Neopalicus halihali, 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 : 175-179

Neopalicus halihali n. sp.

( Figs. 4 , 5 )

Holotype. Ovigerous female, 5.5 mm × 6.2 mm, off southwestern Maui, dredged, 91 m (300 ft), Mike Severns & Shirley Speer coll., 26.10.2112 ( USNM 121140 ).

Description of female holotype. Carapace subquadrate ( Figs. 4 , 5a ), slightly wider than long (cl/cw = 0.9); small size; dorsal surface covered with fine granules; horizontal row of 6 large, low, granular bosses across carapace posterior to conspicuously elevated mesogastric region; bosses with numerous short plumose setae. Confluence of branchial, mesogastric regions depressed; depression along median portion of frontal region. Short, bilobed rostrum. Frontal border of carapace lateral to rostrum with single, rounded frontal lobe slightly salient anteriorly. Margin between frontal lobes, supraorbital border sinuous, ending in sharp angle, forming deep Vshaped fissure before supraorbital border. Supraorbital border with 2 rounded lobes (right outer lobe missing), inner lobe slightly larger than outer lobe. Postorbital angles short, rounded, not extending beyond dorsal border of retracted eye peduncle, nearly straight. Anterolateral border of carapace ( Fig. 5a ) with 3 large, salient, triangular teeth with acute tips, plus short, blunt fourth teeth; teeth decrease in size posteriorly, first (anteriormost) largest, most conspicuous. Posterior border with row of short, elongated tubercles, few plumose setae; 2 rows of rounded tubercles anterior to border.

Basal antennal article ( Fig. 5b ) slender, rectangular, with wide, long, wing-like extension on outer margin; flagellum long, with few short, simple setae. Epistome dorso-ventrally expanded, forming broad, semicircular, nearly flat median lobe; 2 acute teeth on median margin. Ocular peduncle (basophthalmite) ( Fig. 5b ) thick, with 3 dorsal, triangular, crest-like tubercles, median tubercle largest, rounded tubercle on distal extension of peduncle nearly encircled by cornea. Cornea dorso-ventrally depressed, wider than base of ocular peduncle.

Suborbital border ( Fig. 5b ) with 2 lobes; short, rounded inner lobe, wider, slightly convex, rounded outer lobe with microscopically dented margin. Pterygostomial lobes projecting ventrally, forming flat, rounded structure posterior to inner suborbital lobe.

Inner margins of third maxilliped ischium straight; surface granular, upper margin rounded. Merus much narrower than ischium, straight-edged.

Chelipeds (P1) ( Fig. 4 ) slightly unequal; propodus of larger cheliped slightly higher, thicker than smaller cheliped, few plumose setae. Dorsal, outer margin of cheliped propodus with crest having 2 high, rounded tubercles plus several smaller tubercles, denticles; inner surface bare of setae; fingers slender, with cutting edges or rounded teeth. Carpus short, dorsal, outer margin with conspicuous, high, rounded tubercle; merus slender, smooth.

Ambulatory legs (P2–P4) ( Figs. 4a , 5c ) dorsoventrally flattened; P2 shorter than P3, P4; P3 nearly as long as P4. Upper, lower margins of P3, P4 meri with several short, tooth-like tubercles; distalmost upper margins angular, without distinctive tubercle. Outer margins of P3, P4 carpi with 2 or 3 triangular, tooth-like tubercles, distalmost largest. Outer margins of P3, P4 propodi smooth, inner margins armed with 6 or 7 short teeth, low carina along middle portion. P3, P4 dactyli ( Fig. 5c ) with long, inner margins armed with 5 or 6 short teeth, low carina along middle portion. Few long plumose setae on inner, outer margins of P2–P4 meri, distal portion of carpi; numerous long plumose setae on inner surface of propodi, dactyli. P5 ( Fig. 4 ) reduced (0.8 cl), dorsal to P4; merus slender, with microscopic tubercles along inner margin, scattered plumose setae; propodus with 3 long spines along inner margin; dactylus with microscopic tubercles along margins, acuminate tip.

Abdomen with all somites freely articulating, outer surface smooth without transversal ridges. Vulva small, on thoracic sternite 6 but displaced to median plate of sternum.

Male unknown.

Etymology. Reduplication for emphasis of hali, Hawaiian for “to transport,” in reference to the carrying behavior recorded in the new species. The name is treated as a Latin noun in apposition.

Remarks. Neopalicus halihali n. sp. is assigned to Neopalicus Moosa & Serène, 1981 , as re-described by Castro (2000: 548). Neopalicus until now consisted of three Indo-West Pacific species: N. contractus (Rathbun, 1902) , N. jukesii (White, 1847) , and N. simulus Castro, 2010 . The new species shares with its congeners a subquadrate carapace with horizontal rows of large and low bosses on its dorsal surface; large, spherical (not rheniform) eyes with ocular peduncles each having three dorsal tubercles, supraorbital borders with two rounded lobes; basal antennal article with a flattened expansion; dorso-ventrally flattened, expanded epistome, without an apparent median fissure; P2–P4 with dorso-ventrally flattened (not filiform) carpi, propodi, and dactyli; spinous posterior margins of the P5 propodus; and abdomen of adult females with all somites freely articulating (see Castro 2000: 548, tab. 1).

There are nevertheless differences between N. halihali n. sp. and its three congeners: presence of three triangular teeth along each anterolateral border ( Fig. 5a ) instead of two large truncated teeth ( Castro 2000: fig. 39; 2010: fig. 1A, B), presence of a small fourth anterolateral tooth absent in congeners, P3 and P4 propodi with simple margins ( Fig. 4a ) without a wide and convex extension ( Castro 2000: fig. 39; 2010: fig. 1A, B), P2 and P3 dactyli posterior margins dentate ( Fig. 5c ) instead of entire, and female abdomen with smooth somites instead of the presence of ridges. The rostrum is bilobed as in N. contractus and N. jukesii ( Castro 2000: fig. 39) but different from the simple rostrum of N. simulus (Castro 2010: fig. 1A, B). The suborbital border consists of two slightly convex lobes ( Fig. 5b ), similar to N. simulus (Castro 2010: fig 1C), but different from the triangular lobes of the other two congeners ( Castro 2000: fig. 40).

Neopalicus halihali n. sp. is closest to N. simulus , another small-size species known only from French Polynesia. In addition to the similarities and differences indicated above, the new species differs from N. simulus by having a row of low, elongated tubercles on the posterior border of the carapace ( Fig. 5a ) (short, rounded tubercles, one at each end, plus three median tubercles in N. simulus ); basal antennal article with wide, long outer extension ( Fig. 5b ) (short, wing-like extension in N. simulus ; Castro 2010: fig. 1C); outer margin of cheliped propodus with a conspicuous crest consisting of two high, rounded tubercles plus several smaller tubercles and denticles ( Fig. 4a ) (two high, rounded tubercles and no crest in N. simulus ; Castro 2010: fig. 1A); dorsal, outer margin of cheliped carpus with a conspicuous, high, rounded tubercle ( Fig. 4a ) (smooth in N. simulus ; Castro 2010: fig. 1A); outer margins of P3 and P4 carpi with tooth-like tubercles and denticles ( Fig. 4a ), inner margin dentate (outer margin with rounded tubercles, smooth inner margin in N. simulus ; Castro 2010: fig. 1A); outer margins of P4 propodi with microscopic tubercles (entire, with wide, convex, carina-like extension in N. simulus ); inner margins of P3 and P4 dactyli dentate ( Fig. 5c ) (entire in N. simulus ; Castro 2010: fig. 1A); and smooth female abdomen, without transversal ridges (transversal ridge along each somite 1–4, less pronounced in other somites in N. simulus ).

The male of the new species remains unknown. Males of the three congeners are characterized by having elongated abdomens with all somites freely articulating, and a long and slender G1 with sinuous basal portion but very different terminal portions (see Castro 2000: fig. 41a–c for N. contractus and N. jukesii ; 2010: fig. 1D for N. simulus ). Although some of the differences between the chelipeds of the new species and N. simulus may be sex related, the characters of the female holotype alone are distinctive enough to warrant its description as a separate species of Neopalicus .

Neopalicus contractus is known from across the Indian (type locality: Maldives) and western Pacific oceans ( Philippines to New Caledonia and the Marshall Islands). The distribution of N. jukesii (type locality: Queensland, Australia) is close to that of N. contractus except that N. jukesii is also known from the Red Sea and Japan but not from the central Pacific ( Castro 2000: fig. 49, 588). Both N. simulus and N. halihali n. sp. are known only from the eastern limits of the Indo-West Pacific region, N. simulus from the Austral Islands, French Polynesia, and N. halihali n. sp. from the Hawaiian Islands. Neopalicus contractus and N. jukesii have been collected, sometimes sympatrically, in coarse sand near coral reefs at depths of 10–146 m (see Castro 2000: 587), N. simulus from rocky bottoms containing coral rubble at 90–200 m (one specimen from 360–840 m; Castro 2010: 78), and N. halihali n. sp. from coral rubble at 91 m.

The live holotype of the new species was photographed carrying what appears to be a dead fragment of a filamentous red alga ( Fig. 4b ). Two other species of palicids have been recorded as carrying fragments of sediment or seaweeds with their reduced, dorsally-placed P5, a behavior known as carrying behavior (see Guinot et al. 2013: 246, fig. 54). This behaviour is most probably widespread, even universal, among palicids.

The new species represents the fourth species of Palicidae known from the Hawaiian Islands (see Castro 2011: 10, 54).

Figures

FIGURE 4. Neopalicus halihali n. sp. Holotype female 5.5 mm × 6.2 mm (USNM 121140): a, habitus, dorsal view; b, color in life, carrying fragment of alga (photograph by P. Fiene).

FIGURE 5. Neopalicus halihali n. sp. Holotype female 5.5 mm × 6.2 mm (USNM 121140): a, right half cephalothorax; b, right half of orbit, anteroventral view; c, dactylus of P4, left, ventral view. Scales: a–c = 1 mm.