Hi Rando,

This seaweed looks like Ahnfeltiopsis concinna. 

Ahnfeltiopsis concinna (J. Agardh) Silva & DeCew

http://www.botany.hawaii.edu/ReefAlgae/What%20plants%20look%20like/Plants%20Ahnfeltiopsis%20concinna.htm

let me know if i am incorrect

2nd picture from top: the bushy one looks like Gracillaria & the brown long leaf type looks like Spathglossum. 

Hi Rando!

According to the 1st picture, that red algae could be Ahnfeltiopsis concinna as Priyanka mentioned; however, plants of Ahnfeltiopsis durvillei can also match with its characteristics. In my opinion, A. durvillei is more probable because this species is one of the most abundant intertidal species at middle levels along the exposed, rocky coast of Peru (Dawson et al. 1964).

In the second picture, it seems that the thalli of that algae are flattened at some point. In this case, Asterfilopsis furcellata could be the species.

In the third picture, the yellowish algae could belong to Ahnfeltiopsis and red to dark-brown ones could be Ahnfeltiopsis or Asterfilopsis furcellata. The difference in colors is due to possition in the intertidal (yellowish if it s more exposed to the light or dessication). Also, the small blades attached to the rock could be Pyropia/Porphyra, however it is necessary a better picture to confirm that.

Does the last two pictures belong to the first one? If this is the case, the abscence of hypha-like filaments in the medulla could support the idea of Priyanka; however these filaments are also not present in A. durvillei.

As a recommendation, for red algae belonging to Phyllophoraceae (as Asterfilopsis and Ahnfeltiopsis) reproductive structures are necessary for correct iddentification.

Best luck!

Btw, Pisco is a really good place! I have some collections from there

1st pict.  may be Ahnfeltiopsis  as mentioned by  Priyanka and Jose, 2nd pic  is the combination many algal forms such as Ulva, Porphyra, Laminaria including Ahnfeltiopsis. Here and there some patches of Cladophora also visible (may be)

3rd pic also combination of few algal forms including Ahnfeltiopsis.

It is better to isolate the material and take the photographs separately for proper identification, otherwise it is difficult to identify the material. 

are  last two pics TS of thallus of the above algae?

Hello, thank you for the responses. I was actually trying to identify only the one species (probably Ahnfeltiopsis sp) shown in the all 5 pictures. The last two images show the cross-section of the thallus shown in the first picture.

Rando, i think A. durvillei is more probable as i mentioned in my previous answer. I didn't see to much A. concinna near to Pisco. However, to confirm the identification,, reproductive structures are necessary.