Chlorotocella Balss, 1914

Komai, Tomoyuki, Chan, Tin-Yam & Grave, Sammy De, 2019, Establishment of a new shrimp family Chlorotocellidae for four genera previously assigned to Pandalidae (Decapoda, Caridea, Pandaloidea), Zoosystematics and Evolution 95 (2), pp. 391-402 : 395-396

Genus Chlorotocella Balss, 1914

Chlorotocella Balss 1914: 33; Holthuis 1955: 118, 127; 1993: 263, 266; Hayashi 2007a: 150.

Type species.

Chlorotocella gracilis Balss, 1914.

Diagnosis.

Rostrum elongate, very slender, gently upturned, exceeding far beyond distal margin of antennal scaphocerite, dorsally armed with two teeth around rostral base (one postrostral); ventral margin unarmed ( Fig. 1A ). Carapace without projections on dorsal midline; supraorbital tooth present; suborbital lobe prominent, longer than antennal tooth, distally rounded, slightly constricted at base; pterygostomial tooth moderately small ( Fig. 1A, B ). Pleomeres 1-6 dorsally rounded; pleomeres 4 and 5 each with pair of posterolateral teeth; p leomere 5 with deep transverse groove near posterodorsal margin; pleuron with small posteroventral tooth ( Fig. 1C ). Pleomere 6 with minute posteromedian tooth; posteroventral angle with minute tooth ( Fig. 1C ). Telson with additional anterior pair of spiniform setae located more mesial to other lateral series of spiniform setae; posterior margin narrow, slightly produced medially, with two pairs of unequal spiniform setae ( Fig. 1D ). Eye with ocellar spot (nebenauge) ( Fig. 1E ). Antennular peduncle article 1 armed with tooth on dorsodistal margin ( Fig. 1A, F ). Mandible with two-articulated palp ( Fig. 1H ). Maxillule palp without distal outer lobule ( Fig. 1I ). Maxilla with short, moderately slender endopod ( Fig. 1J ). Maxilliped 1 with coxal and basial endites well developed, both with row of setae on mesial margin; exopodal flagellum well developed ( Fig. 1K ). Maxilliped 2 endopod with dactylus located at distal portion of propodus; exopod well developed ( Fig. 1L ). Pereopod 1 fingers completely reduced ( Fig. 2B ). Pereopods 3-5 propodi each with closely spaced, short to long spiniform setae in distal 0.2; carpi each with few spiniform setae on lateral surface; meri usually with spiniform setae arranged in two rows; ischia each with spiniform seta on ventral surface in pereopods 3 and 4 ( Fig. 2 D–F ). Male pleopod 1 endopod without appendix interna ( Fig. 1M ).

Composition.

Chlorotocella gracilis ; C. spinicaudus (H. Milne Edwards, 1837).

Distribution.

Indo-West Pacific, South Australia; shallow subtidal to 60 m; free living in algal-rich habitats or facultatively associated with gorgonarians and hydroids.

Remarks.

At present, two species are assigned to Chlorotocella ( De Grave and Fransen 2011), viz., C. gracilis (type species) and C. spinicaudus . Holthuis (1995) clarified that Hippolyte spinicaudus H. Milne Edwards, 1837 was a senior subjective synonym of Pandalus leptorhynchus Stimpson, 1860. In addition, a third taxon, which was placed in the synonymy of C. spinicaudus by De Grave and Fransen (2011), Pandalus (Parapandalus) leptorhynchus var. gibber Hale, 1924, was described from Gulf St Vincent, South Australia, characterized mainly by the prominently crested tergite of pleomere 3 (see Hale 1927). This taxon has been seldom mentioned in more recent literature. Ledoyer (1984) illustrated a specimen with a weakly crested tergite from Nouméa (New Caledonia), which he assigned to C. gracilis , but left it open as to whether this should be a distinct species or merely a "forme gibber " of C. gracilis . In contrast, Poore (2004) treated the taxon as a distinct species, C. gibber (Hale), noting it was restricted to the Gulf St Vincent (South Australia).

Because no modern descriptions are available for C. spinicaudus , the above generic diagnosis is largely based on C. gracilis and the summary information available on the other species. It seems possible that Hale’s (1924) taxon might be distinct from C. gracilis and C. spinicaudus as it is characteristic by having a highly crested tergite of the pleomere 3 ( Hale 1924: pl. 4, fig. 6; 1927: fig. 35). Reassessment of the taxonomic status of C. spinicaudus and Pandalus (Parapandalus) leptorhynchus var. gibber will be necessary to fully clarify the taxonomy of the genus.

Figures

Figure 1. Chlorotocella gracilis Balss, 1914, male (cl 5.0 mm), CBM-ZC 12534. A. Carapace, antennule and antenna, lateral view (left eye removed); B. Anterior part of carapace, lateral view; C. Pleon, lateral view; D. Telson, dorsal view; E. Left eye, dorsal view; F. Left antennular peduncle, dorsal view; G. Left antenna, ventral view; H. Left mandible, outer view; inset, palp, outer view; I. Left maxillule, outer view (coxal endite missing); J. Left maxilla, outer view; K. Left maxilliped 1, outer view; L. Left maxilliped 2, outer view; M. Endopod of left pleopod 1, ventral view.

Figure 2. Chlorotocella gracilis Balss, 1914, male (cl 5.0 mm), CBM-ZC 12534. Left thoracic appendages in lateral view. A. Maxilliped 3; B-F. Pereopods 1 - 5, respectively.