Glyphocrangon serratirostris, Komai & Yang & Chan, 2020

Komai, Tomoyuki, Yang, Chien-Hui & Chan, Tin-Yam, 2020, Deep-sea shrimps of the genus Glyphocrangon A. Milne-Edwards, 1881 (Decapoda: Caridea: Glyphocrangonidae) collected by the SJADES 2018 expedition off Java, Indonesia, with description of one new species, Raffles Bulletin of Zoology 68, pp. 636-653 : 645-652

publication ID	https://doi.org/ 10.26107/RBZ-2020-0079
publication LSID	lsid:zoobank.org:pub:4A6F3831-7B0E-4A3F-B7A7-A0663846372F
persistent identifier	https://treatment.plazi.org/id/20636598-0447-4EC0-9A91-1C12ACF2067B
taxon LSID	lsid:zoobank.org:act:20636598-0447-4EC0-9A91-1C12ACF2067B
treatment provided by	Diego
scientific name	Glyphocrangon serratirostris
status	sp. nov.

Treatment

Glyphocrangon serratirostris , new species

( Figs. 1D View Fig , 6–10 View Fig View Fig View Fig View Fig View Fig )

Material examined. Holotype: SJADES 2018, stn CP 23, Sunda Strait (S of Panaitan Island), 06°46.74′S, 105°09.24′E to 06°45.92′S, 105°08.36′E, 559–571 m, gravel with mud, 27 March 2018, beam trawl, ovigerous female (cl 22.0 mm), MZB Cru5055. GoogleMaps

Paratypes: SJADES 2018, stn CP 12, Sunda Strait (SE of Tabuan Island), 05°52.25′S, 104°56.79′E to 05°52.73′S, 104°56.42′E, 615–698 m, mud, 25 March 2018, beam trawl, 1 ovigerous female (cl 20.0 mm), ZRC 2020.0298 View Materials GoogleMaps ; same data as preceding, 2 females (cl 16.0, 16.2 mm), 2 ovigerous females (cl 19.1, 21.2 mm), 3 males (cl 17.2, 17.7, 20.0 mm), ZRC 2020.0306 View Materials GoogleMaps ; same data as holotype 1 female (cl 13.6 mm), ZRC 2020.0307 View Materials GoogleMaps ; stn CP 26, E of Tinjil Island , 06°57.22′S, 105°54.75′E to 06°56.66′S, 105°55.32′E, 517–727 m, 28 March 2018, beam trawl, 1 ovigerous female (cl 21.0 mm), ZRC 2020.0308 View Materials GoogleMaps ; stn CP 48, S of Tg. Gedeh , Java, 07°51.12′S, 107°46.25′E to 07°51.72′S, 107°46.38′E, 689– 637 m, mud, 1 April 2018, beam trawl, 1 male (cl 20.0 mm), ZRC 2020.0299 View Materials GoogleMaps .

Description. Females. Body ( Figs. 6 View Fig , 7A, E View Fig ) moderately robust. Integument glabrous, without dense pubescence or scattered short setae.

Rostrum ( Figs. 6 View Fig , 7A–D View Fig , 10A View Fig ) slightly descending, upturned in distal one-third, 0.6–0.8 times as long as carapace, each lateral margin armed with 4–7 spines and occasionally few minute tubercles in proximal half (2–5 additional spines and tubercles between 2 principal spines, these additional spines smaller than principal spines), posterior pair with sinuous dorsal margin; dorsal surface anterior to anterior pair of lateral spines faveolate, with 1 pair of tubercles between posteriormost lateral spines; posterior half of middorsal carina distinct, bearing row of 10–15 small tubercles becoming larger posteriorly; dorsolateral ridges between 2 main lateral spines moderately raised; ventral surface faintly sulcate even in distal part, ventrolateral margins sharply carinate.

Carapace ( Figs. 6 View Fig , 7A View Fig ) 1.1 times as long as wide (distance between tips of anterior spines of posterior third carinae); surfaces of carinae and tubercles etched with minute pits; major carinae well demarcated. Anterior first (submedian) carina composed of 6 tubercles, these tubercles forwardly directed, somewhat compressed laterally, anteriormost 1 or 2 tubercles acuminate and others blunt ( Fig. 8A View Fig ); posterior first carina composed of 4 or 5 tubercles, directed forward, or upward, anterior 3 or 4 tubercles bluntly pointed, posteriormost tubercle blunt or subacute ( Fig. 8A View Fig ). Anterior second (intermediate) carina composed of 4 or 5 tubercles, anteriormost one acutely pointed, others blunt; posterior second carina weakly arched in lateral view, composed of 5 or 6 lobes or tubercles, all directed anteriorly, blunt. Anterior third (antennal) carina confined to antennal spine; posterior third carina terminating anteriorly in small, anterolaterally directed spine, divided into 3 or 4 lobes followed by 1 or 2 tubercles ( Fig. 8B, D View Fig ). Anterior fourth (lateral) carina expanded into single large, vertically compressed, acute lamina directed anterolaterally, slightly overreaching posterior margin of orbit, followed by 1 or 2 blunt tubercles; distance between tips of laminae slightly greater than carapace length; posterior fourth carina upturned posteriorly, angular at anterior end, divided into 4 or 5 lobes and 1 tubercle. Anterior fifth (sublateral) carina clearly delimited, surface strongly eroded ( Fig. 8D View Fig ); posterior fifth carina short but clearly delimited, surface roughly eroded ( Fig. 8D View Fig ). Sixth (submarginal) carina showing as broad elevation with roughly pitted surface, extending posteriorly along marginal carina to submarginal posterolateral ridge of carapace, flanked by longitudinal row of blunt tubercles ( Fig. 8D View Fig ). Submarginal posterolateral ridge separated from marginal posterolateral corner by deep groove ( Fig. 8D View Fig ). Orbital margin elevated, traversed by shallow groove; postorbital region with 4 or 5 conical, spiniform tubercles and 1 conspicuous tubercle below base of rostral lateral spine. Median part of gastric region with 2 anteromedian tubercles and 2 longitudinal rows of tubercles (each row with 8–12 tubercles), most of these tubercles as high as first carina, somewhat compressed laterally, none with acute apex; posteromedian part also with 2 longitudinal rows of blunt tubercles lower than first carina (each row with 5 tubercles). Lateral part of gastric region with space between first and second carinae having 2 longitudinal rows of tubercles (these tubercles similar to those on median part); space between second carina and lateral groove with single longitudinal row of tubercles. Posterior dorsolateral region with 3 longitudinal rows of blunt tubercles. Upper part of hepatic region bearing 25–30 scattered tubercles, anterior few tubercles spiniform ( Fig. 8C View Fig ); lower part of hepatic region with single longitudinal row of blunt tubercles ( Fig. 8D View Fig ). Branchial region with upper part bearing about 35–40 blunt, compressed tubercles arranged in 3 longitudinal rows, these tubercles anteriorly directed; middle part with 25–30 tubercles arranged in 3 longitudinal rows, similar in shape to those on upper part; lower part with blunt, compressed tubercles arranged in irregular 2 rows. Space between anterior fifth and sixth carinae with blunt tubercles in single longitudinal row. Antennal spine strong, mesially curved, ascending (angle against horizontal plane about 20°), reaching nearly to distal corneal margin. Branchiostegal spine strong, directed anteriorly in dorsal and lateral views, reaching beyond level of distal corneal margin, hardly visible in dorsal view; lateral face without ridges or carinae. Marginal posterolateral corner flared laterally, distinctly angulate. Anterior and cervical grooves deep.

Pleon ( Figs. 6 View Fig , 7E View Fig ) thickly covered with numerous prominent tubercles, none with acute tip. Pleomere 1 with median elevation defined by deep transverse groove, with 3 small tubercles in obliquely transverse row on either side of median carina; median carina showing as large, strongly compressed tooth with forwardly directed, acute apex; posterior part of tergum with several laterally compressed tubercles on either side of midline. Dorsolateral carina showing as strong tooth with forwardly directed, acute apex and slightly sinuous dorsal margin. Lateral carina composed of two tubercles. Pleuron ornamented anteriorly with several tubercles; posterior depression abruptly delimited; anteroventral corner slightly produced, bluntly pointed.

Pleomeres 2 to 4 with median carinae strongly compressed laterally, crested; tubercles or prominences composing submedian or dorsolateral carinae compressed laterally; surfaces of carinae and tubercles weakly etched. Posterior transverse grooves moderately narrow, deep. Vertical ridges on pleura 3 and 4 each with blunt spiniform tubercle at ventral end. Pleural spines strong, acute, unequal in length (anterior spine longer than posterior spine in each pleuron), each anterior spine gently curved posteriorly, posterior spines nearly straight. Pleomere 2 with anterior part of median carina slightly produced anterodorsally into blunt tooth, posterior part rounded. Pleomere 3 with anterior part of median carina slightly produced anteriorly, posterior part longer than anterior part, somewhat produced posteriorly into blunt projection. Pleomere 4 with anterior part of median carina much shorter than posterior part, its posterior end not produced; posterior part of median carina bearing median groove, produced posteriorly in bluntly triangular projection.

Pleomere 5 anterior part of median carina posteriorly directed, bluntly triangular in lateral view; posterior part of median carina produced into bluntly triangular projection. Tergum with shallow oblique groove; anterior submedian carinae showing as short crest; posterior submedian carinae slightly diverging, not reaching to posterodorsal margin, each with median groove; 2 strong pleural spines, directed posteriorly, slightly unequal with posterior spine longer.

Pleomere 6 with highly crested median carina, principally divided into 2 parts by narrow V-shaped notch ( Fig. 8F View Fig ), anterior part terminating posteriorly in subacute tip, posterior part produced posteriorly into strong, subacute tooth, dorsal margin slightly sinuous in lateral view. Tergum with some tubercles arranged in 3 longitudinal rows on either side of middorsal carina. Lateral carina composed of laterally compressed, posteriorly directed tubercles. Pleuron with several small tubercles; lateroventral carina composed of row of tubercles; posteroventral spine prominent, without support of carina.

Telson ( Fig. 7E, F View Fig ) about 0.7 times as long as carapace; anterior projection on dorsal surface prominent, laterally compressed, bi-spined. Dorsolateral carinae each with row of small, posteriorly directed tubercles in anterior 0.6; ventrolateral carinae similarly distinctly tuberculate in anterior half.

Cornea ( Figs. 6 View Fig , 7A View Fig ) darkly pigmented in preservative, corneal width about 0.2 of carapace length. Ocular peduncle with small, papilla-like process on anteromesial face (not illustrated).

Antennular peduncle ( Fig. 7A View Fig ) overreaching anterior margin of antennal scale by half length of article 3; article 2 slightly widened anteriorly, about twice as long as wide. Antennal scale ( Figs. 7A View Fig , 8G View Fig ) oval, 0.4 times as long as carapace, 1.6 times as long as wide, without trace of lateral tooth; setal row extending nearly to proximal end of lateral margin; carpocerite (article 5 of antennal peduncle) falling short of anterior margin of antennal scale.

Maxilliped 3 ( Fig. 9A, B View Fig ) moderately stout for genus, reaching level of anterior margin of antennal scale. Ultimate article subequal in length to penultimate article, tapering to acute, basally demarcated unguis, armed with several strong spiniform setae on margins and mesial face. Penultimate article (= carpus) with 3 (lateral), 2 (mesial), and 1 (distomesial) spiniform setae. Antepenultimate article (merusischium-basis fused article) with dorsolateral margin sharply carinate; distomesial face somewhat inflated; ventral surface rounded, with 2 subterminal small spiniform setae. Exopodal flagellum not reaching distal end of antepenultimate article.

Pereopod 1 ( Fig. 9C View Fig ) not reaching midlength of antennal scale; palm glabrous on lateral face; carpus short, cup-like; merus lateral surface with 1 obsolete longitudinal ridge adjacent to dorsal margin, ventral margin bluntly ridged; ventral lamina of ischium prominent, bluntly pointed distally. Pereopods 2 slightly unequal and dissimilar, right more slender than left; left ( Fig. 9D View Fig ) overreaching antennal scale by length of chela and 0.3 of carpus, carpus subequal in length to merus and ischium combined, divided into 23–29 articles; right ( Fig. 9E View Fig ) carpus divided into 28–33 articles.

Pereopod 3 ( Fig. 9F View Fig ) moderately slender, overreaching level of anterior margin of antennal scale by length of dactylus and 0.1 of propodus; dactylus compressed laterally, less than 0.2 times as long as propodus.

Pereopod 4 ( Fig. 9G View Fig ) moderately slender, reaching anterior margin of antennal scale by tip of dactylus; dactylus ( Fig. 9H View Fig ) 0.6 times as long as propodus, subspatulate, slender, terminating in acute apex, extensor surface shallowly grooved with sharply edged, elevated margins; propodus with tuft of stiff setae on dorsodistal margin, partially obscuring basal part of dactylus. Pereopod 5 ( Fig. 8I View Fig ) similar to pereopod 4; dactylus ( Fig. 9J View Fig ) 0.5 times as long as propodus.

Pleopods and uropod without distinctive features.

Eggs large, 2.3–2.5 × 2.7–2.8 mm.

Male characteristics. Generally similar to females. Carapace posterior third carina devoid of anterior spine ( Fig. 10B View Fig ). Pleon pleural spines relatively shorter ( Fig. 10C View Fig ). Outer antennular flagellum thicker compared with that of females. Pleopod 1 endopod ( Fig. 10D View Fig ) subovate with sinuous mesial margin; appendix interna subterminal, distinctly overreaching distal margin of endopod. Pleopod 2 ( Fig. 10E View Fig ) appendix masculina longer than appendix interna, bearing numerous long bristle-like setae.

Colouration in fresh condition. Rostrum generally red, partially whitish; carapace dorsum reddish with tubercles vivid red; antennal and branchiostegal spines also red; lateral part whitish; pleon reddish dorsally with tubercles vivid red and whitish laterally, pleural spines reddish; cornea darkly pigmented, reflective; antennule, antenna, and thoracic appendages red; protopods of pleopods reddish, rami whitish; uropod red; eggs olive green ( Figs. 1D View Fig , 6 View Fig ).

Distribution. Presently known only from the south of West Java; 517– 727 m.

Etymology. The specific epithet is derived from the combination of serratus (L., saw-shaped) and rostrum (L., beak), in reference to the characteristic armature of the lateral margin of the rostrum in the new species. Used as a noun in apposition.

Remarks. Glyphocrangon serratirostris , new species, is referred to the Glyphocrangon regalis species complex as diagnosed by Komai (2004b). This group includes the following 17 species other than G. regalis : G. aculeata (Atlantic) , G. amblytes (western Indian Ocean), G. andamanensis Wood-Mason & Alcock, 1891 (Andaman Sea), G. armata Komai, 2004b ( New Caledonia), G. boa Komai, 2011 ( Vanuatu) , G. boletifera Komai, 2004b (Gulf of Aden), G. conodactylus Komai, 2004b ( New Caledonia), G. investigatoris (Bay of Bengal), G. juxtaculeata ( Indonesia) , G. lineata Komai, 2004b ( Indonesia and Western Australia), G. longipes Komai, 2004b ( Philippines) , G. lowryi Kensley, Tranter & Griffin, 1987 ( Papua New Guinea to eastern Australia), G. perplexa Komai, 2004b ( Japan and Taiwan), G. pulchra Komai & Chan, 2013 ( Mozambique Strait), G. smithii Wood-Mason & Alcock, 1891 (Bay of Bengal and Andaman Sea), G. tasmanica Komai, 2004b (Tasman Sea), and G. wagini Burukovsky, 1990 (Sala-y-Gomez Ridge, eastern Pacific). In the well-developed tubercles covering the carapace and pleon surfaces, and the presence of a small spine at the anterior end of the posterior third carina of the carapace, the new species appears most similar to G. longipes , G. lowryi , and G. perplexa . Nevertheless, it is unique in the genus in having four to seven spines on each lateral margin of the rostrum. In all previously known species of the G. regalis species complex, the rostrum bears two pairs of lateral spines without exception. The markedly tuberculate middorsal carina of the rostrum and the presence of spiniform tubercles on the postorbital region of the carapace immediately distinguish G. serratirostris , new species, from the latter three species. In the latter three species, the middorsal carina of the rostrum bears posteriorly only a few blunt tubercles; the postorbital region of the carapace is devoid of tubercles or has only a few minute granules. The strongly tuberculate margins of the telson also distinguish the new species from G. longipes and G. perplexa , in which the latter two only have the proximal parts being faintly tuberculate.

Glyphocrangon serratirostris , new species, also resembles G. andamanensis and G. investigatoris in the strongly developed tubercles on the carapace and pleon, but the latter two are readily distinguished from the new species in the lack of an anterior spine on the posterior third carina, in addition to the rostral armature.

Genetic analysis shows strong support for a clade containing the G. regalis species complex ( Fig. 11 View Fig ), and COI sequence divergence values of 4% or more between G. serratirostris and its comparable congeners (Table 2).