Perinereis heterodonta Gravier, 1899

Yousefi, Shetav, Rahimian, Hasan, Nabavi, Seid Mohammad Bagher & Glasby, Christopher, 2011, Nereididae (Annelida: Polychaeta) from intertidal habitats in the Gulf of Oman, Iran, Zootaxa 3013, pp. 48-64 : 54-59

Perinereis heterodonta Gravier, 1899

( Figs 2 B, 5A–F)

Perinereis heterodonta Gravier, 1899a: 242 , fig 16–19; Fauvel, 1953: 214, fig. 109e.

Material examined. Iran, Gulf of Oman, Chabahar, Shahid beheshti wharf, 4 specimens ( ZUTC Ann. 1124), 2 specimens ( NTM W23739); Chabahar, Portuguese Castle, 6 specimens ( ZUTC Ann.1127), 1 specimen ( NTM W23738); Djod, 5 specimens ( ZUTC Ann. 1136); Jask, 5 specimens ( ZUTC Ann.1138); Sirik, 4 specimens ( ZUTC Ann. 1139).

Description. Material examined 40–160 mm long, 90–198 chaetigers, 1–4 mm wide at chaetiger 10 (excluding parapodia). Colour in alcohol is light cream, no other pigment ( Fig. 2 B). Longest tentacular cirri extending back 1– 6 chaetigers ( Fig. 5 B), jaw length 1–4 mm. Paragnaths on maxillary ring arranged as follows: I = 1–2, II = 5–12, III = 8–14, IV = 12–26. Paragnaths on oral ring arranged as follows: V = 0–1, VI = 14–24 transverse bars, VII–VIII = 20–35 conical paragnaths arranged in three irregular rows ( Fig. 5 A). Anterior notopodia have two long ligules of equal size, dorsal cirrus is equal to dorsal ligule ( Fig. 5 C). Anterior neuropodia have two ligules of equal size, ventral ligule is equal to ventral cirrus ( Fig. 5 C). Posterior parapodia with notopodial ligules triangular, neuropodial ligules similar in shape to anterior ones, dorsal and ventral cirri relatively shorter than anterior ones ( Fig. 5 D). Notochaetae all homogomph spinigers. Neurochaetae are homogomph spinigers, heterogomph falcigers and heterogomph spinigers (posterior body only) ( Fig. 5 E, F).

Remarks. The present specimens fit the original description of P. heterodonta by Gravier (1899a) in all key characters ( Table 3 ). Fauvel (1953) also described Perinereis heterodonta , although he considered it to be a variety of P. nuntia . Perinereis heterodonta was considered a synonym of P. nuntia by Wilson & Glasby (1993) and Wehe & Fiege (2002). However, examination of many Perinereis specimens in this study enabled us to distinguish the two species. Perinereis heterodonta differs from P. nuntia in having shorter tentacular and dorsal cirri, 0–1 paragnaths in Area V and in lacking heterogomph spinigers in anterior neuropodia ( Table 3 ). Further, P. heterodonta appears to have more paragnaths in Area VI (although there is overlap in values between the two species) and fewer paragnaths in Areas VII–VIII (no overlap). Perinereis heterodonta is therefore raised from synonymy and herein treated as a valid species.

Regional distribution and habitat. Rocky, sandy and coral shores, and under stones on sandy shores of Gulf of Oman (Chabahar, Chabahar, Djod, Jask). Also Persian Gulf ( Table 2 ).

World distribution. Djibouti (type locality); Madagascar.

Perinereis horsti Gravier, 1899b: 288 , figs 1, 2.

Material examined. Iran, Gulf of Oman, Jask, 10 specimens ( ZUTC Ann. 1105), Sirik, 7 specimens ( ZUTC Ann. 1140), 1 specimen ( NTM W23742).

Description. Body 3–4 cm long, 93–102 chaetigers, 2–3 mm wide at chaetiger 10 (excluding parapodia). Colour in alcohol is cream with additional light brown pigment on dorsal surface of prostomium and peristomium ( Fig. 2 C). Longest tentacular cirri extending back 2–5 chaetigers. Paragnaths on maxillary ring arranged as follows: I = 1–2, II = 10–20, III = 14–24, IV = 15–24. Paragnaths on oral ring arranged as: V = 3 conical paragnaths, VI = 2 transverse bars, VII–VIII = 22–30 in two or three conical rows ( Fig. 6 A, B). Anterior and posterior parapodia with slender notopodial ligules of similar size. Dorsal cirri equal in length to dorsal notopodial ligule ( Fig. 6 C, D). Notochaetae all homogomph spinigers. Neurochaetae are homogomph and heterogomph spinigers and heterogomph falcigers ( Fig. 6 E).

Remarks. Perinereis horsti (type locality Djibouti) was considered a synonym of P. vancaurica (Ehlers) (type locality Vancauri, Luzon, Philippines) by Hutchings et al. (1991) and Wehe & Fiege (2002). However, the two species can be distinguished on the basis of paragnath counts. The material in the present study is similar to the original description of this species by Gravier, except for the slightly lower paragnath numbers. According to Gravier, the paragnaths are arranged as follows: I = 1, II = 2–6, III = 13 in three rows, IV = 10–12, V = 4, VI = 2 transverse bars, VII–VIII = two rows of paragnaths, one having 8 paragnaths and the other having 14. The type and shape of chaetea in the present material also fits the description of this species by Gravier. Perinereis horsti may be distinguished from P. vancaurica as re-described by Hutchings et al. (1991) by having fewer paragnaths in areas VII– VIII (22–30 compared 58–129) and fewer paragnaths in area IV (15–24 compared to 40–88). The description of Hutchings et al. (1991) included topotype material of P. vancaurica from the Philippines as well as Australian specimens; it is not representative of P. horsti , which is herein raised from synonymy and treated as a valid species.

Regional distribution and habitat. Rocky, sandy, muddy, coral shores of Gulf of Oman (Jask). Also Persian Gulf, Arabian Sea ( Table 2 ).

World distribution. Djibouti, Gulf of Aden (type locality).

Figures

FIGURE 2. Dorsal views of anterior end of selected nereidid species collected from the intertidal of Gulf of Oman, A, Nereis coutieri, body width about 1 mm; B, Perinereis heterodonta, body width about 2.5 mm; C, Perinereis horsti, pharynx everted, body width about 2 mm; D, Perinereis nuntia, pharynx everted, body width about 3 mm; E, Pseudonereis trimaculata, pharynx everted; body width about 2 mm.

FIGURE 5. Perinereis heterodonta, A, anterior end, ventral view, dissected pharynx; B, anterior end, dorsal view; C, anterior parapodium; D, posterior parapodium; E, neuropodial heterogomph falciger, anterior parapodium; F, neuropodial homogomph spiniger, posterior parapodium.

FIGURE 6. Perinereis horsti, A, anterior end, dorsal view showing everted proboscis; B, ventral view of same; C, anterior parapodium; D, posterior parapodium; E, neuropodial heterogomph falciger, anterior parapodium.

Tables

TABLE 3. Differential comparision of selected characters between Perinereis heterodonta and P. nuntia. Information for the types obtained from figures and description of Gravier (1899 a) and Savigny (1818, 1822). DNL = dorsal notopodial lobe.? information not available or not considered reliable.

	P. heterodonta type (n=1)	P. heterodonta Gulf of Oman (n=23)	P. nuntia type (n=1)	P. nuntia Gulf of Oman (n=17)
Area V paragnaths: number	0	0–1	3	3
Area VI paragnaths: number	10–16	14–24	10–12	13–20
Areas VII–VIII paragnaths: number	18	20–35	41	36–58
Longest tentacular cirri: extends to chaetiger	~5	1–6	?	8–14
Heterogomph spinigers in anterior neuropodia: p/a	absent	absent	present	present
Dorsal cirri posteriorly: length relative to DNL	?	0.6–1.0	4–5	1.5–3.0
Perinereis horsti Gravier, 1899 (Figs 2C, 6A–E)