Results

Order Amphipoda Latreille, 1816

Suborder Senticaudata Lowry & Myers, 2013

Family Caprellidae Leach, 1814

Genus Caprella Lamarck, 1801

Caprella moradi Momtazi, Sari & Darvish, 2020

(Figs. 2–4)

Caprella moradi: Momtazi et al., 2020: 562–571, figs. 1–6.

Caprella danilevskii: Gaikwad & Sautya, 2022: 33–39, figs. 1–6.

Material examined. 8 males, 5.0–10.0 mm (LFSC.ZRC-289), Diu (20°42’06.8”N 70°55’01.2”E), Gujarat, India, 20 January, 2023, coll. D.R. Thacker; 2 males, 6.0 & 7.0 mm (LFSC.ZRC-289), Veraval, 9 February, 2023, Coll. D.R. Thacker.

Diagnosis. Body surface covered with four rows of small setae (Figure 3H). Male gnathopod 2 propodus anterior margin curved (Figure 4B). Gills 3 and 4 unequal in size (Figure 4C & D).

Figure 1.

Map showing the known geographical distribution of Caprella moradi (Momtazi et al., Reference Momtazi, Sari and Darvish2020), including the type locality (Momtazi et al., Reference Momtazi, Sari and Darvish2020) and records obtained in the present study.

Figure 2.

Caprella moradi (Momtazi et al., Reference Momtazi, Sari and Darvish2020), male, 7.5 mm (LFSC.ZRC-289). Scale bar = 1.0 mm.

Figure 3.

Caprella moradi (Momtazi et al., Reference Momtazi, Sari and Darvish2020), male, 8.2 mm (LFSC.ZRC-289). (A) Antenna 1; (B) Antenna 2; (C) Maxilla 1; (D) Maxilla 1; (E) Maxilliped; (F) Labrum; (G) Labium; (H) four rows of small setae (only 3 visible here from the side view); (I) abdominal appendages. Scale bars = 0.25 mm.

Figure 4.

Caprella moradi (Momtazi et al., Reference Momtazi, Sari and Darvish2020), male, 8.2 mm (LFSC.ZRC-289). (A) Gnathopod 1; (B) Gnathopod 2; (C) Gill 3; (D) Gill 4; (E) Pereopod 5; (F) Pereopod 6; (G) Pereopod 7. Scale bars = 0.25 mm.

Description. Based on male 8.2 mm.

Head. Antenna 1 slender, length ratio of peduncular articles 1–3 1:1.63:1; flagellum with 10–11 articles; 0.35× as long as peduncle (Figure 3A). Antenna 2 stout, length ratio of peduncular articles 3–5 1:1.23:0.7; flagellum uni-articulate, articles 3 and 4 with long setae (Figure 3B). Labrum notched distally, 1.12× as long as broad, small setae on distal margin (Figure 3G). Maxilla 1 outer plate with 7 apical robust setae; palp article 2 with 4 triangular projections, 5 apical robust setae and 8–10 simple facial setae (Figure 3C). Maxilla 2 inner plate apically setose, oblique setal row absent; outer plate apically setose (Figure 3D). Maxilliped inner plate with several apical plumose setae; outer plate with 1 apical and 2 marginal robust setae, several marginal simple setae and few facial setae; palp article 4 longest; with an apical nail (Figure 3E).

Pereon. Gnathopod 1 basis longer than wide, proximally wider and narrower towards distal end, anterior margin bare, posterior with several small setae; posterior margin with a single simple seta; ischium as long as broad; merus 1.25× as long as ischium; carpus subtriangular; propodus sub-pyriform, posterior margin serrated, postero-proximal corner developed; dactylus subequal to propodus, inner margin serrated (Figure 4A).

Gnathopod 2 basis slender, bare, 0.8× as long as propodus, both margins bare; merus 1.25× as long as ischium; carpus small, triangular; propodus 4.18× as long as broad, broader distally; posterior margin convex, anterior margin with a triangular process near distal end; dactylus curved, small, reaching 0.33× length of the propodus (Figure 4B).

Pereonite 3 and 4 with gills. Gill 3 suboval, 1.75× as long as gill 4. Gill 4 smaller, suboval. Both gills with small setae surrounding the margins. Pereopod 3 and 4 absent (Figure 4C & D).

Pereopod 5 well developed with six article; basis as long as broad, posterodistal corner produced; ischium small with dorsal carina; merus as long as broad; distal margin produced medially; propodus subrectangular, longer than broad, without robust seta; dactylus curved, inner margin serrated, both margins with few small setae (Figure 4E). Pereopod 6 similar to pereopod 7 but slightly longer (Figure 4F). Pereopod 7 basis longer than broad; merus longer than broad with posterodistal corner produced; dactylus curved, inner margin serrated, both margins with few small setae (Figure 4G).

Pleon. Abdomen with a pair of hooked appendages, a pair of lateral lobes, and one dorsal rounded lobe. Appendages with few setae and 2–3 rows of robust setae on the ventral side. Lateral lobes thin, longer than the medial lobe (Figure 3I).

Remarks. Specimen examined in the present study show agreement with the description and illustrations of C. moradi given by Momtazi et al (Reference Momtazi, Sari and Darvish2020). However, it exhibits certain variations from the type specimen of C. moradi in following characters: abdominal lateral lobes are longer than the dorsal lobe (Figure 3I) whereas, in specimen from Iran (Momtazi et al., Reference Momtazi, Sari and Darvish2020) have lateral lobes shorter than the dorsal (fig. 3AbV); specimen examined here have rounded dorsal lobe (Figure 3I) whereas, in the specimen from Iran (Momtazi et al., Reference Momtazi, Sari and Darvish2020) the dorsal lobe is notched (fig. 3AbV). These variations could be due to the size difference in the examined specimens, as the specimen examined here is larger in size (8.2 mm) than the Iran specimen (6.59 mm) (Momtazi et al., Reference Momtazi, Sari and Darvish2020).

Caprella moradi shows similarity with its congener C. danilevskii in characters such as: absence of grasping spine in pereonite 5–7, short dactylus of male gnathopod 2 and a pair of hooked abdominal appendages. However, C. moradi can be differentiated from C. danilevskii by the presence of four rows of small setae on body surface (versus presence of small setae but without regular placement in C. danilevskii) and curved anterior surface of male gnathopod 2 propodus (versus straight anterior surface of male gnathopod 2 propodus in C. danilevskii). Although C. danilevskii was originally described from the Black Sea (Czerniavski, Reference Czerniavski1868), it is widely distributed and a well-documented member of the genus Caprella in East Asia, where it has been extensively studied taxonomically and ecologically (Vassilenko, Reference Vassilenko1974; Arimoto, Reference Arimoto1976; Takeuchi et al., Reference Takeuchi, Kuwabara, Hirano and Yamakawa1987, Reference Takeuchi, Matsumasa and Kikuchi2003; Lee and Hong, Reference Lee and Hong2011). The species has also been reported from the Atlantic Ocean (McCain, Reference McCain1968), the Mediterranean Sea (Krapp-Schickel, Reference Krapp-Schickel and Ruffo1993) and the Indian Ocean (Mayer, Reference Mayer1890), with intraspecific morphological variation documented among populations from these regions. Caprella moradi was subsequently described from the Gulf of Oman, Iran, based on consistent morphological differences from C. danilevskii (Momtazi et al., Reference Momtazi, Sari and Darvish2020).

Gaikwad and Sautya (Reference Gaikwad and Sautya2022) earlier documented C. danilevskii from Veraval, Gujarat, India. The identification appears questionable, as the anterior margin of the gnathopod 2 propodus in C. danilevskii is straight, whereas the illustrations by Gaikwad and Sautya (Reference Gaikwad and Sautya2022) depict a curved anterior margin (Figure 2F) resembling that of C. moradi. Additionally, the dorsal lobe of the abdominal appendages is notched in the illustrations given by Gaikwad and Sautya (Reference Gaikwad and Sautya2022) (Figure 3K), which also resembles C. moradi (fig. 3AbV). These similarities suggest that the specimen documented previously from Gujarat by Gaikwad and Sautya (Reference Gaikwad and Sautya2022) may, in fact, be C. moradi.

Ecology. Caprellids are marine benthic crustaceans found inhabiting various substrates such as algae, bryozoans, sponges and hydroids (McCain, Reference McCain1968; Guerra-García, Reference Guerra-García2004; Momtazi et al., Reference Momtazi, Sari and Darvish2020) and are also the part of fouling communities (Thiel et al., Reference Thiel, Guerra-García, Lancellotti and Vásquez2003; Ros and Guerra-García, Reference Ros and Guerra-García2012). Caprellid are an important food source of many fish species (Caine, Reference Caine1987, Reference Caine1989, Reference Caine1991). These small crustaceans form an important link between the primary producers such as algae and higher trophic taxa. In the present study, specimens were found attached to algal substrates dominated by Chaetomorpha spp. and Cystoseira spp., occurring over rocky substratum where seawater temperature ranged between 26 and 28 °C and salinity was around 33–34 PSU. Caprella moradi previously was only reported from the Gulf of Oman, Iran, and now it is first time reported from Gujarat State, India, in this study. We hypothesis that the reason behind the range extension of the species from Iran to India could be due to natural or anthropogenic sources such as any floating object or vessels.

Distribution. Djod village, Gulf of Oman, Iran (Momtazi et al., Reference Momtazi, Sari and Darvish2020) Diu and Veraval, Gujarat (this study), India. In this study, this species is first time reported from India (Figure 1).