Typton fapespae, Almeida, Alexandre O., Anker, Arthur & Mantelatto, Fernando L., 2014

Almeida, Alexandre O., Anker, Arthur & Mantelatto, Fernando L., 2014, A new snapping species of the shrimp genus Typton Costa, 1844 (Decapoda: Palaemonidae) from the coast of São Paulo, southeastern Brazil, Zootaxa 3835 (1), pp. 110-120 : 111-119

Typton fapespae sp. nov.

( Figs. 1–5 )

Typton gnathophylloides — Nalesso et al. 1995: 96; Duarte & Nalesso 1996: 143; Amaral et al. 2010: 249 [not T. gnathophylloides Holthuis, 1951 ]

Type material. Brazil, coast of São Paulo. Holotype: male (pocl/cl 3.0/ 3.7 mm), São Sebastião, off Praia do Cabelo Gordo, 23°49’38.91”S 45°25’17.73”W, free diving, depth: less than 5 m, in sponge growing on large rock, coll. M. Tavares, J.B. Mendonça, A. Anker and P.P.G. Pachelle, 30 Oct. 2013 [ MZUSP 31127]. Paratypes: 2 males (pocl/cl 2.6/ 3.3 mm, 2.8/ 3.4 mm), 2 ovigerous females (pocl/cl 2.3/ 2.7 mm, 3.4/4.0 mm), same collection data as for the holotype [ MZUSP 31128–31131]; 1 male (pocl/cl 2.4/ 2.9 mm), Ubatuba, Praia do Cedro, 23º27’33.76”S 45º02’3.50”W, scuba diving, depth: 7–8 m, in Mycale (Zygomycale) angulosa , coll. F. Zara, 31 Aug. 2012 [ CCDB 4486]; 1 female (pocl/cl 1.9/ 2.3 mm), Ubatuba, Praia de Itaguá, 23º27’05”S 45º02’48”W, scuba diving, depth: less than 3 m, in Schizoporella errata ( Waters, 1878) (Gymnolaemata: Schizoporellidae ), coll. I. Leone et al., 5 Apr. 2011 [ CCDB 3413].

Additional material. 2 males (pocl/cl 4.2/ 4.9 mm), 2 females (pocl/cl 4.0/ 4.5 mm), Ubatuba, Praia Lamberto, 23°29’56.91”S 45°7’2.50”W, 5 Sep. 1975 [ ZUEC CRU 14]; 2 males (pocl/cl 4.1/ 4.6 mm, 3.6/ 4.1 mm), 3 specimens in poor condition, São Sebastião, Praia do Araçá, 23°48’78.1”S 45°24’46.9”W, 26 Jan. 1975 [ ZUEC CRU 20]; 9 males (pocl/cl 1.5–2.9 mm / 2–3.4 mm), 7 females (pocl/cl 2.8–4.2/3.6–4.7) São Sebastião, Praia do Araçá, 23°48’78.1”S 45°24’46.9”W, 14 Sep. 1974 [ ZUEC CRU 21]; 11 males (pocl/cl 2.8–4.8 mm / 3.4–5.1 mm), 4 females (pocl/cl 4.1–4.9 mm / 4.6–5.4 mm), São Sebastião, Praia do Araçá, 23°48’78.1”S 45°24’46.9”W, 6 Jul. 1974 [ ZUEC CRU 22]; 1 male (pocl/cl 4.2/ 4.6 mm), 1 female (pocl/cl 3.8/ 4.4 mm), Ubatuba, Praia Lamberto, 23°29’56.91”S 45°7’2.50”W, 10 Jun. 1974 [ ZUEC CRU 31].

Description. Carapace smooth, glabrous, slightly depressed, longer than deep. Rostrum arrow-shaped in dorsal view ( Fig. 1 A), usually reaching base of cornea and sometimes extending beyond distal margin of eyes and half-length of dorsally visible part of first article of antennular peduncle, straight to slightly curving upwards, tip with single small seta ( Fig. 1 A–C). Paraorbital processes ( Fig. 1 A–C) well developed, usually exceeding halflength of rostrum and half-length of cornea in lateral view, reaching level of most-anterior pterygostomial margin, non-divergent in dorsal view, pointing straight-forward or slightly upward in lateral view ( Fig. 1 A–C). Orbit ( Fig. 1 B, C) feebly demarcated, without distinct infero-orbital angle or antennal spine; pterygostomial margin ( Fig. 1 B, C) slightly produced anteriorly, rounded to somewhat angular. Posteroventral margin of carapace rounded, with slight cardiac concavity ( Fig. 1 D).

Abdomen ( Fig. 1 E) elongate, smooth, glabrous; first five somites ( Fig. 1 E) with rounded pleura; posterodorsal margin of sixth somite ( Fig. 1 F) with strong, sharp, subtriangular, median tooth; posterolateral angle of sixth somite ( Fig. 1 E–G) produced into strong acute tooth, posteroventral angle blunt, not posteriorly produced; first to third and sixth sternites unarmed, fourth and fifth each with low, rounded, median process.

Telson ( Fig. 1 H) moderately slender, about 2.2 times as long as anterior width, posterior margin width about 0.35 times width of anterior margin; lateral margins slightly convex, tapering distally; dorsal surface with two pairs of well-developed spines, each about 0.1 of telson length, inserted at about 0.25 (anterior pair) and 0.6 (posterior pair) telson length; posterior margin ( Fig. 1 I, J) broadly rounded with minute median point; three pairs of spines present as following: small lateral spines and longer intermediate and submedian spines, intermediate being 2.0–2.8 times as long as lateral and 1.3–1.6 times as long as submedian ( Fig. 1 I).

Antennular peduncle ( Figs. 1 A, 2A) slender, with proximal article subcylindrical, 3.8 times as long as distal width; statocyst well-developed, with statolith; stylocerite short, narrow; intermediate article shorter than distal article, their combined length equal to about 0.4 of proximal article length; lateral (= upper) flagellum ( Figs. 1 A, 2A) short, first two articles of rami fused, stout, with 7–8 groups of aesthetascs, short ramus distally obsolete, longer ramus with 5–6 segments; mesial (= lower) flagellum long, with 9–10 segments. Antenna with antennal gland tubercle mesially; basicerite stout, unarmed laterally; scaphocerite ( Fig. 2 C, D) vestigial, about 1.8 times as long as greatest width, terminally obliquely rounded, margins non-setose; carpocerite ( Fig. 2 B) slender, not reaching end of antennular peduncle; flagellum ( Fig. 2 A) short, about 2.6 times as long as carpocerite.

Mouthparts not dissected. Third maxilliped ( Fig. 2 E) with broad antepenultimate article, with both dorsal and ventral margins strongly convex; penultimate article about half as long as antepenultimate article, much more slender, with straight margins, ultimate article most slender, tapering towards apex; exopod well developed.

First pereiopod ( Fig. 2 F) slender; ischium about three times as long as wide, unarmed; merus about five times as long as broad, slightly longer than carpus; carpus subcylindrical, broadening distally, about four times as long as broad and 1.5 times as long as chela; carpo-propodal brush lacking; chela with palm subcylindrical, slightly compressed; fingers robust, subspatulate, about 0.4 of chela length, with feebly bidentate tips.

Major second pereiopod ( Figs. 2 G–J, 4, 5) greatly enlarged, much longer and more robust than minor second pereiopod; largest adult males with massive chela equaling combined length of cephalothorax and abdomen ( Figs. 4 , 5 A), females with much smaller chela, equaling or slightly exceeding length of cephalothorax ( Fig. 5 B); ischium subequal to merus in length, unarmed; merus ( Fig. 2 I) about 1.3 times as long as broad, about 0.6 length of carpus and 0.2 length of palm, ventral surface with small, conical, distally more or less sharp teeth; carpus ( Fig. 2 G, H) 0.3–0.4 length of palm, smooth, 1.6 times as long as maximal width, narrow proximally, distally widening, distoventral surface somewhat excavated; chela ( Fig. 2 G, H, J) very large, with palm smooth, slightly compressed laterally, suboval in cross-section, flattened medially, slightly tapering distally, about twice as long as maximal height; dactylus ( Fig. 2 J) laterally compressed, about twice as long as maximal height, about 0.4 times length of palm; tip strongly curved, corneous; cutting edge conspicuously thickened, forming large bulge; pollex about as long as dactylus; tip curved, corneous; surface opposed to dactylus with relatively large and deep groove accommodating dactylar bulge, mesial and lateral margins entire, concave.

Minor second pereiopod variously but always significantly smaller than major second pereiopod ( Figs. 2 K–N, 4, 5); ischium ( Fig. 2 K) about 1.4 times length of merus, unarmed; merus ( Fig. 2 K) 1.5 times as long as broad, about 0.7 of carpal length and 0.4 of palm length, with minute conical teeth on ventral surface; carpus ( Fig. 2 K, L) about 0.7 length of palm, smooth, about twice as long as maximal height, much wider distally; palm ( Fig. 2 K, L) smooth, non-setose, suboval in cross-section, about 1.8 times as long as maximal height; dactylus ( Fig. 2 K–N) about 0.6 length of palm, compressed, with curved tip; cutting edge sharp, with blunt proximal tooth laterally; pollex excavated on surface opposed to dactylus; lateral edge sharp, nearly entire; mesial edge projecting proximally as strong subtriangular tooth; finger tips simple.

Third pereiopod ( Fig. 3 A, D) stout, with ischium about 0.8 times length of merus, unarmed; merus ( Fig. 3 A) about twice as long as broad and 1.2 times length of carpus, unarmed; carpus ( Fig. 3 A) about 0.9 length of propodus, nearly three times as long as distal width, unarmed; propodus ( Fig. 3 A, D) about 2.8 times as long as wide, ventral margin with four or five irregularly spaced spines, distal pair of stouter spines fringing base of dactylus; dactylus ( Fig. 3 A, D) biunguiculate, compressed, about 0.25 of propodus length and 2.2 times longer than basal width, ventral margin of corpus slightly concave, crenulated, with acute, triangular, ventrally pointing secondary unguis; terminal unguis distinctly demarcated, about half as long as corpus, strongly curved, not crenulated proximally. Fourth pereiopod ( Fig. 3 B, E) generally similar to third pereiopod; merus ( Fig. 3 B) about 2.4 times as long as wide; carpus ( Fig. 3 B) slightly longer than propodus, about three times as long as distal width; propodus ( Fig. 3 B, E) about three times as long as wide; ventral margin with three or four spines and distal pair of stouter spines; dactylus ( Fig. 3 B, E) biunguiculate, nearly twice as long as basal width; ventral margin of corpus conspicuously crenulated, with triangular, ventrally pointing secondary unguis; terminal unguis equal or slightly shorter than half-length of corpus.

Fifth pereiopod ( Fig. 2 C, F) noticeably more slender than third and fourth, with ischium about 0.6 length of merus, unarmed; merus ( Fig. 2 C) about 3.5 times as long as wide and 1.4 length of carpus, unarmed; carpus ( Fig. 2 C) 0.8 times length to propodus, about 3.3 times as long as distal width, unarmed; propodus ( Fig. 2 C, F) about 4.5 times as long as broad; ventral margin with one subdistal and one distal spines; distolateral surface with brush of grooming setae; dactylus ( Fig. 2 C, F) biunguiculate, compressed, about 0.2 of propodus length, 2.3 times as long as basal width; ventral margin of corpus slightly convex, distally conspicuously crenulated, with strong, subacute, ventrally pointing secondary unguis; terminal unguis well demarcated, more slender than that of third and fourth pereiopods, about half-length of corpus, curved, not crenulated proximally.

First male pleopod ( Fig. 3 G) with endopod not reaching half-length of exopod, about three times as long as proximal width, elongate, with rounded tip, lateral margin with four longer plumose setae, apex and mesial margin with several shorter setae. Second male pleopod ( Fig. 3 H) with endopod about 0.8 length of exopod, with appendix interna at about 0.4 length of mesial margin; appendix masculina with corpus obsolete, being essentially represented by two stiff setulose setae protruding beyond appendix interna.

Uropods ( Figs. 1 E, 3I –L) with protopod unarmed; exopod slightly longer than telson, with lateral margin slightly convex, non-setose; distolateral margin ( Fig. 3 I–L) serrated, with 2-6 acute or subacute teeth; distolateral angle with acute tooth, reaching approximately half-length of stout spine; diaeresis inconspicuous; endopod slightly longer than exopod; proximal parts of lateral and mesial margins non-setose.

Variation. The most obvious variable character is the length of the rostrum, which can extend beyond the distal margin of the cornea ( Fig. 1 A, B) or reach only to the middle of the cornea ( Fig. 1 C, 5). The paraorbital processes can be about as long as half-length of cornea ( Fig. 1 A, B) or significantly shorter ( Fig. 1 C, 5A). In addition, both the rostrum and the paraorbital processes are variable in their direction, pointing either straightforward or slightly upward (cf. Fig. 1 B and 1C). The pterygostomial region varies from broadly rounded ( Fig. 1 B) to more angularly protruding ( Fig. 1 C). The number of spines on the ventral margin of the P3 and P4 propodi varies from four to five and three to four, respectively. There is also a significant variation in the number of teeth on the distolateral margin of the uropodal exopod, ranging from 2–6 (not including terminal tooth adjacent to strong spine) ( Fig. 3 I–L).

Colour pattern. Uniform translucent yellowish to pale orange, with some scattered reddish and yellowish chromatophores ( Figs. 4 , 5 ); cornea silvery reddish; ovaries and freshly laid eggs yellow-orange ( Fig. 5 B).

Type locality. Brazil, São Paulo, São Sebastião (Praia do Cabelo Gordo).

Etymology. The new species is named after Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) for supporting studies on the origins, diversity and distribution of the flora and fauna of the State of São Paulo, especially through the Biota-FAPESP Program.

Distribution. Presently known only from São Sebastião and Ubatuba, northern coast of the state of São Paulo, southeastern Brazil.

Biology. Like most if not all species of the genus, T. fapespae sp. nov. appears to be an obligate associate of demosponges. All São Sebastião specimens collected by us were extracted from an unidentified sponge, whereas the male paratype from Ubatuba was found inside Mycale (Zygomycale) angulosa . The female paratype from Ubatuba was extracted from a colony of the bryozoan Schizoporella errata , most likely having escaped from a cryptic sponge growing inside or attached to the bryozoan colony. The specimens collected from the tangled matrix of tubes of the chaetopterid polychaete Phyllochaetopterus socialis and reported as T. gnathophylloides by Nalesso et al. (1995) were likely associated to cryptic sponges. Additional material reported by Duarte & Nalesso (1996) as T. gnathophylloides was also found inside Mycale (Zygomycale) angulosa , suggesting that this sponge may be the main host of T. fapespae sp. nov.

While photographing the São Sebastião specimens of T. fapespae sp. nov., the second author (AA) noticed that most shrimps in an irritated state produced a fairly strong snapping sound, presumably by rapidly closing the major second pereiopod, in a way similar to that of Periclimenaeus Borradaile, 1915 . Typton spongicola , a close eastern Atlantic relative of T. fapespae sp. nov. (see below), is also known to produce snapping sounds ( Johnston 1946). In both species, the pollex of the major chela of P2 is deeply depressed accommodating a large flat bulge of the dactylus ( Fig. 2 J; see also Bruce 2009: fig. 5A, B), a configuration that may be responsible for a mechanically induced snapping sound. Thorough studies determining the exact nature and physical properties of the snapping sound are needed for the snapping species of Typton , but also for Periclimenaeus and several other pontoniine genera.

Remarks. Only three other species of Typton have a strong median tooth on the posterodorsal margin of the sixth abdominal somite, viz. T. hephaestus (eastern Pacific), T. holthuisi (central Atlantic), and T. spongicola (eastern Atlantic). Typton fapespae sp. nov. can be distinguished from the poorly described and illustrated T. hephaestus by the presence of several (2–6) teeth on the distolateral margin of the uropodal exopod, above the terminal tooth adjacent to a stout spine [ Fig. 3 I–L; this margin has no teeth in T. hephaestus (see Holthuis 1951)]. The hammer-shaped dactylus of the major second pereiopod in T. hephaestus provides another character separating the two species. However, both features (uropodal exopod and major P2) were indirectly inferred from the description of T. vulcanus , which was described by Holthuis (1951) as "extremely close", with "the only distinct difference between the two forms [being] the shape of the posterior margin of the sixth abdominal segment". A redescription of T. hephaestus is indeed highly desirable.

The serrated distolateral margin of the uropodal exopod characteristic of T. fapespae sp. nov. is also present in T. spongicola and T. holthuisi . However, T. fapespae sp. nov. differs from these two species by the subquadrate merus of the major second pereiopod bearing a field of small but conspicuous, sharp denticles on the ventral surface ( Fig. 2 E, H); the merus is more rectangular and ventrally unarmed in T. spongicola and T. holthuisi (cf. Bruce 2009; De Grave 2010). Additional distinguishing features of T. fapespae sp. nov. are the more angular pterygostomial region (cf. Fig. 1 C and Bruce 2009: figs. 1, 2A and De Grave 2010: fig. 1A); the stouter dactylus of the major second cheliped (about 2.1 times as long as maximal depth in T. fapespae sp. nov. vs. 2.6 times in T. spongicola and 2.4 times in T. holthuisi ); and the more robust third and fourth pereiopods (e.g., with P3 merus about twice as long as wide in T. fapespae sp. nov. vs. four times in T. spongicola and almost three times in T. holthuisi ). The new species differs specifically from T. spongicola by the lower positioned paraorbital processes (cf. Fig. 1 B, C and Bruce 2009: fig. 2A); the shape of the antennal scaphocerite (cf. Fig. 2 D and Bruce, 2009: fig. 3D); and the stronger median tooth on the posterodorsal margin of the sixth abdominal somite, reaching beyond lateral teeth in T. fapespae sp. nov. vs. not reaching beyond them in T. spongicola (cf. Fig. 1 F, G and Bruce 2009: figs. 1, 3J). Typton fapespae sp. nov. differs specifically from T. holthuisi by the pollex of the minor second pereiopod ending in a simple tip (vs. with bifid tip in T. holthuisi , cf. Fig. 2 J, L and De Grave 2010: fig. 2J); the dactyli of the ambulatory pereiopods (P3–5) furnished with much smaller denticles on the corpus and with an unarmed unguis (vs. with much larger denticles on the corpus and some denticles also on the unguis in T. holthuisi , cf. Fig. 3 D, E and De Grave 2010: fig. 3D, F); the shorter dorsolateral spines of the telson (about 0.10 telson length in T. fapespae sp. nov. vs. 0.14 in T. holthuisi , cf. Fig. 1 H and De Grave 2010: fig. 1I); and the presence (in most specimens) of a minute median tooth on the posterior margin of the telson (absent in T. holthuisi , cf. Fig. 1 J and De Grave 2010: fig. 1J). Regarding its size, T. fapespae sp. nov. (pocl 1.9–3.4 mm) is intermediate between the somewhat smaller T. holthuisi (pocl 1.4–1.5 mm, De Grave 2010) and much larger T. spongicola (pocl of ovigerous females 6.5–7.5 mm, Bruce 2009).

Typton fapespae sp. nov. can be easily distinguished from all other western Atlantic species of Typton , including all species previously reported from Brazilian waters ( T. carneus , T. distinctus , T. gnathophylloides , T. prionurus , T. tortugae ), by the presence of a strong median tooth on the posterodorsal margin of the sixth abdominal somite.

Figures

FIGURE 1. Typton fapespae sp. nov., male paratype [CCDB 4486] (A, B, D – J) and female paratype [CCDB 3413] (C) from Ubatuba, São Paulo, Brazil: A, frontal region and cephalic appendages, dorsal view; B, frontal region, lateral view; C, frontal region and proximal part of cephalic appendages, lateral view; D, posterior margin of carapace, lateral view; E, abdomen, lateral view; F, sixth abdominal somite, dorsal view; G, same, lateral view; H, telson, dorsal view; I, same, posterior margin, dorsal view; J, same, spines and setae ommited, dorsal view. Scale bars: A – E = 0.5 mm, F – H = 0.25 mm, I, J = 0.1 mm.

FIGURE 2. Typton fapespae sp. nov., female paratype [CCDB 3413] (A, B, E, K – N) and male paratype [CCDB 4486] (C, D, F – J) from Ubatuba, São Paulo, Brazil: A, antennule and antenna, ventral view; B, same, proximal articles, ventral view; C, antenna, proximal portion, ventromesial view; D, same, scaphocerite, dorsal view; E, third maxilliped, lateral view; F, first pereiopod, lateral view; G, major second pereiopod, lateral view; H, same, mesial view; I, same, merus, lateral view; J, same, distal portion of chela, mesial view; K, minor second pereiopod, lateral view; L, same, carpus and chela, mesial view; M, same, fingers, mesial view; N, same, lateral view. Scale bars: A, F, J, K, L = 0.5 mm; B, C, E, I, M, N = 0.25 mm; D = 0.1 mm; G, H = 1 mm.

FIGURE 3. Typton fapespae sp. nov., male paratype [CCDB 4486] (A – J) and female paratype [CCDB 3413] (K, L) from Ubatuba, São Paulo, Brazil: A, third pereiopod, lateral view; B, fourth pereiopod, lateral view; C, fifth pereiopod, lateral view; D, third pereiopod, dactylus and propodus, mesial view; E, fourth pereiopod, dactylus and propodus, lateral view; F, fifth pereiopod, dactylus and propodus, lateral view; G, first pleopod, ventral view; H, second pleopod, ventral view; I, left uropodal exopod (male), distolateral angle, dorsal view; J, right uropodal exopod (male), distolateral angle, dorsal view; K, left uropodal exopod (female), distolateral angle, dorsal view; L, right uropodal exopod (female), distolateral angle, dorsal view. Scale bars: A – C = 0.5 mm, D – H = 0.25 mm, I – L = 0.1 mm.

FIGURE 4. Typton fapespae sp. nov., male holotype [MZUSP 31127] from São Sebastião, São Paulo, Brazil: A, habitus in life, dorsal view; B, same, lateral view. Photographs: A. Anker.

FIGURE 5. Typton fapespae sp. nov., male paratype [MZUSP 31128] and ovigerous female paratype [MZUSP 31130] from São Sebastião, São Paulo, Brazil: A, habitus in life (male), lateral view; B, habitus in life (female), lateral view. Photographs: A. Anker.