Babamunida kanaloa, Schnabel, Kareen E., Martin, Joel W. & Moffitt, Robert B., 2009

Schnabel, Kareen E., Martin, Joel W. & Moffitt, Robert B., 2009, Additions to the decapod crustacean fauna of the Hawaiian Islands, III. A new species of the genus Babamunida (Crustacea: Galatheidae) from Hawaii based on morphological and molecular evidence, Zootaxa 2130, pp. 21-30 : 23-28

Babamunida kanaloa n. sp.

( Figs. 1–3 )

Holotype. ♂ (18.2 mm cl., 25.7 mm incl. rostrum), French Frigate Shoals, Northwestern Hawaiian Islands, Pacific Ocean, 23°42.72'N, 166°21.12'W, 255– 236 m, baited trap, 23 October 2006, coll. J. Martin, K. Coontz, E. Soto, T. Lotufo ( LACM CR 2006-014.21).

Description of holotype. Carapace: 1.2 times as long as wide (1.7 including rostrum), shallowly convex from side to side. Dorsal surface moderately strigose, all but two striae interrupted. Anterior portion spinose and rugose; epigastric region with 3 pairs of strong spines and numerous smaller spines and granules; posterior gastric region rugose with small lateral spines; hepatic region covered with spines. One pair of prominent postcervical spines. Anterior branchial region with numerous small spines. Cardiac and posterior branchial regions unarmed except for 1 small spine near branchio-cardiac boundary (absent on right). Frontal margin strongly oblique, antennal and anterolateral spines present and subequal in size. Lateral margin slightly convex, with 3 branchial spines excluding anterolateral spine. Posterior margin unarmed; transverse ridge directly anterior to posterior margin. Rostrum spiniform, 0.4 times length of remaining carapace; dorsal surface carinate; lateral margins distally serrated; rostrum and supraocular spines separated by distinct groove.

Epistomal ridges: lateral ridges terminating at ventral margin of orbit.

Sternum: 1.2 times wider than long. Surface smooth. Sternite 3 bilobed, separated by median notch; lateral margins rounded. Sternite 4 2.3 times as wide as sternite 3, anterior margin steeply convex; surface with 1 pair of striae in anterior portion and 3 pairs of small spines (forming an inverse ‘V’) along posterior midline.

Abdomen: tergites smooth and unarmed, each with single median transverse stria on tergites 2–6; lateral portions with few short striae. Telson 1.7 times wider than long, composed of 9 incompletely separated plates and covered with short granulose ridges.

Eyes: cornea globular, smooth, 0.6 times length of ocular peduncle, overreaching supraocular spines and distal third of rostral spine. No eyelashes.

Antennule: moderately elongate; with 2 distal spines (subequal in length) and 2 lateral spines; median spine largest, overreaching distal spines. Lateral margin slightly granulate; surface otherwise smooth.

Antennal peduncle: articles 1–3 each with 2 distal spines; spines on article 2 largest, both reaching end of article 3; article 4 with 2 small distolateral spines.

Maxilliped 3: surface smooth; ischium with 2 distal spines, spine on flexor margin long and slender, spine on extensor margin small; crista dentata with 25 small teeth on entire ridge (1 on basis). Merus flexor margin with strong median and small distal spine; extensor margin irregular with small distal spine. Carpus, propodus and dactylus unarmed except for small distal blunt process on carpus; extensor margin of carpus irregular.

Pereopod 1 (cheliped): stout, spinose and entirely covered with small setiferous ridges; 3.8 times postorbital carapace length (2.7 times cl. including rostrum). Ischium unarmed. Merus with row of strong spines along distomesial margin, dorsal surface with scattered spines and a patch of dense setae along mesial surface, including scattered iridescent and plumose setae. Carpus and palm with rows of spines dorsally and row of large spines along mesial margins, interspersed with granules and small spines; length of carpus 0.4 times that of palm. Propodal palm 1.8 times as long as high. Fingers 1.5 times as long as palm; rows of spines laterally and dorsally; opposable margins strongly gaping proximally and with large, irregular granules.

Pereopods 2–4 (ambulatory legs 1–3): similar; slender, spinose margins and surfaces scattered with setiferous ridges. Merus 1.0–1.2 times as long as propodus (P4 shortest); extensor margin with 6–10 spines excluding distal spine (least on P4); flexor margin with 3–4 stout spines plus strong distal spine. Carpus with 4 spines on extensor margin; ventral margin irregular and with distal spine. Propodus about 10 times longer than wide; 1.7–1.9 times as long as dactylus; extensor margin spinose (7–9 large spines, interspersed with transverse rows of minute spines, detail figure 2M); flexor margin with 17–22 spines along entire margin (P4 least). Dactylus slender and straight; extensor margin with row of long simple setae and row of short plumose setae; flexor margin with 12 or 13 movable spines (excluding distal) along entire length, decreasing in size posteriorly, ultimate and penultimate most distantly spaced.

Live coloration: base colour pale orange to cream on carapace, cream or white on appendages. Carapace with bright red markings in gastric, cardiac and branchial regions and tips of spines. Rostrum light red along distal half. Supraocular spines almost entirely red. Abdominal segments with 1 entire band of red along anterior margins of segments just behind anterior segment border (which is white). Pereopod 1 with red spot distodorsally on carpus and with 2 dorsolateral patches on palm (median of which is star-shaped); fingers with 2 red bands on each finger. Pereopods P2–4 with red bands on meri, carpi and propodi. Antennal flagellum dark red along entire length.

Remarks. The morphological characteristics of the new species clearly distinguish the new species as belonging to the genus Babamunida :, the rostrum and supraocular spines are dorsally carinate with carinae reaching the anterior portion of the epigastric region, the grooves between the rostrum and supraocular spines are deep and continue well beyond the meniscus between the spines, and the lateral ridge of the epistome ends at the ventral margin of the orbit, between the antennular and antennal peduncles instead of ending laterally at the base of the basal antennal segment at level of the antennal gland aperture ( Cabezas et al. 2008).

Babamunida kanaloa n. sp. shares a number of distinct characters with each of its congeners, as follows. The strongly oblique anterior margin of the carapace with distinct antennal spine is similar to B. javieri and B. hystrix . The carapace ornamentation and striation are similar to those seen in B. brucei . In the arrangement and size of antennal spines, the new species is similar to B. hystrix . The shape and ornamentation of the third maxilliped are very similar to what is seen in B. plexaura . In body size B. kanaloa matches the largest specimens of B. callista (18.5 and 18.2 mm postorbital carapace length, respectively, versus a maximum of 12–16 mm cl. for the other species of the genus).

Babamunida kanaloa , however, is distinct from all its congeners in:

—having the pereopods 2–4 propodi furnished on the entire extensor margin with spines including short rows of minute spines between the large dorsal spines ( B. brucei and B. hystrix have some proximal spines only),

—having the largest palm compared to postorbital carapace length (1.0, the remaining species have a ratio between 0.6 [ B. brucei and B. plexaura ] and 0.8 [ B. callista and B. javieri ]).

This character will have to be revisited if a female or smaller specimen is collected.

The live coloration also appears to be distinct for B. kanaloa , most similar to B. hystrix but B. kanaloa distinctly shows two red bands on the cheliped fingers instead of one wide median band as in B. hystrix (figure 1).

Distribution and Ecology. Hawaiian Archipelago and Johnston Atoll. The holotype from French Frigate Shoals, Northwestern Hawaiian Islands, 236–255 m is the only specimen collected to date. Additionally, observations, and frequently images, of this species have been recorded on several manned submersible dives conducted by the Hawaii Undersea Research Laboratory throughout the Hawaiian chain and at Johnston Atoll. This species has been observed to reside singly in small pockets and crevices on limestone substrates at depths of 145– 272 m. They have been seen to leave their shelters to grab bait deployed by the submersible and to avoid collection by the submersible’s suction device. In both cases they have moved rapidly to nearby holes, not always the original, rather than remain out in the open. Figure 3 shows individuals sitting in small pockets of a near vertical, limestone slope off Penguin Banks (southwest of the island of Molokai), with the anterior of the galatheid always facing out and with the abdomen tucked into the pockets and holes of the rock substrate.

Etymology. Kanaloa in ancient Hawaiian refers to the god of the oceans. Used as a noun in apposition.

Molecular analysis. For both the partial 16S rRNA and CO1 mtDNA sequences, the results unequivocally support the taxonomic position of the new species, confirming it as a species of Babamunida .

After alignment of the 16S sequences, the resulting dataset contained 536 characters, of which 378 were constant and 79 were parsimony informative. Divergences between B. kanaloa and its congeners ranged from 5.5–11.8% with B. hystrix being the closest and B. plexaura the most distant relative for this gene ( Tab. 1 , Fig. 4A ). The close relationship between B. kanaloa and B. hystrix corroborates the strong morphological similarities between these two species. This range of intrageneric divergences is similar to divergences reported by Cabezas et al. (2008). Intergeneric divergences are also in the range previously reported with Munida subrugosa more closely related than Crosnierita dicata , Agononida procera and Munida acantha ( Tab. 1 , Fig. 4A ).

The aligned CO1 sequences contained 657 characters of which 434 were constant and 127 were parsimony informative. The closest relative to Babamunida kanaloa , again, was its congener B. hystrix with 9.6% sequence difference ( Tab. 2 , Fig. 4 B). The remaining species of the genera Agononida , Alainius , Leiogalathea and Munida exceed 18.4% sequence divergence. Again, intrageneric divergences lie within the range reported by Cabezas et al. (2008) and intergeneric divergences reported for a range of other decapod Crustacea ( Costa et al. 2007).

Figures

FIGURE 1. Babamunida kanaloa n. sp. holotype, 3, LACM CR 2006 - 014.21. Colour image taken after collecting and freezing on board ship.

FIGURE 2. Babamunida kanaloa n. sp. holotype, 3, LACM CR 2006 - 014.21. A, carapace and abdomen, dorsal. B, rostral spines, ocular and antennal peduncles, lateral. C, sternal plastron. D, antennules, left antenna and epistomal ridges, ventral. E, endopod of third maxilliped, right, lateral. F, same, mesial ridge, right. G, telson. H, right pereopod 1, dorsal. I – K, right pereopods 2 – 4, lateral. L, dactylus and distal portion of propodus of right pereopod 3, lateral. M, detail of extensor margin of pereopod 2 propodus. Scales: 2 mm.

FIGURE 3. Babamunida kanaloa n. sp. as observed (video frame) during a dive of the DSV Pisces IV off Penguin Banks (southwest of Molokai), 20 ° 58.536´N, 157 ° 22.731´W, 224 m, November 2006. Arrows denote live specimens. Note distinctive colour banding on the chelipeds.

FIGURE 4. A, Maximum parsimony tree based on 16 S rRNA gene sequences. B, Maximum parsimony tree based on CO 1 mtDNA gene sequences. Numbers indicate bootstrap values (1000 replicates).

Tables

TABLE 1. Percentage divergences for 16 S rRNA between Babamunida kanaloa n. sp. and its congeners and closely related genera within Galatheidae.

Babamunida kanaloa
B. hystrix	5.53
B. javieri	8.29	10.30
B. plexaura	11.81	12.31	12.31
Crosnierita dicata	13.82	16.33	14.82	12.81
Agononida procera	13.82	14.32	13.57	12.31	11.31
Munida acantha	16.33	16.33	13.82	13.32	13.32	13.32
M. subrugosa	13.07	14.07	12.56	12.06	14.32	12.31	8.29

TABLE 2. Percentage divergences for CO 1 mtDNA between Babamunida kanaloa n. sp. and its congeners and closely related genera within Galatheidae.

Babamunida kanaloa n.sp.
Babamunida hystrix	9.60
Alainius crosnieri	18.45	16.62
Agononida sphaecia	18.75	17.84	16.92
Munida zebra	18.45	18.14	17.38	16.16
Leiogalathea laevirostris	20.88	21.34	19.97	18.75	19.36