Petrarca goanna Grygier, 1991: 35–38

Kolbasov, Gregory A., Savchenko, Alexandra S., Yu, Meng-Chen, Tsao, Yao-Feng, Ganmanee, Monthon & Chan, Benny K. K., 2023, Integrative taxonomy, larval biology and functional morphology of the little known gall-forming coral endoparasite Petrarca (Thecostraca: Ascothoracida), Zoological Journal of the Linnean Society 198, pp. 767-801 : 771-774

publication ID	https://doi.org/ 10.1093/zoolinnean/zlad009
publication LSID	lsid:zoobank.org:pub:A2863AB5-855B-4549-89EC-A57C46140CD9
DOI	https://doi.org/10.5281/zenodo.8142204
persistent identifier	https://treatment.plazi.org/id/03FA8E1E-AB44-FF81-453E-FEDBFDA3FE20
treatment provided by	Plazi
scientific name	Petrarca goanna Grygier, 1991: 35–38
status

Treatment

Petrarca goanna Grygier, 1991: 35–38 , figs 18, 19.

Material examined: Four specimens in Astreopora sp. , two specimens in Turbinaria mesenterina ( Lamarck, 1816) and 12 specimens in Turbinaria sp. , 22°40 ʹ 39.2 ″ N, 121°28 ʹ 57.2 ″ E, Green Island (L ǜ d ǎ o), Taiwan, 24.04.2015, at 4–20 m depth. Fifteen specimens in Turbinaria frondens ( Dana, 1846) and four specimens in Turbinaria sp. , 10°41 ʹ 56.5˝N, 99°24 ʹ 28.4 ″ E, Koh Khai Island, Chumphon, Thailand, 06– 07.07.2019, at 3–4 m depth.

Grygier (1991a) provided a detailed description of this species. We provide additional observations obtained mainly with SEM.

Diagnosis: Carapace valves of adults with crenulated margins formed by protruding outer ends of five to eight radially directed dorsal and posterior irregular ridges; ridge exterior with irregular lumpy inflations; ventral side of carapace with few papillae; lateral surface of carapace without small papillae. Labrum with short lateral extensions; maxillae mostly exposed; mandibles with 15–25 sharp, simple or bifid teeth; teeth of the maxillules in lower half with spiniform tips and tending to form two rows; six pairs of thoracopods, first thoracopod setiform; penis with relatively small, squarish rami.

Description: Living specimens pink or crimson-coloured ( Fig. 1F View Figure 1 ); tip of penis often extending out of carapace ( Fig. 2C, E, F View Figure 2 ). Adult (mature) specimens 5.26–6.08 mm long, 4.32–6.15 mm high ( Figs 2A–D View Figure 2 , 5A View Figure 5 ); young (juvenile) specimens ( Fig. 2E–G View Figure 2 ) 2.80–3.83 mm long and 2.40–3.33 mm high. Carapace ( Figs 2 View Figure 2 , 5A View Figure 5 ) roughly ovoid (spherical), valves with short anteriodorsal hinge line, lateral surfaces with five to eight radial ridges with irregular lumpy inflations. These inflations are less developed in the anterior part of adults and in young specimens. Dorsal and posterior margins of valve crenulated due to carapace ridges ( Figs 2 View Figure 2 , 5F View Figure 5 ). Ventral margin with few inconspicuous papillae ( Fig. 5C, D View Figure 5 ) with central micropore on tip ( Fig. 5E View Figure 5 ).Cuticle on lateral, external and internal surfaces of carapace with dense, polygonal, small swellings or bumps but without papillae, teeth or ctenes ( Fig. 5B, G View Figure 5 ).

Body inflated, crescent-like, enclosed between carapace valves ( Fig. 5F View Figure 5 ). Cephalon with large adductor muscle lying above big oral cone ( Fig. 5F View Figure 5 ) flanked by five-segmented antennules. Thorax with arched dorsal margin but without distinct segmentation, with clusters of rudimentary uniramous thoracopods; cuticle of thorax with ctenoid scales in dorsal part ( Fig. 5H View Figure 5 ). Abdomen with massive first segment bearing long penis and vestigial rear part ( Figs 5F View Figure 5 , 7D View Figure 7 ).

Antennules somewhat prehensile, with little armament or external sculpture on two distal segments ( Figs 3A–D View Figure 3 , 6A–D View Figure 6 ). First segment irregularly rectangular, narrowing somewhat distally; second segment trapezoidal; third segment almost triangular, narrowing toward lower/ ventral margin; fourth segment slightly longer than wide, with slightly curved ventral margin, short distal seta inserted at anteriodorsal corner ( Figs 3A, D View Figure 3 , 6A, B View Figure 6 ). Fifth segment rectangular, slightly shorter and narrower than fourth and armed with sensory and grasping structures ( Figs 3A–C View Figure 3 , 6A, C, D View Figure 6 ). Short but massive curved claw with smooth concave margin arising from distal end of segment. Three rudimentary setae at base of claw and to each side; tiny pores (three to four) on inner and outer lateral sides. Claw sheathed by large, oval claw guard on posteriodistal corner; claw guard with three vestigial, distal setae with a terminal pore; developed aesthetasc almost half as long as claw guard, inserted closer to its distal end and terminating with four outgrowths, rudimentary seta at base of aesthetasc ( Fig. 6A, D View Figure 6 ). Ventral (postaxial) margin of fifth segment and claw guard with wrinkled cuticle bearing tiny pores ( Fig. 6C View Figure 6 ).

Oral cone prominent, consisting of massive labrum underlaid posteriorly with massive, fused maxillae, unpaired medial languette and paired mandibles and maxillules ( Figs 3E–J View Figure 3 , 5F View Figure 5 , 6E–H View Figure 6 ). Labrum prow-shaped, with short posteriolateral extensions leaving maxillae largely exposed, exterior with dense ctenoid scales ( Figs 3E View Figure 3 , 6E View Figure 6 ). Medial languette with groups of sharp denticles (two to five) along anterior margin and dense basal pores forming ‘pore-field’ ( Fig. 6F View Figure 6 ). Mandibles ( Figs 3F, G View Figure 3 , 6G View Figure 6 ) elongated, outer/upper margin with hillock and clusters of dense, thin setae in middle part, cutting edge straight, with 15–21 sharp, simple or rarely bifid teeth and one to two small spinules in middle part. Maxillules ( Figs 3H, I View Figure 3 , 6H View Figure 6 ) with sclerotized, triangular distal parts, inner margin with 17–20 teeth, teeth in upper half with often blunt tips, while those in lower half smaller, irregular, with spiniform tips and tending to form two irregular rows. Fused maxillae ( Fig. 3J View Figure 3 ) ending in a pair of short, rounded lobes, with dense ctenoid scales on lateral surfaces ( Fig. 7B View Figure 7 ), distal ends covered with sclerotized, thick and wrinkled cuticle without denticles, pores or setules ( Fig. 7A View Figure 7 ).

Thoracopods 2–6 ( Figs 4B View Figure 4 , 5F View Figure 5 ) are present in all examined specimens, uniramous, unsegmented, grouped in cluster and arranged in an unorderly sequence in lateral view. Thoracopods 2–4 are conical with wide bases, while thoracopods 5 and 6 are shorter and narrower. Cuticle of thoracopods 2–6 has dense and long ctenoid scales ( Fig. 7C View Figure 7 ). Batteries of numerous ampuliform seminal receptacles ( Fig. 4B View Figure 4 ) associated with thoracopods 2–5 (~7, 20, 20 and 11 receptacles, respectively). Setiform thoracopod 1 ( Fig. 4A View Figure 4 ) present in all studied specimens.

Long, thick, terminally bifid penis originates from large first abdominal segment ( Figs 4D View Figure 4 , 5F View Figure 5 , 7E View Figure 7 ). Long shaft of penis supports two small, squarish rami about 190–200 µm long ( Figs 4D View Figure 4 , 7E View Figure 7 ). Distal half of penis, including rami, bearing numerous short but wide conical setae. Rest of abdomen vestigial, apparently consisting of two segments ( Figs 4C View Figure 4 , 5F View Figure 5 , 7D View Figure 7 ). Posterior end of abdomen with cleavage that may represent rudimentary furcal rami ( Fig. 7D View Figure 7 ).

Remarks: The morphology of our specimens generally corresponds to that of the individuals described by Grygier (1991a), but differs in having rare ventral papillae on the carapace (absent in Grygier’s specimens) and presence of all six pairs of thoracopods (inconsistent number of thoracopods in Grygier’s material). However, these details could have been overlooked in the type material. This is the first finding of Petrarca in scleractinian corals of the genus Astreopora .