Chlorotocellidae, Komai, Tomoyuki, Chan, Tin-Yam & Grave, Sammy De, 2019

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 : 392-394

publication ID	https://dx.doi.org/10.3897/zse.95.35999
publication LSID	lsid:zoobank.org:pub:86895CA3-596A-4015-8350-82EEF10F9885
persistent identifier	https://treatment.plazi.org/id/CBE45390-043A-46E8-9743-7F5B167255AD
taxon LSID	lsid:zoobank.org:act:CBE45390-043A-46E8-9743-7F5B167255AD
treatment provided by	Zoosystematics and Evolution by Pensoft
scientific name	Chlorotocellidae
status	fam. nov.

Treatment

Chlorotocellidae View in CoL fam. nov.

Type genus.

Chlorotocella Balss, 1914, by present designation.

Composition.

Chlorotocella Balss, 1914 (two species), Chlorocurtis Kemp, 1925 (monotypic), Anachlorocurtis Hayashi, 1975 (three species) and Miropandalus Bruce, 1983 (monotypic).

Diagnosis.

Rostrum, if present, without teeth or fringe of setae on ventral margin ( Figs 1A View Figure 1 , 4A View Figure 4 ). Thoracic sternites without conspicuous ornamentation, such as prominences, teeth or protuberances ( Fig. 3B View Figure 3 ). Pleomere 6 posterolateral process rounded or truncate ( Figs 1C View Figure 1 , 4B View Figure 4 ). Telson with dorsolateral spiniform setae located adjacent to lateral margins ( Figs 1D View Figure 1 , 4C View Figure 4 ). Eyestalks subcylindrical, cornea distinctly shorter than eyestalk ( Figs 1E View Figure 1 , 4D View Figure 4 ). Antennular stylocerite devoid of proximolateral projection, distally obliquely truncate, bi- or tridentate ( Figs 1A, F View Figure 1 , 4E View Figure 4 ); outer flagellum with distal portion (distal to aesthetasc-bearing portion) reduced, consisting only of few articles ( Figs 1A View Figure 1 , 4E View Figure 4 ). Maxilliped 2 without podobranch ( Figs 1L View Figure 1 ). Maxilliped 3 with no exopod ( Figs 2A View Figure 2 , 5A View Figure 5 ). Pereopod 1 fingers absent ( Figs 2B View Figure 2 , 5B, C View Figure 5 ). Pereopod 2 always subequal; basis without small process on lateral surface of basis; carpus consistently divided into three articles ( Figs 2C View Figure 2 , 5D View Figure 5 , 6D View Figure 6 ). Arthrobranchs always absent from maxilliped 3 and pereopods.

Remarks.

Characters differentiating Chlorotocellidae fam. nov. and Pandalidae are summarized in Table 1, with the character states of Chlorotocellidae fam. nov. being synapomorphic against Pandalidae (see Liao et al. 2019). Supplementary figures of diagnostic characters can be found in Hayashi (1975: figs 1-3), Bruce (1983: figs 1-5), Hayashi (2007a: figs 538, 539, 542 a–f), Hayashi (2007c: figs 557 –559a–e), Horká et al. (2014: figs 1-8), and Ahyong (2015: figs 9, 10).

Amongst these characters, the division of the carpus of pereopod 2 and quite possibly the absence of ventral rostral teeth can readily be used to differentiate the two families, although determination of their polarity is not straightforward. In Chlorotocellidae the pereopod 2 car pus is consistently divided into three articles, whereas in Pandalidae , the number of the carpal articles is quite variable according to taxa, but none are tri-articulate (cf. Komai 1994). The absence of ventral rostral teeth is also reported in three taxa of the pandalid genus Plesionika ( Chace 1985) but with doubt (see Chace 1985; Komai et al. 2005; Hayashi 2009; Komai 2011; Li and Chan 2013). Such a similarity, if really present, can be resulted from homoplasy ( Liao et al. 2019).

According to the Ancestral State Reconstruction (ASR) analysis by Liao et al. (2019), Pandalidae is characterized by the following synapomorphic features: (1) second article of the antennular peduncle with a few minute spiniform setae on the dorsodistal margin ( Fig. 6A View Figure 6 ); (2) mandibular palp consisting of three articles ( Fig. 6B View Figure 6 ); and (3) basis of pereopod 2 bearing a small process on the lateral surface ( Fig. 6C View Figure 6 ). In these regards, Chlorotocellidae shows the following plesiomorphic states: (1) mandibular palp tends to be reduced, being absent or consisting of two articles at most ( Figs 1H View Figure 1 , 4H View Figure 4 ); (2) second article of the antennular peduncle is unarmed on the dorsodistal margin ( Figs 1A, F View Figure 1 , 4E View Figure 4 ); and (3) basis of pereopod 2 being unarmed ( Fig. 6D View Figure 6 ).

Nevertheless, an assessment of the polarity of the development of the mandibular palp is fraught with difficulty and heavily dependent on outgroup selection. In Caridea in general, however, a reduction of the mandibular palp is considered to be derived (e.g., Christoffersen 1987, 1989), as compared to the well-developed palp in Dendrobranchiata and most other Decapoda .

Furthermore, the other two characters are subject to reversal within Pandalidae ( Komai 1994; Liao et al. 2019). In species of Thalassocaris and Chlorotocoides (previously in their own family Thalassocarididae , but now considered part of Pandalidae ), the second article of the antennular peduncle is devoid of spiniform setae and the basis of the second pereopods unarmed ( Komai 1994).

In addition to the three aforementioned characters, the possession of a rounded laminar expansion at the inner distal angle of the first article of the mandibular palp ( Fig. 6B View Figure 6 , inset) might be synapomorphic to Pandalidae ( Komai 1994; Liao et al. 2019), although a secondary loss of this structure is observed in Thalassocaris and Chlorotocoides ( Komai 1994; Liao et al. 2019). It is impossible to evaluate the homology of this character for the taxa assigned to Chlorotocellidae , because in those taxa, the mandibular palp only comprises two articles ( Chlorotocella ) or is absent ( Chlorocurtis , Anachlorocurtis and Miropandalus ), and the homology of the articles has not been established in taxa with different numbers.