Phylladiorhynchus bahamut, Rodríguez-Flores & Macpherson & Machordom, 2021

Rodríguez-Flores, Paula C., Macpherson, Enrique & Machordom, Annie, 2021, Revision of the squat lobsters of the genus Phylladiorhynchus Baba, 1969 (Crustacea, Decapoda, Galatheidae) with the description of 41 new species, Zootaxa 5008 (1), pp. 1-159 : 23-24

Phylladiorhynchus bahamut n. sp.

( Figs. 6 , 11G )

Phylladiorhynchus integrirostris .— Lewinsohn, 1982: 295, fig. 1 (Gulf of Aqaba, N Red Sea).

Type material. Holotype. Saudi Arabia, Yanbu , Ras Majiz, highly dissected reef, 38.2761°N, 23.7725°E, 4–8 m, 3 March 2014: M 2.5 mm ( UF40205 ).

Etymology. From Bahamut, a Persian sea monster supporting the structure that holds up the earth. The name is a substantive in apposition.

Description. Carapace: As long as or slightly longer than broad; transverse ridges with dense short setae and some scattered iridescent thick long setae. Gastric region slightly convex with 4 transverse ridges: epigastric ridge distinct with 2 median spines, short scales laterally; anterior protogastric ridge not medially interrupted, nearly extending laterally to carapace margin; anterior mesogastric ridge not medially interrupted, laterally continuing to first branchial spine; anterior metagastric ridge not medially interrupted, followed by median scale. Mid-transverse ridge not interrupted, medially depressed, cervical groove indistinct, followed by 2 not interrupted or minutely interrupted ridges, interspersed with 1 short lateral ridge and few short scales. Lateral margins convex, with 5 distinct spines: first anterolateral spine well-developed, reaching anteriorly to level of lateral orbital spine, second spine (hepatic) small, slightly dorsomesially from lateral margin, and followed by 3 branchial spines (2 anterior and 1 posterior). Rostrum leaf-like, horizontal, dorsally slightly concave, [1.4] × as long as broad, length [0.4] and breadth [0.2] that of carapace; lateral margins minutely serrated and convex, with well-developed supraocular basal spines, subapical spines absent. Pterygostomian flap ending in sharp tooth, upper margin smooth.

Thoracic sternum: As wide as long. Sternite 3 moderately broad, [1.7] × as wide as long, anterior margin serrated and convex, with a median projection. Sternite 4 widely contiguous to sternite 3; anterolaterally serrated, surface flattish, smooth; greatest width [3.2] × that of sternite 3, [2.9] × as wide as long.

Pleon: Elevated ridges with short setae and a few scattered long setae. Tergite 2 with anterior and posterior transverse elevated ridges; tergites 3–4 with anterior transverse ridge only; tergites 5–6 smooth.

Eye: Eyestalk length about [1.1] × broader than long, peduncle distally setose, not distinctly expanded proximally; cornea expanded distally, posterior margin irregular, maximum corneal diameter [1.1] × rostrum width, as wide as or wider than eyestalk.

Antennule: Article 1 slightly longer than wide, with 5 distal spines: distomesial spine well-developed; proximal lateral spine small, obsolescent.

Antenna: Article 1 with prominent mesial process, nearly reaching end of lateralmost antennular spine. Article 2 with well-developed distomesial and distolateral spines. Articles 3 and 4 unarmed.

Mxp3: Ischium with distinct distal spines on flexor and extensor margins. Merus [0.8] × length of ischium, with well-developed distal spine on extensor and flexor margins.

P1: [3.3] (male) × carapace length; subcylindrical, spiny and with long stiff setae, without plumose setae; merus, carpus and palm with spines along mesial, dorsal and lateral surfaces, distal and mesial spines usually stronger than others. Merus [1.1] length of carapace, [1.6] × as long as carpus. Carpus [1.8] × as long as wide. Palm [1.3] × carpus length, [2.1] × as long as broad. Fingers [0.7] × palm length; fixed finger unarmed; movable finger with small basal spine.

P2–4: Slender, densely setose and spinose. Meri successively shorter posteriorly: P3 merus [0.9] × length of P2 merus; P4 merus [0.9] × length of P3 merus. P2 merus [4.7] × as long as broad, [1.3] × as long as P3 propodus; P3 merus [3.4] × as long as broad, [1.2] × as long as P3 propodus; P4 merus [3.6] × as long as broad, [1.1] × as long as P4 propodus; extensor margin of P3 with row of spines, proximally diminishing, with prominent distal spine; P4 extensor margin irregular, unarmed; flexor margin irregular, with distal spine on P3, distal spine absent in P4. Carpi with 1–3 spines on extensor margin on P3, unarmed on P4; distal spine prominent on P3, smaller on P4; granules below extensor margin on lateral surface of P3–4; flexor margin unarmed. Propodi stout, [4.5–4.6] × as long as broad; extensor margin irregular, armed with 2–4 spines; flexor margin with 3–4 slender movable spines in addition to distal pair. Dactyli [0.6] × length of propodi, ending in incurved, strong, sharp spine; flexor margin with 4 movable spines.

Eggs: No data.

Live colour. Unknown.

Genetic data. COI and 16S, Table 1.

Distribution. Red Sea, from 4 to 8 m.

Remarks. Phylladiorhynchus bahamut agrees with the species recorded and illustrated by Lewinsohn (1982) from the Gulf of Aqaba, who also pointed out that it might be a different species than P. integrirostris . Phylladiorhynchus bahamut belongs to the group of species having 2 median epigastric spines, the hepatic margin with a small spine and 2 spines on the anterior branchial margin. The closest species is P. peneleos (see the differences under the Remarks of this species).

Figures

FIGURE 6. Phylladiorhynchus bahamut n. sp., holotype male 2.5 mm (UF40205): A, carapace and pleon, dorsal view. B, thoracic sternites 3 and 4. C, right cephalic region, showing antennular and antennal peduncles, ventral view. D, left Mxp3, lateral view. E, right P1, dorsal view. F, left P2, lateral view. G, left P3, lateral view. H, left P4, lateral view. I, dactylus of left P2, lateral view. Scale bars: 1.0 mm.

FIGURE 11. Rostrum, dorsal view. A, Phylladiorhynchus acastus n. sp., paratype male 2.6 mm (MNHN-IU-2017-2646). B, P. amphion n. sp., holotype male 2.4 mm (WAM C55691). C, P. amphion n. sp., paratype female 2.6 mm (WAM C53887). D, P. argus n. sp., paratype ovigerous female 3.5 mm (MNHN-IU-2014-23836). E, P. asclepius n. sp., paratype ovigerous female 2.1 mm (UF22401). F, P. australis Schnabel & Ahyong, 2019, female 4.0 mm (MNHN-IU-2019-2596). G, P. bahamut n. sp., holotype male 2.5 mm (UF40205). H, P. barbeae n. sp., paratype male 2.2 mm (MNHN-IU-2019-2643). I, P. boucheti n. sp., paratype ovigerous female 2.5 mm (MNHN-IU-2017-3830). J, P. butes n. sp., paratype female 2.1 mm (MNHN-IU-2016-449). K, P. cepheus n. sp., paratype male 2.4 mm (MNHN-IU-2014-13858). L, P. eneus n. sp., paratype male 2.1 mm (MNHN-IU- 2014-13801). Scale bars = 1 mm.