) and anterolateral margin of third maxillipeds merus that is sharp but not pointed ( Fig. 3b ), in contrast to four subhepatic teeth, 2 or 3 tubercles on the third maxilliped merus and ischium, and pointed, salient anterolateral margin of third maxillipeds merus in L. tetraspinosa ( Dai & Chen 1980: fig. 1; Guinot & Richer de Forges 1995: figs. 42C, D). The new species can be differentiated from L. bispinosa by having three short subhepatic teeth and a rostrum that is slightly shorter than the pseudorostral spines ( Fig. 3a, b ) in contrast with two long subhepatic teeth and pseudorostral spines that are much longer than the rostrum in L. bispinosa ( Henderson 1888: 22, pl. 2, fig. 3; Guinot & Richer de Forges 1995: figs.35a, b, 41B, 42A, A1), and from L. gracilipes and L. daviei by not having the swollen subhepatic region and the conspicuous lateroposterior tooth of both species ( Davie & Short 1989: fig. 3A, as L. bispinosa , and Guinot & Richer de Forges 1995: figs. 34, 40a, b for L. daviei ; Guinot & Richer de Forges 1995: 38 b, and Richer de Forges & Ng 2008: fig. 23 for L. gracilipes ). Latreillopsis gracilipes is also characterized by having three subhepatic teeth and one “granule” ( Guinot & Richer de Forges 1995: 402). The new species can be differentiated from L. trispinosa by its three short subhepatic teeth, third maxilliped merus with a large, rounded anterior tubercle and sharp anteroexternal angle ( Fig. 3a, b ) in contrast to three conspicuously long subhepatic teeth and smooth third maxilliped merus with a rounded anteroexternal angle in L. trispinosa ( Guinot & Richer de Forges 1995: fig. 41A, as L. bispinosa forme trispinosa ). The anteroexternal angles of the third maxillipeds in the specimens photographed by Richer de Forges & Ng (2008: figs. 24C, 25C), however, are sharp but the angle was described as rounded by Guinot & Richer de Forges (1995: 399). Furthermore, the ocular peduncle, described as short (“ beaucoup plus courts que chez L. tetraspinosa ”) by Guinot & Richer de Forges (1995: 399, fig. 41A, as L. bispinosa forme trispinosa ) is clearly longer in the specimens photographed by Richer de Forges & Ng (2008: figs. 24, 25).

There is limited information on the morphology of the G1 and G2 among the species of Latreillopsis . The G1 of L. okala n. sp. is triangular ( Fig. 3c ), but straight, with rounded apex in L. gracilipes ( Guinot & Richer de Forges 1981: fig. 6C) and L. daviei ( Davie & Short 1989: fig. 2a, as L. bispinosa ). The G2, with a truncated distal part that is folded in cross section ( Fig. 3d ), is similar to the G2 of L. daviei ( Davie & Short 1989: fig. 2b, as L. bispinosa ), but different from the slightly curved and rounded distal part of the G2 of L. gracilipes ( Guinot & Richer de Forges 1981: fig. 6C1).

Latreillopsis okala n. sp. is the fifth species of Homolidae reliably known from the Hawaiian Islands (see Castro 2011: 9, 34).

Figures

FIGURE 1. Latreillopsis okala n. sp. Holotype male 6.0 mm × 4.0 mm (USNM 1220315): a, habitus, dorsal view; b, color in life (photograph by P. Fiene).

FIGURE 2. Latreillopsis okala n. sp. species. Holotype male 6.0 mm × 4.0 mm (USNM 1220315): a, cephalothorax, ventral view; b, outer surface of propodus and dactylus, outer view.

FIGURE 3. Latreillopsis okala n. sp. Holotype male 6.0 mm × 4.0 mm (USNM 1220315): a, cephalothorax, dorsal view (wartlike granules are not drawn); b, left anterior part of ventral surface of cephalothorax (wart-like granules are not drawn); c, left G1, ventral view; d, left G2, ventral view. Scales: a–d = 1 mm.